LESSON 1

ORGANIC COATINGS

PART 1 ~ INTRODUCTION TO COATINGS

PART 2 ~ GLOSSARY OF COMMON TERMS

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PART 1 ~ INTRODUCTION TO COATINGS

The three volume set of student textbooks was created with three aims in mind.
1) To help individuals to increase their ability to apply themselves more effectively in the coatings
and related industries.
2) To help persons already in the coatings and related industries to more fully understand the
basic and recent advances in the coatings technology, and
3) To be a handy reference guide for each student

Each of the three books covers a segment of the coatings technology dealing first with Coatings Raw
Materials in Book I, Architectural in Book II, and Industrial Coatings in Book III. The reasoning behind
this division of the material is that for the students to be able to formulate coatings he/she must first
be familiar with all the main raw materials groups use din the process of formulating the various types
of coatings which are discussed I the second and third volumes.
In addition to the coverage of the individual raw materials their chemistry properties and selection, an
introduction lesson on Basic Organic Chemistry will provide short review of the most important
chemical reactions by which many of the products are created. Books and articles pertaining to the
individual lessons are listed at the end of each lesson. These should be consulted for further study.

Historical Background
Paint is almost as old as man himself. Over 35,000 years ago, people living in caves decorated the walls
with paints and of naturally occurring materials such as clay, chalk and animal fasts. There essential
components have not changed over these thousands of years.
What did change since the early times, and what has caused these improvements? The answers lie in
the ingredients, in the method of manufacturing, and in the method of application. The progress
continues from the early cavemen to the early civilization of Egypt, Greece and Rome (3000 – 600 B.C.),
to the artists and craftsmen of the Middle Ages (400 – 1600 A.D.), the Renaissance and on to the
Industrial Revolution that took place from 1600 to 1900 and then to the present day.
In the early times, and up to the beginning of the Industrial Revolution, the
user of paint was also the paint maker. Paint and the concept of paint
making changed very slowly until almost the 18th century. Demands for
paints of all types had increased to such an extent that it became worthwhile
and profitable for people to go into business to make paints and varnishes
for others to use.
In the 1800’s paint production began because the industrial revolution was changing and the end use
for paint. Iron and steel had to be protected from rust, for which lead and zinc based paints were
developed. Science was also slowly awakening with new pigments, like Prussian Blue (in 1704). In 1740
turpentine was discovered. Formaldehyde chemistry was discovered in 1850, and nitrocellulose in
1870.
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In spite of the new discoveries in chemistry, the art of paint formulating still remained relatively static
until the 1900’s. In the early 1900’s recipes were varied between natural resins and oils and the many
dyes and pigments, but one method of application was common – “the brush”. Paint usually took hours
or days to dry.
Before the First World War (1914 – 1918) cars, for example, required twelve
coats of paint, applied by brush, and each coat was dried 24 hours. This was
accelerated the exploitation of the discoveries of chemistry and the growth
of the chemical industry.
New colored pigments and dyestuffs became available. Resin chemistry
advanced with such products as phenol formaldehyde resins, melamine resins,
alkyd resins and acrylic resins, to name a few. Drying oils live on in modern
coating chemistry, but now as modifiers to alkyds, urethanes and other resins.
When we look back on some of our paint history, we see that the earliest known paints were limited in
color, they were not durable to outside exposure, and were very crudely applied. In other words, they
were suitable for interior decoration and not protective in nature.
Progress in paint formulating and manufacturing have varied at different rates over the years.
Sometimes the progress seemed to standstill, and at other times it seemed very fast. As the choice of
pigments widened, the newer resins were discovered, the quality and durability improved. Paint
making thus became a job and skill in itself.
The methods of science have ensured that the quality of paints or coatings can be controlled and
reproduced again and again. The demand for new products, new building materials are with us, and
paint making has become a “Technology”, growing to meet the durability and protection required.
Should one wish to read more on paint history, two books are recommended. Technology of Paints,
Varnishes and Lacquers, by Martens, and Surface Coatings – Volume 1, prepared by the Oil and Color
Chemists Association of Australia.
The Coatings Industry is important to the economies of most developed countries. Industries use many
types of paints (cars, machinery, marine etc), and the home owner needs decorative and protective
paints. The coatings industry products are split roughly into two major categories. Architectural or
Decorative paints and Industrial coatings. The architectural market is moving more and more to water
based stems (latex paints). The other segment, the industrial market, are coatings formulated to meet
special conditions that are required for automobiles, trucks, marine ships, aircraft and a wide variety of
other consumer items.
Ever since the Second World War (1939 – 1945), changes in coatings
technology have been rapid and have kept pace with the many other
sciences. As with mentioned earlier, we have advanced into an era of
synthesis) pigments, resins, additives and solvents), and although we
still rely to some extent on the natural products, the shift is definitely
to the tailored made synthetics. The synthetic pigment, resin and
additive chemistries has allowed the industry to meet the
environmental requirements, government regulations, and even to
learn how to control out waste management.
We are noticing that the “non-productive” activities connected with government compliance and
regulations is having an effect on manufacturing operations, the type of raw materials we ca use, and
also on the methods of application. The coatings industry is positive in its approach and is responding
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to the new demands with the help of the many raw materials suppliers. The problems are not going to
get easier as time goes by, and many will become even more complex.
The coatings industry will be able to meet the emerging demands of our complex society. This will have
to be an industry that will put aside our individual demands and work as a team to insure our future. By
constant educational training, and the proper dissemination of new technical or scientific information,
we will progress in a positive manner to meet the environmental challenge.

