Vegetable Oil Paints

L. L. CARRICK, University of Michigan,

HE Egyptians recognized the inedicinal proper- table waxes, pitches, or the oils from wild nuts or
T ties of linseed oil but were unacquainted with its
drying properties. Ludius used oil in encaustic
seeds. The early use of raw walnut, linseed, poppy
seed, olive, or hcmpseed oils has been noted together
paints during the reign of Agustus (63 B.C.-14 A.D,). with the advent of their refined and bleached modifi-
Vitruvius, during t h e same period, prepared a var- cation. Chinese tung oil, according to D'Incarville,
nish from Punic wax and a little oil. Dioseorides 1735, was first a common adulterant of Chinese lac-
(69-30 B.C.) recognized the dispersion properties of quers and did not commercially replace linseed oil in
oils for natural resins. Pliny the author (A.D. 23-70) many varnishes in the United States until 1900.
makes no mention of the use of oil by artists or Enamels were unknown before the beginning of the
painters. Lucanus (A.D. 37-68) mentioned the use present century. Prior to this time it was common
of oil to improve the working characteristics of color practice to apply a flat oil paint of the desired color
for paints. Galen (A.D. 131-200) coagulated drying and follow it with a coat of clear varnish to obtain
oils, such as hempseed, nut, and linseed oils by means the needed gloss. About this time it was found that
of litharge, white lead, and umber. Actius (A.D. pigments could be ground into a varnish vehicle a~d
540) emphasized to the arts the drying properties give a product which was stable in the container.
and varnish potentialities of linseed, castor, and nut This product would give in one operation a film of
oil used by Gilders and encaustic painters. Lucca the desired color which had high gloss and good
(A.D. 800) was the first to record instructions for levelling.
preparing varnish from resin and boiling linseed oil. The commercial use of perilla, fish, soybean, oiti-
In the 11th century Theophilis, a monk, gave explicit eiea, sunflower, safflower, and dehydrated castor oil
instructions for melting resin until clear, adding hot in paints are attributed to developments in the 20th
linseed, olive, walnut, or poppyseed oils and continu- century.
ing to heat the mixture until a drop remained clear Such paints or metal primers, sanding undercoats,
upon cooling. He complained about the slow drying baking colored enamels, and oil stains are among re-
characteristics of the fihn and resorted to exposure cent developments required by the industrial ad-
to the sun to accelerate drying. In principle this is vances of a mechanical age and the tremendous
the same method employed at the present time in increased demand as a result of shortened production
many varnish cooks. schedules, production lines, and increased market
Eraelius and Petrus (12th to 13th centuries pressure.
A.D.) recorded methods for the extraction and re-
fining of oil by adding small quantities of lime, fol- Although modern scientific studies have uncovered
lowed by heating and continued skinning. Petrus and developed many substitutes and partial replace-
also used white lead as a drier and bleached oils in ments for drying oils, it has not been able to decrease
the sun with frequent agitation. The protective value their importance to any appreciable extent. Today's
of drying oils was generally accepted in France, paint and varnish industry and many synthetic resin
England, and Germany in the 13th and 14th cen- industries would be greatly handicapped if forced to
turies. Jacobus de Tholeto, 1450, was among the first formulate the variety of modern organic protective
to suggest that metallic salts be cooked with the resin coatings industrially, without the aid of the oil prod-
and oil to hasten the subsequent drying rate. No men- ucts of nature.
tion of thinning varnish was made until 1736, when There are a large number of factors which have
Alberti of Magdeburg thinned varnish with turpen- g r e a t influence upon the utility of organic protective
tine, which remained the principal thinner of varnish coating oils, any one of which may spell the difference
until 1880 after which petroleum distillate was com- between usability or be completely or largely respons-
mercially employed. Watin, 1773, realized the com- ible for the oil's unusability. These factors may be
mercial possibilities of varnish and published a book roughly grouped into two categories, technical factors
in which he offered varnish for sale to other crafts- and economic factors.
men so that they would not have to cook their own The economic factors, in turn, are dependent upon
varnish. In the 13th and 14th centuries the records such subfactors as steady availability of the oil, sta-
show that Liibeck, Kolmar, van Eyek, Cennini, A1- bility of the oil supply, physical and chemical stabil-
eherius, and other artists and craftsmen demonstrated ity of the oil, low price of the oil, and stability of the
the value of common oils, such as raw and refined price. The technical factors may be further divided
walnut, linseed, hempseed and poppy seed, for use as into the properties of the liquid oil and the properties
vehicles in portrait and decorative paints. At Canter- of the drying or dried oil film. A few of the liquid
bury (13th century) and Ely (14th century) the oil properties which must be evaluated in terms of
records disclose that oil was used in decorative paints. the formulation requirements are acidity; color~
Oil was first used commercially in the manufacture odor ; viscosity ; ~amount of saturated f a t t y acids;
of varnish in England in 1790, France 1820, New amount of unsaturated fatty acids; degree and ar-
York 1828, Germany 1830, and Austria 1843. rangement of the unsaturated double bonds in the
The date of the first use of oil in paints has been fatty acid; drying rate and time; solubility in com-
lost in obscurity. The earliest paints were little more mon solvents; miscibility with other oils; skinning
than colored rock or clays dispersed in plant juice, time, stability in storage; stability under heat, flow,
milk, egg white, natural glues, animal and/or vege- leveling, break, and wetting characteristics.
513
514 TIIE JOURNAL OF THE AMERICAN 0IL CHEMISTS' SOCIETY, NOVEMBER, 1950

Purpose oil film. Important in all films where unprocessed oils are
used and may be important in many processed oils.
I t is the p u r p o s e of this p a p e r to p o i n t o u t the oils 8. Some fihns of oil, more than others, show as a result of
t h a t are used i n t o d a y ' s o r g a n i c finishes. W e will continued reaction in the oil film, after it sets, a decided
confine most of our discussion to the c o n s i d e r a t i o n of tendency to yellow. They are said to have bad color retention.
the direct a p p l i c a t i o n s to p a i n t s a n d n o t u n d u l y em- The type of unsaturation and the amount of the unsaturates
are important in estimation of the change in color in varnish,
phasize the i m p o r t a n t a n d w i d e s p r e a d uses of oils i n lacquers, paints, and enamels, especially white and tints.
the m a n u f a c t u r e of v a r n i s h a n d s y n t h e t i c resin, ex- 9. Oils which are blown with air at 200-400~ for several
cept where t h e i r p r o d u c t s are used i n p a i n t s . W e hours show the effect of oxygen attack on the double bonds by
shall briefly call a t t e n t i o n to the composition of the an increase in viscosity, deepened color, low solubility in non-
polar solvents, and greater reactivity with basic pigments.
oils so as b e t t e r to a p p r e c i a t e the uses of oil w h e t h e r Blown oils have reraarkable wetting characteristics but are in
it is raw, refined, treated, modified, i m p r o v e d , or many properties inferior to kettle bodied oils.
synthetic. 10. Oils which are heat bodied in the absence of air show
I n the fihn the d r i e d oil p r o p e r t i e s such as h a r d - a gradual increase of viscosity which eventually leads to a
solid gel where the oil molecules are united at the double bonds
ness, flexibility, elasticity, resilience, color, color through primary valences without any intermediary oxygen
r e t e n t i o n , p e r m e a b i l i t y to fluids, w a t e r p r o o f n e s s , ad- linkage. These oils show improved properties over those of
hesion, s o l u b i l i t y , resistance to u l t r a v i o l e t light, the raw oils. These oils have better flow and leveling char-
resistance to acids a n d alkalies, gloss r e t e n t i o n , bleed- acteristics. The fihns dry harder and faster. The films are
glossier and generally have improved resistance to the weather
ing, resistance to h e a t a n d a b r a s i o n , t r a n s p a r e n c y , and wear. The bodying of the oil permits the addition of
coefficient of e x p a n s i o n f o r c o n d i t i o n s u n d e r which volatile thinner without unduly lowering the viscosity.
used, a n d other p r o p e r t i e s for specific a p p l i c a t i o n 11. The raw oils may be used without the addition of undue
m u s t be m e t if the oil is to meet with w i d e - s p r e a d amounts of volatile thinners.
12. Many raw oils are unusable without kettle treatment
favor. The c o n t i n u e d use of oil i n a p a i n t vehicle or blending.
w i t h o u t d o u b t m u s t reflect the fact t h a t the above 13. Evidence points to the mixed triglyceride molecular
m e n t i o n e d economic a n d t e c h n i c a l f a c t o r s have i n a structure of drying oils. A mixed triglyceride structure gives,
large m e a s u r e b e e n met. W i t h few exceptions science during fihn formation, a more homogeneous structure to the
film and improved characteristics among which are waterproof-
has f o u n d other m a t e r i a l s t h a n oil, which excel i n hess and wear.
one or more of the l i q u i d or film properties, b u t these 14. The general utility of the oll is dependent upon the
competitive m a t e r i a l s are deficient i n other c h a r a c t e r - number of fatty acids which enter into the structure of the
istics, a n d , i n a d d i t i o n , lack the a b i l i t y to meet the mixed triglyceride molecules in any oil. Thus two fatty acids
make possible a maximum of six theoretical triglyeeride struc-
overall desirable a n d w e l l - r o u n d e d c h a r a c t e r i s t i c s of tures. The number increases rapidly with each additional fatty
n a t u r a l or processed oil. Not all oils meet all of these acid found in an oil and the type of unsaturated system.
properties, some are s u p e r i o r i n c e r t a i n p r o p e r t i e s
b u t less s u i t a b l e i n others. A t this p o i n t it is well to Let us consider the oils s e p a r a t e l y a n d note t h e i r
p o i n t out t h a t the selection of a n oil for a p a r t i c u l a r a p p l i c a t i o n i n p a i n t s . M a n y of the c h a r a c t e r i s t i c s of
f o r m u l a t i o n is n o t g e n e r a l l y b a s e d u p o n a single fac- the p a i n t film are n o t e d f o r each t y p e of oil i n i n d i -
tor b u t is a c o m b i n a t i o n of b o t h the t e c h n i c a l a n d v i d u a l f o r m u l a t i o n s or d r i e d films.
economic factors. I n some i n s t a n c e s the economic
Linseed Oil
f a c t o r is p a r a m o u n t . E c o n o m i c a l l y i n some instances,
it is d e s i r a b l e to use a h i g h - p r i c e d t r e a t e d oil while The c o n s u m p t i o n of linseed oil i n the U n i t e d States
i n others a lower p r i c e d oil as s o y b e a n or tall oil m a y is more t h a n t h a t of all other vegetable oils combined.
be e n t i r e l y satisfactory. A delicate p o i n t f o r the m a n - A l t h o u g h l i n s e e d oil was n o t the first v e g e t a b l e oil
u f a c t u r e r to decide a t this p o i n t is w h a t to offer i n to be used b y p a i n t e r s a n d c r a f t s m e n who p r e p a r e d
competitive b i d d i n g on a p e r f o r m a n c e specification t h e i r own p a i n t y e t its p h y s i c a l a n d chemical prop-
request. erties, t o g e t h e r with its a g r i c u l t u r a l p o t e n t i a l i t i e s ,
Since it is the f u n c t i o n of this p a p e r p r i m a r i l y to q u a n t i t y p r o d u c t i o n , a n d the p r o d i g i o u s a m o u n t of
p r e s e n t the uses of the oils i n p a i n t s , sufficient t h e o r y research which has b e e n d i r e c t e d t o w a r d its utiliza-
has b e e n p r e s e n t e d b y p r e v i o u s speakers to direct tion, have m a d e linseed oil the s t a n d a r d of compari-
a t t e n t i o n to the s t r u c t u r e of the oil molecule a n d the son to e v a l u a t e other d r y i n g oils.
possible reactions of the oil i n d r y i n g t h a t we m a y I n 1938, 821/2% of all d r y i n g oils c o n s u m e d i n the
now m e n t i o n other c h a r a c t e r i s t i c s of oils: U. S. was l i n s e e d oil. Of the a m o u n t 61% was proc-
1. All natural drying oils contain variable amounts of sat- essed i n factories, a n d the balance, 39%, was used
urated fatty acid chains which do not dry but are important m o s t l y b y p a i n t e r s i n the p r o d u c t i o n of mixed-on-the-
considerations in plasticizers to decrease hard setting. j o b - p a i n t s . A b r e a k d o w n of the 61% reveals t h a t the
2. All natural drying oils contain unsaturated double bonds. p a i n t a n d v a r n i s h factories are 45.5%, the l i n o l e u m
3. All natural drying oils are esters, thus are capable of
being saponified, and as a consequence they are not very alkali- a n d oil cloth i n d u s t r y 11.9%, a n d the p r i n t i n g ink
resistant. Important in polymerization and drying and will i n d u s t r y 3.6%. T o d a y w i t h the s h i f t f r o m mix-on-
help in determining type of finishes which may be formulated t h e - j o b - p a i n t s to r e a d y - m i x e d p a c k a g e d p a i n t s the
with them. p e r c e n t a g e of f a c t o r y c o n s u m e d l i n s e e d oil has in-
4. Most natural drying oils contain an insufficient number
of unsaturated double bonds. Important in drying, plasticiz- creased to 93% of the total. A c o m p a r i s o n of the fac-
ing, and polymerization. t o r y d r y i n g oil c o n s u m p t i o n for the y e a r s 1938 a n d
5. Most natural drying oils contain the unsaturated double 1949 i n d i c a t e the shift f r o m a one- or t w o - p i g m e n t
bonds in unfavorable positions. Important consideration in m i x - o n - t h e - j o b - p a i n t w i t h linseed oil as the vehicle to
determining the type and extent of polymerization, processing
of oils, and characteristics of the drying oil film. a m u l t i p l e p i g m e n t p a i n t of v a r i e d vehicles.
6. The triglyeeride structure prevails in natural drying oils B y f a r the g r e a t e s t a m o u n t of l i n s e e d oil is con-
and is not the most desirable under all types of application of s u m e d i n outside house p a i n t s . I n this field it has few
the oil in protective coatings, alkyds, varnish, and synthetic peers. I t s few weaknesses are u n i m p o r t a n t . These
resins. are offset b y its well r o u n d e d b a l a n c e of l i q u i d a n d
7. Once a fihn of oil has dried hard, the reactions within the
oil fihn do not stop but continue and eventually destroy the film characteristics.
 TIIE JOURNAa OF TI~E A~RICAN OIL CHEMISTS' SOCIETY,NOVEMI~ER,1950 515

Raw linseed oil tops the list of all vehicle compo- Linseed Oil Alkyds
nents in one property, the wetting of ferrous surfaces. Linseed oil alkyds are used in under water primers
It is the most used single vehicle for primer or shop because of the excellent adhesion.
coats on structural steel. On sandblasted, flame Long oil linseed alkyds are used in exterior house
brushed, or even the ferrous surfaces where only the paints, trim paints, and exterior enamels. The use of
very loose mill scale has been removed, the oil im- alkyds provides excellent gloss and color retention
pregnates the rust and affords an almost perfect and durability under trying Conditions. The use of a
wetting on all these types of surfaces and, upon dry- little heat bodied oil with alkyds in trim paints ira-
ing, a most adhesive film. proves flow, levelling, and brushing qualities.
Raw linseed oil in combination with red lead and Linseed alkyds of the proper oil length are used in
zinc dust has remarkable adhesion to cleaned and aluminum paints, heat resisting zinc dust paint,
unweathered zinc or galvanized surfaces. primer paint, grinding and flushing liquids, water
Because of the well rounded properties, universally resistant paints, fast drying primers and paints, out-
known characteristics, and availability of raw linseed side house paint, white and colored enamels, auto-
oil, methods have been developed to treat it, retiree motive primers, maintenance paints, porch and floor
it, modify it, improve it, blend it, combine it chem- paints, traffic paints, railway paints, red lead primers,
ically with other materials, and adapt it to almost ink and coatings for silk screens.
every possible protective coating problem. Linseed Alkyds may carry a blend of linseed and soybean
oil satisfies more of the requirements of the protective oils to produce vehicles for special primers and enam-
coating industry than any other single oil. This is in els for automobile refinishing.
spite of its somewhat slow drying rate; undesirable Linseed alkyd finishes with respect to hardness,
yellowing characteristics; its water permeability as flexibility, and general resistance to wear are among
compared to some varnishes and synthetics; struc- the f n e s t vehicles used in protective coatings. The
tural disadvantages like saponifiability; continued alkyd after production retains the stamp of the orig-
oxidation after the original " d r y h a r d " of the film, inal oil in appearance, odor, taste, and most of the
and poor Color retention. original oil's physical and chemical properties. Only
Raw or refined linseed oil blended with 10-15% in drying and bodying do they show noteworthy dif-
soybean oil gives an excellent mixture, which dries to ferences from their parent oil.