What Does Paint Consist of?

Much depends on the end use and although some are as simple as whitewash, most coatings are
extremely complex. The constituents of all paints can be summed up by the diagram at the top of the
next page.

Paint

Pigment Vehicle Additives

Binder Solvent (or diluent)

This coating, or paint, decorates and protects surfaces. The pigment is to decorate (add color or hide
the unsightly substrate), and provide protection, and in some cases functional value. The resin or
vehicle binds the pigment together, acts as the glue to hold the coating to the substrate, and provides
protective qualities. The solvent helps to make the coating application easier and the additives give
certain features to the paint performance.

The most important features of paint are:

1) the east with which it is applied
2) the speed of drying
3) the adhesion to the surface
4) and the strength and durability of the dry film

CLASSIFICATION OF COATINGS
Classification by Function
Organic coatings are applied for purposes of protection and decoration. Long-term protection of steel
and aluminum against corrosion, protection of wood against decay and disintegration, and protection
of food products by coated film packaging materials are common examples of the protective function
of organic coatings. Decorative coatings are commonly used to satisfy aesthetic requirements of
appearance, to provide color, glass and other optical effects.

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Outside the field of protection and decoration, organic coatings are applied for imparting
soundproofing, fire retardance, abrasion resistance, low friction coefficient, magnetic memory storage,
electrical conductivity and electrical insulation, etc.

Classification by Chemical Type

Inorganic Coatings
(a) Metallic
Metals are coated on other metals and plastics by a variety of processes but mainly by
electrochemical reduction process. Copper, nickel, cadmium, and chromium coatings for
protection and decoration of steel are usually electroplated. Zinc is often electroplated on steel,
but is also applied from a melt. Some metals are applied by explosive bonding. Aluminum is
evaporated on plastics for decoration.

(b) Conversion Coatings

Metals, particularly steel, aluminum, and zinc, are often treated with chemicals, chiefly chromic
and phosphoric acid, to clean them and then to deposit adherent, relatively tough, inorganic
oxidation products of the metal.
These deposits are of slight protective value themselves, but they usually produce surfaces to
which organic coatings adhere more readily than they do to untreated metal, and they enhance
the protective value of the subsequent coatings. These are called conversion coatings.
The chemicals dissolve some of the metal and deposit insoluble basic salts and oxides. The
reaction can be performed with chemicals alone, hot or cold, or with the aid of electric
current. Most often, proprietary mixtures of chemicals are used which are claimed to
increase speed or details of effectiveness.

c) Siliceous Coatings
Ceramic coatings are silicate – based products applied from aqueous suspension of oxides and
siliceous materials. On drying of the water a porous powder results which is melted and cooled
to a gloss. The coatings require high temperatures for application and are brittle in service.
Although they tend to have excellent protective qualities when undamaged, they are easily
damaged mechanically, and can be repaired only with difficulty. Their decorative quality is
relatively limited.
Ceramic deposits are also applied as rough, discontinuous coatings on aluminum pots and pans
before the deposit of polytetrafluoroethylene finish. The ceramic deposits improve the
perceived resistance of the polytetrafluoroethylene to damage by scratching. In such cases,
because the ceramics are discontinuous, the metal can be formed, even after the ceramics
have been fused and cooled, without substantial damage.
Related to the ceramic coatings are coatings based on silicate solutions which are hardened and
made insoluble by the action of acids. Most prominent are zinc – rich coatings containing
sufficient metallic zinc power to make the coatings electrically conductive.

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 Applied to steel, they are hard, chemically resistant, the protective to the steel surface much as
a galvanized steel coating. Of lesser importance are other inorganic coatings like whitewash
(lime) or Portland – cement finishes applied from water.

Organic Coatings
(a) Definitions, Binder Pigment, Vehicle
Organic coatings are usually supplied as liquids which are converted on the substrate to solids.
In order to have the required strength, the solid coating must comprise a continuous phase, the
binder, consisting mainly of large molecules which generally adhere to the substrate, and in
which pigment particles may be dispersed. Organic coatings have organic binders. A pigment is
a finely divided (0.01 – 25 microns) insoluble solid. Pigments provide, among other benefits,
opacity, color, and durability, but they affect the flow properties during application and the
mechanical properties later. Additives are used in minor amounts to provide special functions.
It is important that the organic binder have a high molecular weight in its solid form in order to
provide a strong film. The minimum molecular weight required will vary somewhat with the
chemical characteristics of the binder. Low molecular – weight organic solids are, however,
volatile, fluid or weak. They will either smear or powder easily.
The binder, in some cases, may be of low molecular weight during application, but in those
cases, chemical reactions must be used to raise the molecular weight before the coating is put
to practical use.
The term “vehicle” is applied to the ingredients of the coating before application, exclusive of
pigment.
The vehicle will include solvents, water, organic polymers (either in high molecular weight form
or in the temporary low molecular weight form), and various additives which remain dissolved
or dispersed in the binder. Occasionally, organic coatings are applied in powder form. In such
cases they are melted to a flowable liquid form before solidification. If the binder is of low
molecular weight in the powder form, it must be converted to the high molecular weight after
application.