a homogeneous fihn. The fihn is more elastic and will
Blown Linseed Oil
not t u r n brittle under conditions that would effect a
film of 100% pure linseed oil. Such oils may collect Although blown or oxidized linseed oils are inferior
a little dirt. in many characteristics to heat bodied oils, yet their
outstanding pigment wetting characteristics h a v e
Raw or refined linseed oil may be blended with made them a desirable additiori to poorly-wetting Ve-
50% or less of dehydrated castor oil to overcome its hicles. They also improve flowing and levelling prop-
poor drying characteristics and tackiness. The film
erties of vehicles at lower cost than b y the use of
of the blend still retains the water-resistance prop-
bodied oils. Since they have a viscosity Y to Z~, they
erties of DCO. Raw or refined linseed oil has been must be cut with sufficient thinner to reduce the vis-
blended successfully with sesame, hempseed, sun- cosity to the desired workable viscosity. Blown castor
flower, safflower, raisin seed, and walnut oils in the
oil added to blown linseed oil improves flowing char-
preparation of an outside house-paint vehicle. The acteristics, increases gloss, and brilliance of film and
linseed oil should have a high iodine number, and the
imparts flexibility to the dried film. These oils have
percentage of these oils should be about 18-25% of been used in semi-flat paints where the color is of no
the oil blend.
importance. Blown linseed may be used in the formu-
Acid Refined Linseed Oils lation of flat oil paint vehicles.
I f the linseed oil is blown to a viscosity B to E,
Acid refined linseed oil is used as a grinding oil for
acid No. 2-6 may be used in printing inks, litho-
pigments. The viscosity is usually less than A
graphic varnish, patent leather finishes, and with
(G.H.S.). I t wets pigments readily and produces elastic transparent films of high gloss. They are also
paints with the characteristic brushability demanded
used in low grade enamels with "gloss oils."
by painters. It may be almost colorless hence it does
not affect the color of white or delicate tints. The low Bodied Linseed Oil
acid numbered oil is especially adapted for grinding The heat bodying, heat polymerization or kett!ing
zinc or titanium pigments. The high acid number of oils is probably the oldest and most widely used
9-16 of acid refined linseed oil is used to produce method for modification of raw or refined oils. Bodied
puffy paints. It reacts during dispersing with white oils, or stand oils as they are called, retain to a large
lead, producing lead soaps which serve as the skeleton degree the properties of the oil from which they are
to prevent rapid settling.
made, but all bodied oils have certain properties pe-
Acid refined oils with acid number, 1~5, are used culiar to the process. The oils have an acid value
as a grinding oil with excellent wetting and levelling which range from 1 to 22 and viscosity of O to Z9 or
properties which are used to form films of high luster. may be bodied in the presence of an inert atmosphere
The acid refined oil is suited for grinding zinc oxides a n d / o r under vacuum. Due to their increased molec-
and other reactive pigments. ular complexity the impermeability of the oil film is
Acid refined oils may be blended with 10% heavy greatly increased and penetration into substrate is
bodied oil to produce enamel grinding oils, which markedly decreased. These heat bodied oils, 10-15,%,
have excellent brushing qualities, yielding brilliant are added to outside house paint vehicles to increase
light colored films suitable for the highest grade Of brushability, flow, levelling, hardness, faster drying,
enamels. better gloss; to improve resistance to water and
516 THE JOURh'AI~ OF THE AMERICAN OIL CHEMISTS' SOCIETY,NOVEMBER,1950

weather; and to decrease corrosion of ferrous are incorporated b y means of heat, the oil m a y have
supports. a high acid n u m b e r hence it should be used with non-
They m a y be used in p a i n t vehicles to increase reactive pigments to reduce livering.
wetting characteristics and improve the resistance of Combined with limed rosin it makes an economical
the film to w a t e r and alkali. F o r economic reasons a interior paint vehicle.
blend of raw linseed oil, heat bodied linseed oil, and Boiled oils m a y be had which will dry, in either
mineral spirits in equal volumes makes an excellent 12-14 hours or in four hours. The 10-14 hour drying
vehicle for paints without a n y sacrifice in consistency. boiled oils are used with slow-drying black pigments.
D u r i n g the interval 1941-1949 the use of heat-bodied The four-hour drying boiled oils m a y be used with
oil has increased f r o m 7% to 67%. advantage in hard-to-dry black pigments or railroad
H e a t bodied oils are used in w a t e r emulsion paints. and bridge paints.
A heat bodied oil (stand oil) made b y the interaction The boiled oils which have an acid n u m b e r of 6-8
of t u n g oil and linseed oils during the bodying has and a light color m a y be used for grinding and letting
superior properties and is used as a high grade ex- down white and light tint finishes, which are usually
terior paint vehicle. The v a c u u m bodied oils have an brilliant and lustrous films.
advantage over open kettle polymerized oils in t h a t
they have lower acid n u m b e r and facilitate the re- Alkali Refined Linseed Oil
moval of decomposition products. The light bodied Alkali refining of raw linseed oil removes most of
oils of viscosity X to Z 6 are used in paints and the free f a t t y acids, b r e a k (sugars and mueilagenous
varnish. material), sterols, color, and other objectionable im-
The polymerized oils with acid No. of 7-10, viscosity purities. This oil is used as a component of low acid
Z,~-Zs, on addition of 10-15% by weight of paints im- vehicles. Retention of color u n d e r heat and normal
prove the gloss and d u r a b i l i t y of the dried fihns. conditions, better initial color, together with its low
Polymerized oils produced in hermetically closed acid value makes alkali-refined linseed oil a favorite
kettles with a small outlet under a blanket and cur- in varnishes, a n d a source of linseed oil f a t t y acids
rent of COs to remove decomposition gases, without or the monoglycerides of linseed oil in the production
exposure to air, yield bodied oils the same as open of alkyds. The viscosity of alkali refined oil is not
kettles with an acid n u m b e r of 6 to 18 and viscosity very different f r o m the raw oil used in its production.
of Q to Z 4. These oils are used to produce over-night The alkali refined linseed oil has little dispersion
drying wood fillers, in which the oil will remain dis- action on pigments.
persed in the filler, while an o r d i n a r y oil would leave This oil is recommended f o r the formulation of
the surface with very little oil dispersed in the filler. white paints, white enamels, light colored varnishes,
Vehicles for non-ferrous metal paints which con- alkyd resins of low color, low acid n u m b e r p r i n t i n g
tain bodied oil in conjunction with treated linseed inks, grinding oil for basic pigments and allied
oil are used to increase the adhesion. products.
Soybean Oil
Replacement oil made according to Federal Specifi-
cation TT-O-371, which is 1/3 heat bodied oil; 1/3 Soybean oil is a young rival of linseed oil. I t is a
raw or boiled linseed oil and 1/3 naphtha, is an ex- good example of the m a n n e r in which the paint and
cellent article deserving of special mention as it has varnish industry has seized upon a domestic oil, avail-
placed a scientifically heat bodied oil into the hands able in great quantities at a low price, and has
of home painters. The replacement oil in some re- adapted it to its use. An examination of the char-
spects is better than vehicles composed f r o m boiled acteristics of refined soybean oil discloses the fact
raw, or alkali refined linseed oil. I t has more elastic- that its films d r y slowly and are quite soft, but on
ity, is more durable, more water-proof; and less de- the other hand the films have increased flexibility,
pendent upon the vagaries of raw agricultural crop less checking and less brittleness, b e t t e r color and
products. The irregularities in linseed oil f r o m crop color retention than linseed oil films. Tackiness and
to crop are equalized b y the heat bodying process. stickiness of the oil film is most noticeable in reaction
I f the raw oil is extended to 75% of the non-volatile pigments, which f o r m slow and soft drying soaps.
of the blended oils, the p r o d u c t has lost practically Raw soybean oil is of little use in p a i n t fihns be-
all its merit. cause it sets in more than twice the time required b y
a linseed oil fihn. Although the film a f t e r it has set
Boiled Linseed Oil is quite durable, it is so soft that it freely collects
Boiled linseed is produced f r o m raw or alkali re- dirt, supports mildew growth, and soon becomes un-
fined linseed oil b y the incorporation of 0.2% metals sightly. Unmodified soybean oil bodies very slowly
as Pb, Mn, CO, Zn, etc., b y means of agitation of in the varnish kettle even at 600~ The oil becomes
soluble, stable metal compounds or b y means of a d a r k and has a high acid number. I n spite of the poor
combination of heat and agitation. These oils d r y in showing of raw soybean oil it is of special interest
about one-tenth the time of raw linseed oil and are since it contains less t h a n 7% linolenic acid.
employed in either interior or exterior paints. They Alkali refined soybean oil is used in house paints
have a viscosity range of A to B (G.H.S.). They m a y without impairing the useful life of the paint film,
be used in place of raw oil and dryers. The oil is b u t its films collect dirt readily and in most ways re-
practically free of moisture, and color is darker t h a n tain essentially the drying characteristics of raw soy-
the color of the oil f r o m which it was processed. bean oil. I n general, the direct substitution of soy-
Bodied oil exhibits quick set, controlled flow, good bean oil for linseed oil in a paint retards the d r y i n g
durability, better color retention and water resistance rate to a degree that is a p p r o x i m a t e l y proportional
than raw linseed oil in outside house paints. I t is to the amount of oil substituted, b u t once the film is
used to add to exterior paints as the p a i n t e r does not dry, its d u r a b i l i t y compares f a v o r a b l y with that of
need to consider drier addition. I f the metallic salts a linseed oil house paint film except for the increased
 TI~E JOURNAL OF THE AMERICAN OIL CHEMISTS' SOCIETY, NOVEMBER, 1950 517

dirt collection and increased mildew susceptibility. drying time and less yellowing than linseed oil films.
In paint vehicles small amounts of soybean oil, 15- The dirt collection and mildew tendency (due to soft
20%, substituted for linseed oil do not seriously affect films) are almost directly proportional to the unal-
the drying time but materially improves the flexibil- tered soybean oil remaining in the modified oil. The
ity. With perilla-soybean oil blends large additions tendency toward cracking and flaking are greatest in
of soybean oil are possible. A 15-20% blend of alkali the most highly altered oil. Maleie anhydride-soybean
refined soybean oil and linseed oil is an excellent ve- oil has been used successfully in barn and traffic
hicle to use in grinding colors which will keep in- paints..
definitely without skinning or becoming hard. Refined Some soybean oil alkyds show after-hazing on in-
soybean oil does not break below 600~ terior use. This can be reduced by combining part of
The different kinds of oils will vary in color and the soybean fatty acids with pentaerythritol rather
color retention. Soybean oil excels in these char- than polyhydric alcohol, which contains fewer OH
acteristics, followed by perilla, linseed, and fish oils. groups. It requires the production of more complex
In the oil conservation type of paint vehicles the structures to prevent the non-drying radical migra-
replacement of part or all of the bodied linseed oil tion. Such a migration is manifest in the film by a
with bodied soybean oil of equivalent acid number reduction of gloss. If all the free fatty acids are re-
gives results which appear to be as satisfactory as moved from the finished alkyd, "after-hazing" is re-
those obtained with the corresponding linseed oils. duced to a minimum.
The higher pigment volume used in these paints and The soybean alkyd is added to lacquer to increase
the slower drying are not as apparent, and the higher gloss and elasticity in place of castor oil; to asbestos
rate of chalking under normal exposure conditions type coatings as a softening agent; to high temper-
makes dirt collection much less serious. The tendency ature baking oils and Japans to increase elasticity;
to crack increases with increasing body of the soybean to gloss finishes and enamels to improve brushing,
oil if the comparison is made at equal volume wetting, and flow. It is also used in making many
relations. alkyd resin solutions which are used in enamels of
Where bodied soybean oil is to be a part of a ve- excellent weather resistance; vehicle for primers, and
hicle, more satisfactory results are obtained by co- finishes to be applied by brush, spray, roller coating,
polymerization with other oils than by blending the or dipping. Other alkyd vehicles uses are architec-
bodied oils which have been bodied separately. tural, stone house trim, sign paints, marine paints,
Although a blend of soybean and perilla oils in the traffic paints, lithographic coatings, porch and floor
ratio of 1:2 bodies slowly, the bodied product equals paints, spar and overprint varnishes, collapsible tub-
equivalent linseed oil in drying characteristics and ing coatings, pigment grinding, chill back oil, re-
may be used in place of a similar grade of linseed oil. l~lacement of bodied oil, and government specifications
Tung oil bodied with soybean oil yields a bodied as 52R13a, types I and II. It may be blended with
oil which is said to be free of the defects of either nitrocellulose lacquers, or acid-catalyzed urea formal-
original oil. Should the soybean oil be prebodied be- dehyde resin to meet the requirements of forced-dry
fore the co-bodying with tung oil, it has been shown production lines of the automotive o r furniture
definitely to shorten the drying time of the final industries.
bodied oil. Tung or oiticica oil varnish fihns which By the proper selection or balance of pigmentation
tend to become exceptionally brittle on exposure will pure refined soybean oil may be used in paints which
have this tendency minimized, and the durability will dry to a film free from dirt collection and mildew
be improved without hindering other properties of tendencies on outside exposure. After-tack in the soy-
the varnish if some soybean oil is used to replace a bean oil film may be eliminated almost entirely by the
portion of either conjugated oil. addition of small amounts of calcium oxide, and the
Oxidized or blown soybean oil has many favorite durability of the film is improved. The formulation
uses, among which are printing inks, linoleum, oil must be such that it will balance the defects : slow
cloth, treated fabrics, leather dressing, pigment drying films and soft drying of refined soybean oil
pastes, and lithographic varnish. The blown soybean films ; and the tendency of bodied soybean oil to crack
oils do not dry out as brittle as the blown linseed oils. and flake with the inelastic-hard-dry adhesion of
The blowing of soybean oils increases the hydroxyl other oils and the proper balance of soap forming
uumber, which contributes to its increased solubility pigments.
in alcohol and a reduction in solubility in mineral Soybean oils in the proper form may be blended
spirits, but the blown oil is never completely insol- with linseed, perilla, oiticiea, dehydrated castor oil,
uble in mineral spirits because of saturated fatty fish oil, and tung oil in the manufacture of house
acids or their glycerides. The heavier bodied blown paints, varnish, baking Japans, baking finishes for
oils are used in inexpensive paints and enamels, putty, automobile, refrigerator, and various drying syn-
caulking compounds, and inexpensive plasticizers. thetic finishes. In most instances alkali-refined oil is
Films of soybean-tung oil blends of a 67:33 ratio preferred.
dry at approximately the same rate as a bodied lin- Soybean oil is used in shingle stains as the non-
seed oil of the same viscosity in paint films, but volatile portion of the vehicle. In caulking com-
slightly slower in varnish films. Oils of this blend pounds its slow drying properties are valuable.
have practically the same water resistance in films
as linseed oil films. Castor Oil
Soybean oil which has been treated by trans- Raw castor oil is not classed as a drying oil or used
esterifieation with pentaerythritol, or with maleic an- in protective coatings except as a plasticizer for lac-
hydride and styrene to produce a modified soybean quers, leather dressing dopes, or like formulation.
oil has been found to have less dirt collection and The dehydration of raw castor oil changes it from
certain other desirable properties, such as shorter a non-drying oil to a drying oil with most of the
518 THE JOURNAL OF THE AMERICAN OIL CHEMISTS' SOCIETY,NOVEMBER, 1950

ricinoleic acid converted to a linoleic acid, which in: enamels to be used in both air and baking finishes.
eludes 20-25% of conjugated isomeric linoleic acid. Higher viscosity alkyds may be prepared from me-
The drying time and water resistance of dehy- dium and long oil DCO alkyd resins than from linseed
drated castor oil (DCO) ranks between that of ttmg alkyd resin of similar composition. In short, oil alkyd
oil and linseed oil. It bodies in one-quarter to one- resins to obtain a high viscosity p a r t of the DCO must
third the time of linseed oil under the same conditions. be replaced with f a t t y acids from oils like sunflower
I~ilms of dehydrated castor oil do not whiten on ex- or soybean oil. The f a t t y acids from both oils con-
posure to moisture like linseed oil films, b u t they tribute to the qualities of the short oil alkyd resins;
swell under water more than tung oil. The film color the DCO contributes cooking and drying speed
is superior to tung or linseed oil films. The dehy- whereas the slow d r y i n g oil holds back the polyme r -
drated castor oil films are characterized by non- ization long enough for the acid value to reach a
yellowing, odorlessness, good durability, good wet- minimum.
ting, non-livering tendencies, good color, good flow, Alkyd resins also make excellent under-water pri-
good adhesion, and little after-tack. The dried fihn mer vehicles in conjunction with 97% red lead.
of DCO is more flexible and elastic than tung oil Dehydrated castor oil may be gelled and then dis-
films, and unlike oiticiea oil films it does not become persed in unbodied oil for the manufacture of under-
brittle on aging and has a durability, considered b y coat and enamel vehicles.
some as equal to tung oil. The film of DCO does not
dry as h a r d ultimately as linseed oil or perilla oil Bodied DCO of low, medium, and high viscosities
films. Properly formulated and cooked dehydrated are being successfully used in paints and enamels.
castor oil vehicle films do not frost or wrinkle or web These products d r y quicker, have better color reten-
on exposure to gas fumes in the manner characteristic tion, greater resistance to water, and possibly g r e a t e r
to tung oil. durability than their linseed oil counterparts.