(b) Sales Classifications

Architectural Coatings – These are usually liquid coating compositions marketed to relatively
unskilled users through paint dealers, hardware stores, and department stores. They are
usually formulated to be applied with simple techniques – brushes, rollers, or aerosol bomb
containers and to require no ovens or other machinery for converting a liquid film to a solid one
or for dealing with solvent vapors.
Industrial Coatings - These are usually sold to factories where specialized application and drying
equipment can be justified economically.

(c) Classification by Chemical Reactivity

Non-Reactive – The binder usually solidifies as the solvent or water evaporates, and no further
reaction is necessary to achieve strength or adhesion. Molecular weight of the binder is usually
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 greater than 50,000. Nitro-cellulose, polyvinyl acetate, polymethyl methacrylate are examples
of such binders, and the coatings of such binders are called lacquers.
Reactive – The binder consists of small molecules (molecular wt. <10,000) which react after
application to yield the large molecules required for strength and other properties. The
coatings comprising these binders are called enamels. (The term enamel is also used to
describe any hard glossy coating. Usually the context will help one to understand the meaning).

(d) By State of Dispersion of the Binder Before Application

Solution – Sometimes the binder is molecularly dispersed as a solution in a suitable solvent or
water.
Particular Suspension – The binder is in the form of polymer particles dispersed in water or an
organic solvent. Each polymer particle may contain many molecules. In latex paints the binder
is largely in the form of an aqueous dispersion. As a special case, the binder of the newer power
finishes can be considered as dispersions of polymer in air.
Dispersions of particulate polyvinyl chloride mixtures on organic solvents and plasticizers are
useful for coating cloth. Dispersions comprising of methyl methacrylate polymer in solvents are
useful in painting of automobiles.

GENERAL DEFINITIONS
WHAT IS PAINT? - A dispersion of pigment in:
a) A vehicle and solvent, or
b) An emulsified vehicle

When cast in some manner such as brushing, roller, or spray and the solvent or volatile portion
evaporates, a continuous film is developed by oxidation, evaporation, catalyzation or other means that
is decorative and protective.

Paint Type Definition

Vehicle Film former – in solution or emulsion form. Imparts characteristics of toughness,
durability, dry time, etc (Alkyds, oils, latex emulsions)

Pigment Powdery materials that impart hiding and color to the paint.
For example TiO2, Yellow Oxide, Lamp black, etc.)

Extender Pigments Also powdery materials but do not impact, hide or color. They are used to control
gloss and primarily to reduce cost. Materials such as clay, talc, calcium carbonates,
magnesium silicates, silica and diatomaceous earth.
Additives
Used to prevent settling of pigments as Bentones or Aluminum Stearate.
Suspending Agents

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 Used in alkyds and oils to make them dry faster e.g. cobalt, calcium, magnesium,
Driers rare earth, naphtanate.

Anti - Skinning Used in oils and alkyds to prevent surface skinning in containers (ASA).
Agents
Used in all kinds of paints to promote pigment wetting ease of grinding, suspension,
Wetting Agents stabilization.

Anti - Foaming Used in primarily in water paint systems to minimize foaming and air entrapment.
Agents
Used in emulsion systems to insure proper coalescing of the latex particles upon
Coalescing Agents drying.

Used in water paints to increase viscosity of paints to application viscosity. Materials

Thickeners such as Cellulosics (water soluble polymers), Natrosol, Cellosize, Methocel, and the
newer associative thickeners.
Viscosity Control Small amounts used in alkyd and oil type paints to increase viscosity.
Agents
Various additives are available for both solvent and water systems that contribute
Other additives various properties such as non-sagging, mar resistance, freeze/ thaw, wet edge, etc.

Solvents
Used to dissolve the vehicles and make them into a usable liquid form. Choice of solvents with varying
evaporation rates can change the drying characteristics of the paint.

Choice of solvents with varying solvent strength can change the viscosity of the paint. M.S. V.M.&P, Toluol,
Xylol, MIBK, Cellosolve, etc.).
Water

Used as a carrier (solvent) for the latex in emulsion systems and as a solvent for certain resins in water
soluble systems.

Bibliography:
Alan Brandau – Federation Series on Coatings Technology, “Introduction to Coatings Technology” FSCT
Blue Bell, PA, USA.
Oil & Colour Chemists’ Association, Australia, “Surface Coatings, Vol. 1, Raw Materials and Their Usage”

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PART 2 ~ GLOSSARY OF COMMON TERMS

Term Definition Structure

Absorption The penetration of one substance into another. The surface of a material
is recognized as having considerable absorption when it takes into itself,
and holds, the finishing materials applied over it. Usually, the more
porous the surface is, the greater is the degree of absorption.
Acidic A water solution that contains a greater than normal concentration of
hydrogen ions. The pH would be less than 7. Also, associated with this
would be neutral pH of 7 and alkaline pH of 7+.
Acid Value or Number This number is often referred to in resin data sheets, in oils and
varnishes. It is the number of milligrams of KOH (potassium hydroxide)
required to neutralize the free acid in one gram of oil, resin, varnish or
other substance. The results generally reported on the nonvolatile
portion.
Acetate It is an ester of acetic acid. O
ll
CH3 – C – O - R
Acrylate An ester of acrylic acid with the general O
structure.
ll
CH2 = CH – C – O – R
The base chemical acrylic
acid has the following
structure:
O
ll
CH2 = CH – C - OH
The COOH is the functional
carboxyl group.
Accelerated Aging The chemist attempts to design tests and experiments to speed up the
process of obtaining aged results. Accelerated aging is then any set of
conditions designed to produce in a shorter time the results obtained
under normal aging conditions. The usual factors considered are heat,
light and oxygen either separately or combined. In the case of latex paint
accelerated aging usually is done in a half pint can at 50°C (122°F) for a
specific period of time (e.g. one week, two weeks, three weeks etc.)
Accelerated Testing These are tests, the conditions of which simulate those encountered in
practice, but which have been accentuated artificially to provide
performance results in shorter period of time. Coatings do not
necessarily behave under such tests exactly as they will under actual
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 conditions, but any coating which gives good performance under
accelerated tests may be shown to have possibilities which are worthy of
further consideration and experiments.
Accelerated These are tests to simulate, but at the same time intensify and
Weathering accelerate, destructive action of natural outdoor weathering.

The tests involve exposure to artificially produced components of natural

weather, light, heat, cold, water vapor, rain (and in some cases air
pollutants) which are arranged and repeated in a given cycle. The tests
are varied and no universally accepted tests are used throughout the
industry.
Alcohol Any of the class of the chemicals compounds which has the generic
formula ROH. The OH is called a hydroxyl group and R represents an alkyl
group. Examples are:
Alcoholysis It is the general chemical reaction involving O
an ester exchange, the type common to ll
making alkyds. This is a cleavage of a C-C R–C–O–R
bond by the addition of an alcohol. General
structure of an ester is: and the functional group is:
O
ll
–C–O–

Aldehydes The broad class of organic compounds having O

the general formula: ll
R–C–H
and the functional group is:
O
ll
–C–O
The C=O is referred to as a
carbonyl group

Alligatoring A type of paint failure in which cracks form on the surface layer only. It is
caused by the application of thick films which the underlying surface
remains relatively soft.
Anti-blocking An additive used to prevent the undesirable adhesion between touching
layers of Agent coated material such as occurs under moderate pressure
(and sometimes heat and pressure) during storage, manufacture or use.
Anti-oxidant A compound that prevents oxygen from reacting with other compounds
which are susceptible to oxidation. They are often themselves oxidized in
the process of protecting the other compounds. Anti-oxidants are used
to prevent skinning in the containers of solvent based paints.
Architectural These are coatings intended for on-site application to interior or exterior
surfaces of residential, commercial, institutional or industrial buildings,
as opposed to industrial coatings which are coatings applied to factory
made articles, before of after fabrication.

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 Architectural coatings are both protective and decorative, and are
applied at ambient temperatures. Often the term “trade sales paints” is
used and this means exactly the same thing.

Average Molecular It is the molecular weight of a polymeric material determined by the

Weight viscosity of the polymer in solution at a specific temperature. For
example: acrylic are dissolved in a solvent (acetone) and the viscosity of
this solution is compared to the viscosity of acetone, and from this the
molecular weight is calculated. This method gives an average molecular
weight of the molecular chain in the polymer, independent of specific
chain length.
Apparent Density This is the mass per volume of loose, dry pigment (or powder) including
the air voids between the particles. Usually expressed is lb/cubic foot or
grams/cubic centimeter. The Apparent Density is also called “bulk
density”.
Bulking Value This is the reciprocal of apparent density. Solid volume of a unit weight
of materials usually expressed as gallons per pound or litres per kilogram.
Also called specific volume”.
Batch Process Any process in which the charge is added intermittently in definite
portions, or batches, the operations of the process and the removal of
products being completed on each portion before the addition of the
next. This process is opposed to a continuous process. Paints are made in
batch process.
Binder This is a non-volatile portion of the liquid vehicle of a coating. It binds or
cements the pigment particles together and the paint film as a whole to
the substrate to which it is applied.
Biocide It is a chemical agent capable of killing organisms responsible for
microbiological degradation in the container. This is not a fungicide.