The above properties are responsible for dehy- In varnishes which contain linseed oil, rosin, phe-
drated castor oil becoming a favorite for the produc- nolic resin, or zinc resinate with dehydrated castor
tion of alkyd resins and varnish in which after-tack oil it has been found to be advantageous to replace
is overcome. Its non-yellowing characteristics, either up to 40% of the DCO with perilla, new fish oil prod-
in air drying or baking, assures it broad application ucts, or tung oil to increase hardness in the vehicle
in varnish employed in formulation of interior gloss intended for high gloss, eggshell whites, and colored
paints and enamels. A 15-20 gallon length DCO var- enamels for both air drying and low temperature
nish makes very good clear automobile enamels. baking finishes.
Dehydrated castor oil is not a direct substitute for Many modified phenolics, especially phenolic modi-
tung oil because of the slow drying and its retention fied alkyd resins and polybasie acid phenol resins,
of surface tack for several hours. Hence it is difficult are well adapted for cooking with DCO. They cook
to use in the formulation of rubbing varnishes or in a short time at 550~ without danger of prema-
baking varnishes or enamels where absence of resid- ture gelation. Where the highest weather resistance
ual tack is important. and chemical resistance are important in vehicles con-
Alkyd resins made with DCO are used in refriger- taining DCO, a 100% phenolic resin should be em-
ator finishes beeause of its paleness and non-yellowing ployed. If the resin is highly reactive, care must be
qualities. Some medium oil length DCO alkyds are exercised as excessive bodying may cause gelation in
plasticizers for nitrocellulose lacquers, urea, or mel- the kettle.
amine resin enamels, polyvinyl chloride and chlori- Maleic modified DCO is well adapted for interior
nated r u b b e r coatings, where toughness, adhesion, enamel vehicles because of its whiteness, color reten-
gloss, and weather resistance are important. Alkyds tion, and high gloss, air drying and low baking prop-
are also used in white baking enamels on refrigerators erties. If the vehicle is too long and is overcooked to
and ranges when modified with urea or melamine obtain the required body, more resin should have been
resins. used because there is a tendency to after-body, which
Medium oil length DCO alkyds modified with rosin may lead to gelation in the case of either pigmented
are used in baking enamels for home appliance pri- and unpigmented products.
mers where high humidity, moisture resistance, and The best baking enamel finishes containing DCO
adhesion are important. They may also be used in arc blends of DCO and some other appropriate oil to
arehiteetural and decorative finishes and in mixing meet the baking characteristics required in the
varnish. vehicles.
Dehydrated castor oil alkyds give better total im- Oiticica Oil
mersion in salt water than linseed or soybean oils Brazilian oiticica oil is quite similar in many of its
because of their non-yellowing and their imperme- characteristics to tung oil. I t has been on the market
ability to water, fast drying, and good color retention, about 20 years, and its possibilities have not been
which were previously associated only with slow dry- fully explored. The desirable properties of oiticica
ing alkyds of the sunflower oil type. oil are attributed to the high content of keto-eonju-
Short oil DCO alkyds used with or without urea or gated-lieanic acid. Raw oitieiea oil dries to an opaque
melamine resins are valuable vehicles in enamels for wrinkled film similar to tung oil films. The drying
metal furnishings, automotive finishes, e n g i n e s . rate is exceeded only by t h a t of tung oil. Large
pumps, signs, primers and surfacers for metal and quantities of oitieica oil are consumed b y the protect-
plastics, force d r y sealers and varnishes. ire coating industry where it dries hard and more
Alkyd resins made from the distilled f a t t y acids of gas-proof than tung oil but has the disadvantage of
DCO surpass the non-yellowing and drying properties darkening on heating; on drying its aged films are
of linseed and soybean distilled f a t t y acid alkyd resin. brittle and less waterproof. F o r severe exterior uses
They are suitable for clear coatings and white and high water and chemical resistance the use of
 TtIE JOURNAL OF THE AMERICAN OIL CHEMISTS' SOCIETY,NOVE:MBER, 1950 519

oiticica oil is limited. P u r e oiticiea oil films yellow Chinese tung oil may be stored f o r long periods of
hence color must be considered in formulation. time without apparent deterioration, but the domestic
It gells more slowly than tung oil. Gelled oiticica tung oil must he used within a comparatively short
oil may be dispersed in unbodied oil to use in under- time to avoid storage losses.
coat and enamel vehicles. It lacks petroleum tolerance. The rapid bodying of tung oil is controlled in the
Oiticiea oil is used primarily in varnish. Ten to varnish kettle b y the addition of non-conjugated oil
40% of oitieiea oil, depending upon the performance as linseed, soybean, fish oil, and many other non-
required, may be substituted for tung oit in many conjugated oils. Tung oil which is heated to 5 5 0 ~
varnishes. Whenever oiticica oil replaces tung oil in for 5-8 minutes is gas proofed and also has several
rosin, estergum, cumarone-indene or modified phe- other desirable properties, such as increased acid and
nolic resin varnishes, the drying time is retarded and alkali resistance, which offset the undesirable char-
the water and chemical resistance is lowered. I f acteristics of raw tung oil in many of its uses.
100% phenolic resin is cooked with 100% oiticiea oil, Most of the tung is preferably modified by con-
the varnish produced has exterior exposure resistance version into stand oil or b y incorporation with resins
equal to similar tung oil varnishes. into varnish or blending with non-conjugated vege-
Oiticica oil reacts more rapidly with pure alkyl table oils such as linseed, soybean, fish, sunflower, and
phenolic resins than tung oil; is inferior to tung oil safflower oil. Stand oils in which tung oil is combined
for durability in cheap boat varnishes; is used as a with linseed, perilla, or similar oils yield products to
component in oleoresinous vehicle to produce crystal, provide excellent flow, good gloss, rapid dry, and ex-
crackle, and wrinkle finishes. Oleoresinous vehicles cellent water resistance are used in high gloss paints
containing oiticica oil and alkyds are blended to con- and controlled penetration, one-coat paints.
trol a definite wrinkle p a t t e r n in wrinkle finishes. The Tung oil makes possible the preparation of spar
oil is employed only to a small degree in white gloss varnish from estergum, ~pheuolic resin, hardened
paints, enamels, and flat paints, owing to the greater rosin. Oxidized tung oil varnish films have high in-
yellowing than linseed and tung oils. It may be safely sulation properties. Alkyd resins containing tung oil
used in dark tints. are used in finishes which are air dried and must
Oiticica oil forms very stable emulsions when mixed show characteristics of toughness and hardness. Can
with aqueous solutions. It has been suggested as a and wire enamels are made from 15-30 gallon tung
plasticizer in waxes and polishes. The brittleness of oil varnishes which contain Congo or pure phenolic
oiticica oil vehicle films may be reduced b y the sub- resins. Beer cans may be covered with a varnish com-
stitution of linseed or similar oils for part of the posed of tung oil-rosin maleic glycerin esters. Tile
oiticica oil. liquefied gel of tung oil is unsuitable f o r good var-
Tung Oil nishes b u t may be used in cheap varnishes.