Bleeding A condition which exists when the color from a previously painted
surface passes through the new topcoat, producing a stain or
discoloration. This condition is caused by the pigment from the previous
coat being soluble in the vehicle of the top coat.
Blistering It is the formation of dome-shaped projections (large or small) in paint
and varnish films resulting in local loss of adhesion and lifting of the film
from the substrate.
Bloom A haziness which develops on high glass and even semi-gloss surfaces
resulting in the scattering of the surface reflectance. This could be
caused by migration of component such as plasticizer out of the film.
Sometimes there is an undesirable deposit on the surface resulting in the
whitening or loss of gloss.
Brush Drag It is the resistance encountered which applying a coating by brush. This
drag or pulling during application is often due to the viscous nature of
the paint. Sometimes this also is referred to being sticky under the brush.
Chalking The formation of friable powder on the surface of a weathered paint film
caused by the disintegration of the binding medium or the type of
pigment. In modern paints chalking is usually not desirable.

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 Checking The phenomenon manifested in paint films by slight breaks in the films
that do not penetrate to the underlying surface. If the underlying surface
is visible then the break would be called a crack. Checking may be visible
to the naked eye or it may be microscopic and visible only with
magnification of 10x.
Coalescent Or Coalescing Agent is usually a solvent with a high boiling point, which
when added to a coating aids the film formation via temporary
plasticization of the vehicle. The solvent evaporates out of the film with
time.
Color Retention The stability of color after exposure to the elements.

Contrast Ratio It is the ratio of the reflectance of a dry film over a black substrate of 5%
or less reflectance, to the reflectance of the same paint. Equivalently
applied and dried, over a substrate of 80% reflectance (usually a white
surface). The contrast ratio will vary depending on the film thickness and
on the concentration of colorants, the amount of titanium and the P.V.C.
Cracking This is generally described as the splitting of a dry paint or varnish film,
usually as a result of aging.

a) Hardcracking – fine cracks which do not penetrate the top coat,

and occur at random.
b) Checking – fine crack which do not penetrate the top coat and are
distributed over the surface, giving the semblance of a pattern.
c) Cracking – specifically, a breakdown in which cracks penetrate at
least one coat and which may be expected to ultimately result in
complete failure.
d) Crazing – resembles checking, but the cracks are deeper and
broader.
e) Crocodiling or Aligatoring – a drastic type of crazing, producing a
pattern resembling the hide of a crocodile.
Cup/Weight per Gallon Uses a brass or stainless steel cup of exactly 100 ml, and is used to
quickly determine the weight per gallon (or density) of a liquid product.
In the US they use an 83.3 ml cup.
Chemical Reaction Organic chemistry is made up of structures and reactions. A chemical
reaction is the chemical change, which involves the rupture of only the
chemical bonds, which hold molecules together.

We have the C - C, C - O, C - N, C - OH bonds plus many more. All

chemical reactions are in balance or, in other words, the number of
atoms in the reacting substances equals the number of atoms of the
reaction product. Reactions are exothermic when heat is generated and
endothermic when heat is needed to maintain the reaction.
Reactions to Make Reactions to Make Polymers – Only three of the basic type reaction will
Polymers be mentioned here.

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 a) Addition Polymerization – This is the type of reaction where
one molecule is added to itself, or to another type of
molecule. There is NO by product formed. Latex
polymerization is an example.
b) Condensation Polymerization – this is the type where two or
more molecules are reacted to form a new product. There is a by
product formed such as water, alcohol or other similar
substance.
c) Rearrangement Polymerization – A special case of
condensation polymerization, however, no molecules of a by
products are formed.
Other methods of polymerization are ionic polymerization, co-ordination
catalyst polymerization, and group transfer polymerization. Functional
groups play an important part in polymerization.
Delamination The separation of the wood surface at the bonded joints caused by a
cohesive failure in the adhesive, or a failure of the adhesive at the surface.
Separation in the wood, even close to a bonded joint is wood failure. Also
the term applies to failure occurring between successive coatings.
Dilatant Flow A type of flow characterized by an increase in viscosity as shear stress
(Shear Thickening) is increased.

Dispersion Wetting, dispersion, stabilization.

Draw-Down A thin film of even thickness is drawn down by a draw-down bat, or wire
wound rod, at a specific thickness, on a test panel or other substrate.

Drier A chemical compound which accelerates the drying of paint film.

Drying Time The drying of hardening of paint film by stages:

a) Dust Free – the time required for a film to reach a condition
where, if any dirt settles on it, the dirt will not become imbedded,
but may be wiped off after the film has hardened.
b) The time required for a film to reach the condition in which it can
be touched with a light vertical pressure, (no tack left and a finger
print could be left).
c) Hard – the time required for the film to become thoroughly hard
so that any mark left by the thumb, exerting maximum downward
pressure is completely removed by a light polishing with a
soft cloth.
Durability The ability of the material to withstand effects of destructive agents with
which it comes into contact.