The outstanding drying characteristics of tung oil Perilla Oil
are for the most part attributed to the fact that the
oil has 80-90% eleostearic acid, which has three un- Perilla oil has the highest iodine number o f all the
saturated double bonds in a conjugated system per raw non-conjugated drying oils. It has excellent dry-
mole of acid. ing properties, which lie between those of tung and
The eleostearie acid is considered as the p r i m a r y linseed oils. It has high surface tension and creeps
reason for the very good waterproofness, raPid dry- when spread in thin films. If heated to 500~ for a
ing, hard drying, excellent durability, and chemical short time, the surface tension and yellowing tend-
resistance of tung oil films. Tung oil films are highly encies are reduced. The oil dries to a brilliant, hard,
resistant to saponifying agents. The oil bodies rap- tough, and fairly waterproof fihu. The bodying rate
idly and has great compatibility with various natural of perilla oil is almost twice that of linseed oil b u t
and synthetic resins used in varnish manufacture. has a greater tendency to yellow, especially on bak-
ing. It has a lower flash point than most oils. :The
The use of raw tung oil in paints is definitely lim- odor is pleasant.
ited b y the fact that it wrinkles on drying and may Perilla oil is used to f o r t i f y linseed oil, soybean oil,
cause frosting, dull appearance, low elasticity, web- and semi-drying oils and to make blended oils which
bing and checking in films of the customary thickness simulate linseed oil in drying characteristics. A non-
used in paint films. It may wrinkle in the can. The break perilla oil is used to substitute for linseed oil
fact that raw tung oil dries with a " m a t t e " or shriv- or tung oil in varnishes which require less drier and
elled appearance is utilized as a valuable asset in the have good color retention. Blown perilla oil is noted
production of wrinkle or crystalline finishes and also for its rapid drying, the hardness of its film, and re-
helps to control the pattern in baking wrinkle finishes. sistance'to weathering.
Raw tung oil may be used in traffic paints to plasti- I t has been used to produce alkyd resins and is
cize, increase adhesion and waterproofness of hard considered b y some a favorite in varnish making.
drying butadiene styrene resin vehicles. Raw tung Perilla oil may be gelled, a n d ' t h e n the gelled o i ! m a y
oil is used in the formulation of concrete paints. be dispersed in unbodied 0il for use in the manufac-
Tung oil blended with linseed oil in the ratio of ture of undercoat and enamel vehicles. I t is used in
1 to 3 is a good paint vehicle. Tung oil may be the production of printing inks. It has been sty-
blended with perilla, soybean, and fish oil in prepara- renated to form modified oils. T h e oil is being used
tion of outside house paint vehicles. Blends of tung less today because of cost and supply factor.
oil with non-conjugated oils are used in the produc-
tion of shellac, synthetic, natural resin, and as- Fish Oils
phaltum varnishes to impregnate paper, fabrics, and The principal marine oils which are of special in-
fiber board. T u n g oil is blended with DCO and other terest to the paint manufacturers are menhaden,
oils to control the gas proofing more easily. salmon, and sardine oil. Unlike other paint oils, these
520 THE JOURNAL OF TttE AMERICAN OIL CtlEMISTS' SOCIETY,NOVEMBER, 1950

oils have some tetra- and penta-functional acid chains fish oils are used in stock pastes and colors in oil and
which are extremely fast drying. These oils have ex- paste paints because of their non-skinning, color re-
cellent adhesion, elasticity, and durability. They are tention, color, absence of after-yellowing, and clarity
not as water-resistant as tung oil, b u t because of their of tints.
elasticity and adhesion the water resistance is better Tall Oil
than commonly used oils. Their wetting properties Tall oil, a by-product of the sulfate pump industry,
for equal body are,superior to those of vegetable oils. is composed of 45-50% f a t t y acids (principally oleic
Refined fish oils have relatively good non-yellowing and linoleie acid), 42-48% rosin acids, a n d 6-9%
characteristics and do not blister as much on baking sterols. The rapid increased consumption indicates it
as many vegetable oils. The refined oil has a large is finding a place in modern industrial protective
part of the saturated f a t t y acids removed. The iodine coating manufacture. The refined tall oil esterified
nmnber of the individual unsaturated f a t t y acid radi- with glycerol or pentaerythritol produced a product
cals in fish oil range from 75 to 360, the average which is roughly equivalent to a 12-gallon linseed-
iodine number is 180-190. Refined fish oil does not estergum varnish.
break. Although its use i n paints has not become general
Processing above 590~ causes a rapid increase in and it is considered a low cost diluent, yet tall oil is a
acidity. It has been found a temperature of 560~ monument to the ingenuity, imagination, persever-
is commonly used to process fish oil in saturating the ance, and ability of modern science to convert a by-
highly unsaturated components without affecting ma- product into a valuable adjunct of modern protective
terially the lower unsaturates. coatings. Tall oil films d r y in a reasonable time to a
Sardine oil which has been bodied to 9 poise at hard tack, free film in paints, At present its use is
535~ and then f u r t h e r bodied to a viscosity of 9S most in the more inexpensive paints. The steadily
to 148 poise b y air blowing, when cut back with thin- increasing supply, at the present time, is being ab-
ner, retains the improved flow, brushing, and levelling sorbed by the linoleum, paint, varnish, soap, lubri-
qualities of oxidized oils. cant, and allied industries.
Fish oils are generally used in oil blends with It is esterified with polyhydrie alcohols. The prod-
perilla and linseed oil. The fish oil films are slow ucts are used in rust-proofing, water-proofing, coat-
drying, have after-tack especially at high humidities, ings for casks, floors, furniture, and similar applica-
poor strength, and a characteristic odor. It is used tions. The esterified tall oil products are darker than
b y some manufacturers as part of a cheap paint the corresponding linseed oil products, slower drying,
vehicle. Raw fish oils have been used in high tem- and less elastic. The same may be said of similar tung
perature baking Japans, barn paints, house paint, oil and oiticica oil products. The weather resistance
fence paint, railroad box ear paint, anti-rust paint, of tall oil is improved on blending with tung oil,
aluminum paint, industrial and maintenance paints, estergum, copal ester, and some synthetic resins. It
structural paint, enamel vehicles, semi-gloss paints, makes a good component in short oil varnish.
fattening lacquers, and primers for wood surfaces.
Fish oil is used in short, medium, and long oil var- Other Oils
nishes of the phenolic type, synthetic varnish type, There are a large number of other oils which have
and all oil varnish types. The oil may be added di- been investigated. Some have been used in a limited
rectly in first cook, check, or cut baek. amount in special formulations. Most of these oils
Fish oil and linseed oil blends used in house paint have one or more defects, when compared with the
vehicles show less dirt pickup than pure fish oil ve- major drying oils, the chief of which is unavailability.
hicles. Fish oil may be blended with tung, linseed, The more important of these oils are Po-yoak oil,
oitieica, perilla, or soybean oils. Care must be exer- poppy seed oil, chin oil, stillingia oil, sunflower oil,
cised to formulate correctly to reduce after-tack and safflower oil, hempseed oil, walnut oil, corn oil, rape
undesirable soft film properties. Fish-tung oil blends seed oil, sesame oil, cashew nutshell oil (liquid),
are used in smoke stack paints that will withstand bonito oil, lumbang oil, nigerseed oil, grapeseed oil,
heat and light. milkweed seed oit, and m a n y others. The fact that
Fish oils are used in caulking compounds because these oils may be more or less scarce at this time has
of surface d r y and flexible interior, and freedom from not hindered the continued investigation of their
bleeding, staining, shrinkage, and sagging. I t is also properties. Many of these oils, like safflower oil, will
used in roof paints and rough lumber paints. in time be recognized f o r some particular properties
In short oil varnishes the addition of fish oil im- which will stimulate their production.
proves the elasticity and color, lessens skinning, and Hempseed oil dries more slowly than linseed oil,
increases compatibility with pigments. The addition b u t there are no yellowing tendencies on storage. The
of fish oil to medium oil length cooks of varnish helps oil fihn in outside house paint has low water absorp-
to insure gas-proofing and helps in the dispersion of tion and hence low film emulsification tendencies. Its
the polymers, thus reducing skinning and gel tend- durability is as good as linseed oil in outside house
cncies and decreasing the reactivity with basic paint. It dries in a way similar to poppy seed oil but
pigments. more slowly than linseed oil. Boiled four hours, the
The long oil varnishes, such as mixing varnishes, drying time is the same as linseed oil similarly
spar varnishes, finishing varnishes, railroad varnishes, treated. Because of its low staining power it makes
enamel varnish vehicles, and industrial paints, all an excellent grinding vehicle for colors in oil. It has
have good waterproofness and good exterior proper- higher dispersing power than linseed oil. The faint
ties. IndustriaI liquids and mixing vehicles incor- bluish color of the oil is an asset in grinding white
porate refined o r bodied fish oil to reduce cost and pigments. I t may be used to cook Congo resin var-
meet certain specific industrial requirements as rail- nishes and alkyd resins. I t is blended with linseed
road paint and pipe coating paints. Lightly kettled or perilla oil for outside house paint vehicles.