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 Efflorescence An encrustation of soluble salts, commonly white, deposited on the
surface of coatings, stone, brick plaster or mortar. It is usually caused by
salts or free alkalis leached from mortar or adjacent concrete as moisture
moves through it.
Eggshell Finish A low sheen (semi-mat) surface which exhibits surface reflectance (Paint)
(gloss) similar to that of an egg shell. The gloss is 20 to 30 as determined
with a 60° gloss meter.
Elongation The increase in length of a material under tension, usually expressed as
percentage of the original length.

Enamel Top coat, which is characterized by its ability to form an especially

smooth film. This term is not limited to high gloss coatings, but may also
include lower degrees of gloss.
Fineness When applied to pigments, it describes the particle size. When applied in
connection with the dispersion of pigments, it means the degree of
dispersion of the pigment agglomerates and is commonly called fineness
of grind or dispersion. A grind gauge (Hegmann) is commonly used to
measure dispersion.
Fish Eyes Paint defect, which manifests itself by the crawling of wet paint into a
recognized pattern resembling small “dimples” or fish eyes”.

Flexibility The degree to which a coating after drying is able to confirm to

movement or deformation of its supporting surface without cracking or
flaking.
Flooding and Floating A concentration on the surface of a paint film of one of the ingredients of
the pigment portion, giving rise to change in color at the surface.
Flooding is a uniform color change at the surface. Floating refers to local
excess of color where one or more of the pigments separates or floats
apart from the others or concentrates in streaks or patches on the
surface of the paint.
Freeze Thaw The extent to which latex paint (water based) retain their original
Resistance properties when subjected to alternate freezing and thawing. Properties
that are check are viscosity, coagulation, lumps formations, specks, color
change and flocculation.
Fungicide A chemical agent which destroys, retards, or prevents the growth of
fungus and spores on the surface of the coating. This is not the same as
“biocide”.
Glass Transition The temperature ranges or region (relatively small) at which there is a
physical change in a polymer from brittle, glossy solid to a pliable
rubbery solid. This is sometimes referred to as the “second order
transition”. The temperature which this phenomenon takes place is the
glass transition temperature (Tg).

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 Gloss Retention The degree to which the original sheen of a coating is retained.

Hiding Power The ability of a coating to hide or obscure the substrate over which it has
been applied uniformly. In number terms it is the number of square feet
over which a gallon of paint can be uniformly spread to produce a
specified contrast ratio. This could also be square meters per liter.
House Paint It is the coating designed for large exterior surface of a building,
generally lower gloss than the coating used for the trim areas. House
paints can be oil base, alkyd, or latex type.
ISO It is the abbreviation for “International Organization for
Standardization”.

Krebs - Stormer It is the most common viscometer used in the paint industry. Paint
Viscometer consistency is measured by its resistance stirring by two-vane paddle,
where the vanes are offset to avoid channeling. Appropriate weights are
added to a platform on a string attached to a pulley, which is connected
to the paddle until a speed of 100 rpm is reached, generally measured by
a stroboscopic timer.
The grams required to reach this speed (100 rpm) are the converted, by
using a conversion table to “Krebs Units” often abbreviated to KU. New
units have new technology but the principle is the same.
Lap As a noun it defines the region where a coat of paint extends over an
adjacent fresh coat. The object of the painter is usually to affect a joint
between the two coats without showing the lap.
As a verb it means to place a one coat of finishing material along-side
another, partly extending over it, causing increased thickness where the
two coats are present.
Leveling It is the measure of the ability of a costing to flow out after application so
as to obliterate any surface irregularities such as brush marks, orange
peel, peaks, or craters which have been produced by the mechanical
process of applying or coating.
Lifting A softening and raising or wrinkling of a previous coat by the application
of an additional coating. It is often caused by solvents.

Lightfastness It is the degree of change or lack of change of color of material exposed

to the same amount and character of light. It is a relative term
dependent on conditions, which must be defined.
Livering The progressive, irreversible increase in consistency of a paint, often
caused by chemical reaction of the vehicle, and the solid dispersed
material. It may also just be a polymerization of the vehicle.
Mandrel Test A test for determining the flexibility and adhesion of surface costing. The
coated materials panel is bent around a conical mandrel or mandrels of
varying sizes.
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 Mar Resistance The ability of a coating to resist damage by light abrasion, impact or
pressure.

Metamerism A phenomenon exhibited by a pair of colors, which match under one or

more sets of conditions, be they real or calculated. Flair or color
constancy is the term applied to the apparent color change exhibited by
a single color when spectral distribution for the light source is changed or
when the angle of illumination or viewing is changed. The degree of
metamerism may be slight or moderate-to-severe and is generally
described by one of a number of type of metamerism (or metameric)
indices.
Migration The movement of certain materials in a coating or plastic the surface or
into an adjacent material.

Mildew Organic surface exposed to moisture are attacked by fungus growth

resulting in discoloration and decomposition of the surface.

Mottle It is the irregular distribution or mixture of colorants or colored

materials, given a more or less distinct appearance of specks, spots or
streaks of color.
Mottling is spotty round marks, appearing as defects in sprayed film of
paint. It could occur due to improper mixing. Mottled is when different
tones and colors are placed next to one another to obtain blotchy or
patchy effects.
Mudcracking It is a paint film defect characterized by a broken network of cracks in the
film.

Microvoids Small voids or holes in a paint medium of such size that when filled with
air (or some other material of different reactive index) they scatter light
much as a pigment does because of the difference in refractive index
between the void and the vehicle. Such air-filled microvoids account for
the white color of snow. Commercial microvoid resins are available and
useful which acts as both vehicle and opacifier in coatings.
Non-volatile The ingredients of a coating composition which, after drying, are matter
left behind on the substrate to which it has been applied. This is the
dried film of paint.
Oil Absorption Quality of oil required (milliliters or grams of acid refined oil) to wet
completely a definite weight (100 grams of pigment) to form a stiff paste
when mechanically mixed. The figure is not absolute, but depends on the
operator as well. It is frequently used as a measure of plastic viscosity.
The test for oil absorption was established when the vast majority of
pigments used in the paint industry were of the inorganic type such as
iron oxides, Titanium dioxides and various extenders.
When testing oil absorption of organic pigments using this method the
results are inconsistent due to the high oil absorption of these pigments
and the related difficulty to wet the pigment properly. For both the
16 | P a g e s 2 0
 inorganic and organic pigments oil absorption as measured by this
method bears little relation to finished mill-ground pigment dispersion.
Oil absorption, therefore, has a meaning of qualitative sort.
Oil Paint 1. This can mean a paint that contains drying oil as the sole film-
forming ingredient.
2. A paint that contains drying oil. Also, an oil varnish or oil-modified
resin like an alkyd resin.
3. Commonly knows as (but technically incorrect), any paint soluble in
organic solvents.
Organic The designation of any chemical compound containing hydrogen and
carbon.

Particle Size The relative percentage of weight or number of each of the different size
Distribution factions of particular matter. This can be a pigment or latex resin.

Peeling The separation of topcoat from previous surface which could be caused
by improper cleaning, preparation or undercoating. May also be a
deterioration of the topcoat because of polymer break-down.
Pencil Hardness A measure of coating hardness based on scratching of the film with
pencil lead of known hardness (e.g. HBB, 2H, 4H etc.). The result is
reported s the hardest lead, which will not scratch or cut through the film
to the substrate.
Pigment Volume The ratio of the volume of total pigment to the volume of non-volatile
Concentration matter (pigment plus vehicle solids) present in the coating. It is
expressed as percentage.
Volume of Pigment
PVC = ______________________________________ x 100
Volume of Pigment + Volume of Solids
Pinholes A pin defect characterized by small pore-like flaws in a coating which
(Pores) extend entirely through the applied film and have the general
appearance of pinpricks when viewed in reflected light. The term is
rather generally applied to holes caused by solvent bubbling, moisture,
other volatile products, or the presence of extraneous particles in the
applied film.
Pre-treatment Usually restricted to mean the chemical treatment of unpainted metal
surface before painting. More common in industrial finishes.

Polymer Substance, the molecules of which consist of one or more structural units
repeated any number of times. Also applied to large molecules produced
by any chemical process. There are different types of polymers:
a) Homopolymer
linear and branched

17 | P a g e s 2 0
 b) Copolymer
random chain
Alternating
Blocked
Oligomer
Branched
cross-linked
Polymers use monomers to make them. Monomers are low molecular
weight molecules capable of reacting with like or unlike molecules to
form the polymer.
Free Radicals in When one considers latex polymerization we have four essential
Polymerization ingredients that are required to form the polymer.
water, monomer(s), surfactants and free-radical
there are other minor ingredients such as defoamers, biocides,
buffers etc., but these are not essential in the process of forming
“radicals”.
radicals are the initiators to get the reaction going and to keep
the reaction going. Radicals are different than conventional
catalysts, because in older to function they decompose. An
example would be where peroxide sulfate breaks down with
heat to form persulfate radicals.
O O O
l l l
O-S–O : O – S – O + heat 2O – S – O
l l l
O O O
Radicals
a) initiates the polymerization
b) propagate the polymerization
c) in some cases help to terminate the reaction
d) chain transfer agents (mercaptan) may also be used with
persulfte to terminate a reaction and thus control the molecular
weight.
Rheology The study of the change in form and flow of matter embracing elasticity,
viscosity, plasticity. It is:
a) A method of paint characterization
b) A window through which other characteristics of a paint may be
observed such as flow, leveling, application, etc.

18 | P a g e s 2 0
 c) Several types of viscosity – Newtonian, non-Newtonian.