 THE JOURNAL OF THE AMERICAN OIL CIt/~MISTS'SOCIETY, NOVEMBER,1950 521

Sunflower oil, a semi-drying oil, yellows less than The drying characteristics are regarded as being
linseed oil, but it dries softer and more slowly. Its between that of non-drying and semi-drying Mass of
use in varnish oil at present is limited by its darken- oils. It has been used in alkyd resins.
ing characteristics. It dries more slowly than soybean Sesame oil is a member of the semi-drying oil class.
oil. It may be blended with high iodine number lin- The refined oil may be blended with perilla oil or
seed oil and perilla oil for use in outside house paints. linseed oil to produce outside house paint vehicles,
It makes good alkyd resin solutions and can be used providing not too much sesame oil is used to render
in varnish in conjunction with drying oils, the dried film soft. I t has been used in alkyd resins,
Raw chin oil drys slowly and because of its high linoleum, and soap.
surface tension collects in drops. The tendency to Cashew nutshell oil is a by-product of the cashew
form drops may be eliminated if it is heated to 410~ nut industry. It is not a triglyceride as are the other
for 15 minutes. In drying it is superior to linseed oil natural oils discussed but is considered to be a modi-
treated with the same amount of drier. There is fled phenolic liquid resin. The reduced cashew nut-
little change in color after heat bodying hence it is shell oil is used in the formulation of cement paints,
used in light colored varnishes or alkyd resin. I f the industrial paints, mariue paints, and chemical re-
supply is developed, it may be used in exterior paints sistant paints. It makes a good plasticizing oil.
and enamels. Blends with vegetable oils are used in floor varnish
The poppyseed oil dates from the time of Diosco- where it is reported to improve toughness, flexibility,
rides and was used before linseed oil was known. and waterproofness to the dried film. I t is used as a
Poppyseed oil might be substituted for soybean oil solvent for pitches, asphalts, and resins. It polymer-
if it were more plentiful. It has been used since the izes when heated and has been used to reduce the
17th century by Dutch artists who appreciated its baking temperature of baking enamels. It is used in
slow drying properties, but painters p r e f e r r e d linseed formulations with many synthetic resins, natural
oil. The oil tends to retain its color with age and re- resins, aldehydes, Mkaline earth oxides, and hydrox-
quires more drier than linseed oil. The oil film tends ides, polyhydric alcohols, alcohols, and some amines
to show cracking if the pigments are too finely to form valuable products. Sulfuric acid causes
ground. Poppyseed oil films dry softer and more cashew nutshell oil to polymerize to a resin of ex-
slowly than linseed oil. ceptional toughness and resistance to wear, abrasion,
Oxidized poppyseed oil is more soluble in solvents and high temperature.
than linseed oil. Poppyseed oil does not have the Stillingia oil resembles linseed oil in its chemical
keeping properties of linseed oil. Glycerides of poppy- and physical properties. It should be classed as a dry-
seed oil are easily hydrolyzed, and the acid value of ing oil, but since the supply is searce on account of
the oil increases on exposure. Thickened poppyseed lack of interest in the cultivation of the stillingia tree
oil has a reduced drying time and the films show little and the difficulty in harvesting and separation of the
tendency to crack. Because of supply it cannot com- oil from other undesirable f a t t y and waxy products,
pete in house paint with linseed or similar oils. it is discussed in this section of the paper. It can be
Cottonseed oil without modification has little use in substituted for linseed oil in paints, varnishes, and
paints. It dries more slowly than soybean oil and
alkyd resins.
remains soft for long periods of time; the films pick
up dirt. Its use in the manufacture of alkyds resin W a l n u t oil is similar to hempseed oil in many of
has proven to be of considerable value. It can be used its properties and dries like soybean oil. Hot pressed
as a plasticizer, also in varnish with other oils. w a h m t oil has been used in paints and artists' colors
Corn oil is a member of the semi-drying oil class. from early times. I t reacts with styrene in the pres-
Its drying characteristics lie between soybean oil and ence of a catalyst to produce excellent styrenated oils.
cotton seed oil. The refined oil may be water-white It has been used in varnish and alkyd resin. Its use
in color. It has been used in blends with tung oil and would become general if an adequate supply were
linseed oil up to 10% of the total oil content for a available at a price less than that of linseed oil.
vehicle in ready-mixed paints to help prevent hard Safflower oil has been used as an edible oil like
settling. Corn oil in some localities is used in oil m a n y of the other semi-drying oils for centuries. Not
blends to produce vehicles for barn and outside house until recent years has it been considered seriously as
paints, where the corn oil content should be kept low a protective coating vehicle in the United States. Tbe
to prevent soft drying. Blended with linseed oil it major portion of the f a t t y acids found in safflower oil
has found favor as a non-skinning, grinding vehicle is linoleic acid ; there is less than 1% of linolenic. The
for paste colors. The oil does not gelatinize on heat- raw oil dries better than soybean oil. There is no
ing. It would be used more in alkyd resins if the after-yellowing in the dried film, even under extreme
supply could be increased. Corn oil is used in the exposure conditions. The oil is easily bleached to a
manufacture of linoleum, oil cloth, and varnish. water-white color which is equivalent in color to
Stand oil prepared from corn oil is a component of highly refined corn oil. I t has been stored eight years
good drying enamels, which do not yellow as much as without any noticeable effect on its clarity, color,
similar enamels that contain linseed or tung oil. luster, or acidity. The oil solidifies at 8~ but re-
Ravison oil of good quality may be difficult to pro- mains clear.
cure since its properties are greatly influenced b y the Boiled oil and stand oil prepared from safflower oil
growing environment and cultivation techniques. The show better properties than the raw oil. It is less
oil of commerce varies from yellow to a dark brown. durable than linseed oil and may be used in place of
The high percentage of isolated double bond f a t t y poppyseed oil in artists' colors. The oil does not
acids, 70-80%, has limited the commercial application break when heated to 600~ or discolor. Heated to
of the raw and blown oil to the roll of plasticizers in 600~ for 2.5 hours, the oil: suddenly gels, but the
nitrocellulose lacquers or similar types of application. gel, unlike tung oil gel, is soluble in turpentine and
522 THE JOURNAL OF T H E AMERICAN OIL CHEMISTS' SOCIETY, NOVEMBER, 1950

many other organic solvents. The acid number is 3, Bearn, J. G., "Tim Chemistry of Paints, Pigments a n d V a r n i s h e s , "
Ernst Bonn Ltd. ( 1 9 2 3 ) .
lower than most vegetable oils similarly treated: 4. Blom, A. V. " O r g a n i c Coatings in Theory and Practice," Elsevier
Publishing Company, New Y o r k (1949).
Safflower oil is used successfully in house paints, 5. Chatfield, H . W., " V a r n i s h Constituents," Interscicnco Publishers
especially if blended with tung oil, linseed oil, or Inc., New York ( 1 9 4 4 ) .
6. Heston, Noel, "Outlines of P a i n t Technology," 3rd Edition;
perilla oil. It has been used to make styrenated oils. Charles Griffin and Company, Ltd., L o n d o n ( 1 9 4 7 ) .
7. I~Iilditch, T. P., " T h e Industrial Chemistry of Oils, Bats, and
Boiled oil and bodied oils are non-breakable and are Waxes," J o h n Wiley and Sons Inc., New York ( 1 9 4 1 ) .
used to produce varnishes with synthetic and natural 8. Huff, Ralph H., Scientific Methods of Varnish Manufacture,
American Paint Journal Company, St. Louis, Me. ( 1 9 4 6 ) .
resins. Raw or bodied safflower oil makes good alkyd 9. Jamieson, G. S., "Vegetable Fats and Oils," 2 n d Edition, Rein-
hold P u b l i s h i n g Corporation, New York ( 1 9 4 4 ) .
resins. As production increases, safflower oil will 10. Joachin, Benjamin, "Applied P a i n t and Varnish Chemistry,"
become more popular among protective coating Vol. I, Pigments and Oils; American Paint Journal Company, St. Louis,
Me. ( 1 9 3 4 ) .
formulators. 11. Kirsehenbauer, I-I. G., 'Tats and Oils," Reinhold Publishing
Corporation, New York (1944).