Ropy Finish Finish in which brush marks have not flowed out, resulting in a paint
having poor leveling properties. A similar appearance may also be
produced in a paint, which normally has good leveling properties, by
continuing to brush the paint after the film has began to set.
Rocker Hardness An instrument made up of two circular stainless runners connected
Tester through traverse bars spaced 25 mm apart. Rocking frequently is
calibrated by weights on glass standard. It works on the principal that a
“soft” surface dampens the oscillations of a rocking wheel more than a
“hard” one.
Sagging Downward movement of a paint film between the time of application
and setting, resulting in an uneven coating having a thick lower edge.
The sag is usually restricted to a local area, or a vertical surface, and
many have the characteristic appearance of a draped curtain, hence the
synonymous term “curtaining”.
Seeding Formation of small, undesirable particles or granules in paint, varnish or
lacquer.

Self Priming Use of same coating for primer and for subsequent coats. It may be
thinned differently for various coats.

Settling The sinking of prime pigments, extenders or other solid matter in a paint
on standing in a container, with a subsequent accumulation on the
bottom of the can.
Show-through a) Photographing – brush or other irregularities in the previous coat
or substrate that show through the dried top coat.
b) Transparency – the transparency of printed sheets, which
permits printing to be seen from the other side of the sheet.
Shop-coat One or more coats applied in a shop, or plant, prior to shipping to the
site of erection or fabrication, where the field or finishing coat is applied.

Spreading Rate Area covered by a volume of coating material expressed as square feet
per gallon, or m² per litre. This is also known as spreading capacity.

Synerisis The separation of a liquid from a gel. The spontaneous exudation or

squeezing out of solvent or diluent as a separate phase which may occur
when a gel stands undisturbed. The gel structure slowly densifies but
there is no net volume change in the system.
Tape Test Type of adhesion test consisting of the application of an adhesive tape
(usually scotch tape) to a dried coating and rapidly removing the tape
with a swift, jerking motion. The coating can be either scribed or un-
scribed, depending on the specification.
Some wet adhesion tape tests are performed on latex paints after the
19 | P a g e s 2 0
 surface has been wetted with water for a prescribed time. The surface is
blotted to remove excess water then the tape test is made immediately
after blotting.
Total Solids The ingredients (non volatile matter) of a coating composition which,
after drying, are left behind and constitute the dried film.

Undercoat a) A coat of paint applied to new wood, or over a primer, or over a

previous coat of paint. It improves the seal and serves as a base for the
top coat, giving better adhesion.
b) base for an enamel.
c) Any primer, white or colored, for new surfaces.
d) Drywall primers.
Volatile Organic These compounds are the paint solvents,(excluding water) , which are
Compounds responsible for polluting by reacting with nitrous oxide and sun light to
form smog. Control is focused on deducing V.O.C content of finishing
materials, and on increasing the application efficiencies of brush, roller
and spray methods. Industry is working to reduce or eliminate the
V.O.C.’s.
Wire-wound Rod (Meyer bar, wire bar application). A metal rod wound with fine wire
around its axes so that a coating can be drawn down evenly and at a
given thickness across a substrate. The thickness of gauge of the wire
controls the depth of the wet film applied by the rod.
Yellowing Development of yellow color on aging It is most noticeable in dried film
of white paint or clear varnish. The primary cause is the formation of
color bodies due to oxidation of the oil or non-volatile (alkyd, for
example) portion of the liquid vehicle in coating. In latex paints it is
usually other causes (surfactant, dispersant, thickener, fungicide) other
than the vehicle.

Bibliography:
Coatings Encyclopedia Dictionary, Stanley LeSota, editor, published by FSCT Blue Bell PA, USA (1978).
“Coatings” Finishing Handbook 1977, published by Coatings Magazine, Toronto, ON, Canada.

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 LESSON 1 QUESTIONS

Lesson 1: Introduction & Appendix – Organic Chemistry

Up to Five of these Questions May Appear on the Midterm Examination

1. Sketch a diagramme showing the relationship between the constituents of "paint" and
comment on each of the five constituents' general role in paint.

2. Name each of the three compound groups making up the category "aliphatic hydrocarbons"
and present their general formula.

3. What is the name of the functional group -OH found in alcohol's, such as methanol, ethanol
and butanol?

4. Cyclohexane is a closed ring, or cyclic hydrocarbon belonging to the group of cycloalkanes or

naphthene solvents, what is its structural formula?

5. List at least five functional groups by their name and their structural formula.

6. Acetone and Methyl Ethyl Ketone have two chemical groups common to each other, namely
the CH3- and the =C=O. Identify the position of the groups in a structural sketch of both
molecules, and what is the name of these groups.

7. Draw the structural formula of Toluene and name the three positions where a different
group can substitute for a hydrogen atom. Pinpoint the location exactly on the benzene-ring
for each of the three positions.

8. If a neutral pH is 7, what would numbers below 7 and numbers above 7 indicate?

9. What would a chemical reaction be called that generates heat?

10. Applying IUPAC rules what is the name of the following compounds?

CH3 CH3 CH3

\ / |
CH – CH and CH3 – C - OH
/ \ |
CH3 CH2 CH3 CH3

11. Glass transition temperature is often abbreviated by a two letter symbol, give the
abbreviation and the definition of the term.

12. Describe what a "homo-polymer" is and how it differs from a co-polymer. Give at least three
examples of different co-polymer structures and name them.