Future of Synthetic 0ils 12. Lewkowitsch, J., "Chemical Technology of Oils, Fats, and
Waxes," Vol. I I a n d I I I , Macmillan and Company, London ( 1 9 2 3 ) .
Now that we have considered the use of the more im- 13. Martin, R., "Lacquer and Synthetic Enamel Finishes," V a n
Nostrand Company, New York ( 1 9 4 6 ) .
portant vegetable oils in paint, just a word in regard 14. Mattiello, J. J., "Protective and Decorative Coatings," VoL I
to the future. There are numerous patents and appli- and I I I . , J o h n Wiley and Sons Inc., Now York ( 1 9 4 7 ) .
15. Morrell, 1~. S., and Wood, I-I. R., Chemistry of D r y i n g Oils,
cations for patents directed toward the production of Van Nostrand and Company, New York ( 1 9 2 5 ) .
16. U. S. D e p a r t m e n t of Agriculture, " T h e Fats and Oils Situation,"
synthesized oils from non-fatty acid raw materials. July 1947 and ( 1 9 4 9 ) .
To date in spite of the tremendous amount of time, 17. Von Fischer, Carl, " P a i n t and Varnish Technology," Reinhold
P u b l i s h i n g Corporation, ( 1 9 4 9 ) ,
expense, and talent being directed toward the de- 18. Wampler, R. I~I., "Modern O r g a n i c Finishes," Chemical Pub-
lishing Company Inc., Brooklyn ( 1 9 4 6 ) .
velopment of a suitable replacement material for the
fatty acids in drying oils, the ideal solution is not in II. TECH,'~I~AL .~ND ~V~D~ JOURNALS
sight. If and when the new process is developed, the 1. Beavers, E. M., "Alkyd Resin Technology," Am. P a i n t Journal,
vegetable oil industry will face stiff competition, pro- 33, April 11, 1949.
2. Bradley, T. F., and Richardson, D., Ind. E n g . Chem., 34, 237
vided it is plentiful, cheap, free from seasonal flluctu- (1942).
ation, and independent of climatic variations. At 3. Bolley, D. S., Ind. Eng. Chem., 41, 287 ( 1 9 4 9 ) .
4. Burrell, H., Official Digest, F. of P. & V. Prod. Clubs, p. 326,
the present stage of synthetic oil development the April 1948.
5. Chatfield, H. W., P a i n t X I X (4), 115 ( 1 9 4 9 ) .
score is in favor of the natural oils as slow-drying, 6. Christensen, L. M., Am. P a i n t J o u r n a l , 34, (20), 54 (1950).
yellowing, and severe checking on aging are the 7. Cosgrove, C., and Earhart, K. A., I n d . & E n g . Chem., 41, 1942
(1949).
hurdles which continue to present problems that must 8. Eisenschiml, 0., Am, P a i n t J o a r n a l , 32, 72 ( 1 9 4 7 ) .
be surmounted. 9. Falke~hurg, L. B., e t a l , I n d . E n g . Chem., 38, 1002 ( 1 9 4 6 ) .
10. Greaves, J. H., Paint, X I X , I I I ( 1 9 4 9 ) .
There are many claimants for the vegetable oil 11. ttafeli, J. M., By Gum, Aug.-Sept., p. 7 ( 1 9 4 8 ) .
12. H a r d y , E., P a i n t X I X , 32 ( 1 9 4 9 ) .
"oscar" in protective coatings. Styrenated petroleum 13. ISilditch, D., P a i n t , X I X , 126 (1949).
products of butadiene, acryleates, vinyls, acetylates, 14. ttovey, A., Official Digest, p. 697 ( 1 9 4 9 ) .
15. Ivanova, A. A., Bespalko, I. A., P a i n t X I X , 118 (1949).
rubber polymers, halogenated aliphatic and aromatic 16. Kienle, R. H., Official Digest of F. of P. & V. Prod. Clubs, 11,
January (1950).
organic compounds are among those which have been 17. Konen, J. C., Official Digest, F. of P. & V. Clubs, p. 647 ( 1 9 4 8 ) .
suggested and introduced to the market but have 18. Larson, L. P., and Calbock, J. ~I., P a i n t 0il and Chem. Rev.,
112, 25 ( 1 9 4 9 ) .
found only limited application in specialties. Vege- ] 9 . Lanson, I~I. J., et al., Ind. Eng. Chem., 37, 179 ( 1 9 4 5 ) .
20. Lewis, A. J., P a i n t Ind. Magazine, 64, 198 ( 1 9 4 9 ) .
table oil scientists are not asleep. They know they 21. Long, J. S., Official Digest, F. of P. & V. Pred. Clubs, Sept.
have a valuable and abundant raw material supply 1949.
22. Lovcrn, J. A,, P a i n t Ind. Mug., Aug., p. 224 ( 1 9 4 9 ) .
and are releasing methods for temperature treatment 23. Mann, L. C., Am. P a i n t J o u r n a l 33, 66 ( 1 9 4 8 ) .
24. Menaker, A. J., P a i n t Oil & Chem. Rev., 113, 36 ( 1 9 5 0 ) .
of semi-drying oils like grapeseed, rapeseed, and to- 25. Miller, N. Y., J. of Phy. Chem., 50, (4), ( 1 9 4 6 ) .
matoseed oils to convert them into materials which 26. Northwestern Club, Official Digest, F. of P. & V~ Prod. Clubs,
p. 298, p. 838 (~949).
have drying properties similar to linseed oil. Syn- 27. Priest, G. W., a n d V. Mikusch, J. D., Ind. Eng. Chem., 32, 1314
(1940).
thetic tung oil produced from fish oil and synthetic 28. Radlove. S. B., e t a l . , Catalytic Conjugation of Linseed and Soy-
linseed oil processed from coal oils are realities. The bean Oils, Northern Regional Research Laboratory, U. S. D. A., Peoria,
II1., October 1945.
continued development of the synthetic oils will be 29. Rauber, E. L., Nat. P a i n t Bull., 10, 3, 5 ( 1 9 4 6 ) .
30. ]~azzano, D. D., Am. P a i n t J o u r n a l , 3~, 29, 1948.
watched and will assume increasing importance as 31. Reizenstein, L. J., Drugs, Oil, a n d Paints, 53, 212 ( 1 9 3 8 ) .
commercial competitors of vegetable oils. 32. l~eutenauer and Sisley, O. A. 45, 8492 ( 1 9 4 8 ) .
33. Rice, I/. L., P a i n t and Varnish P r o d . 1 2 (Feb. 1 9 5 0 ) .
A n y changes from vegetable oils to synthetic oils 34. Rice, I~I. L., P a i n t and Varnish Prod. 8 (Nov. 1949).
will be slow as manufacturers are loath to change 35. Schwitzer, M. K., P a i n t Mft. 18, p. 159 a n d 168 ( 1 9 4 8 ) .
36. S c h w a r c m a n , A., Official Digest, F. of P. & V. Prod. Clubs , p.
fronl an established product, even though the new 325, (Apr. 1 9 4 8 ) .
37. Stieg, F. B., Official Digest, F'. of P. & V. Clubs, p. 94 (Feb.
product may be superior, until it has been established 1950).
beyond any reasonable doubt that they can depend 38. Scofield, F., Official Digest F. of P. & V. Prod. Clubs, p. 438
(1948).
upon an adequate, stable, available, and steady-priced 39. Sutheim, G. M., Chem. Industries, 62, 65, a n d 241 ( 1 9 4 8 ) .
40. Terrill, 1~. L., and Mitchell, F., Am. P a i n t J o u r n a l , 3~, 94
material for their production schedule. (1947).
41. Touchin, ~I. R., P a i n t Mfg., 16, 186 ( 1 9 4 6 ) .
REFERENCES 42. Wochholtz, W. A., Official Digest, F. of P. & V. Prod. Clubs,
p. 446, ( J u n e 1948).
I. BOOKS
III. MISCELLAI~EOUS
1. Bailey, A. E., "Industrial Fats and Waxes," Interscience Pub-
lishers Inc. (1945). Nat. Paint, Varnish and Lacquer Association, Scientific Section
2. Bartcll, F. E., Laboratory Manual, "Colloid Chemistry," Edwards Circulars, Nos: 571, 582, 622, 651, 654, 656, 662, 669, 672, 673,
Press, Ann Arbor, Mich. (1947). 697, 721, 725.