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The Basics of Coloring Wood

One of the keys to understanding finishes.

So you’ve completed your project and now you want

to color it so it matches another object, a color chip or
a vision you have in your head. Achieving this match
can be one of the most difficult tasks in wood
finishing, but before you get into the actual mixing of
colors, it helps to understand what’s possible and
know the “tools” you have at your disposal.

The Wood

Any color can be matched, but not any wood. You

have to pay attention to how the wood or woods The same stain was applied to the
you’re finishing compare to the sample you’re trying left side of each of these woods --
to match. There are four large categories of woods: from the top down: oak, pine,
softwoods such as pine and fir; tight-grained mahogany, maple. Yet each still looks
hardwoods such as maple, birch and cherry; medium- like the wood it is. There are limitations
grained hardwoods such as walnut and mahogany; in what you can accomplish making
and coarse-grained hardwoods such as oak and ash. one wood look like another.

Within each of these categories, you can pretty

successfully match any two woods using some
combination of bleach and stain. But trying to match
woods of two different categories has its limitations
because of the large differences in grain and figure.
You should take these limitations into account when
you’re choosing the wood for your project.

Types of Stain

The basic way to change a wood’s color is to apply A full-strength stain was applied to
stain. In choosing a stain, you need to take into the left side of this oak. The same

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account the four ways in which they differ besides the stain thinned half with paint thinner was
obvious variances in color. applied to the right side. The ratio of
colorant (pigment and dye) to liquid
• Type of colorant: There are two types of colorant (thinner and binder) determines how
used in stains: pigment and dye. Pigment is finely dark the wood will be.
ground natural or synthetic earth. Dye is a chemical
that dissolves in a liquid. Everything that settles to the
bottom of a container is pigment, and all the color that
remains in the liquid after the pigment has settled is
dye.

Pigment is better at highlighting grain if the excess is

wiped off, and at obscuring the wood if the excess is
left in any thickness on the surface. Dye is better at
changing the color of wood without muddying it —
especially dense woods such as maple. Some stains
contain only dye, some contain only pigment, and A green toner was applied to the
some contain both. right side of this mahogany to “kill”
the red and turn it brown. Toners can
• Amount of colorant: Stains differ in the ratio of be used to adjust color after the
colorant (pigment and dye) to liquid (thinner and application of a stain.
binder). The higher the ratio of colorant in the first
coat you apply, the darker the stain will make the
wood. You can control how dark you color the wood in one application of stain by adding pigment
or dye to increase the ratio or by thinning to decrease the ratio.

• Type of binder: Most stains contain a binder, which seals the pigment or dye into the wood or
onto its surface. Binders are oil, alkyd, oil/alkyd or water-base finish. The biggest difference
among binders is drying time — oil dries slowly, alkyd and water base dry rapidly. But also
important is water-base stain’s characteristic of raising wood grain. Some dye stains, usually
identified as “non-grain-raising” (or NGR), “water-soluble,” or “alcohol-soluble” don’t contain a
binder.

If a stain contains a binder, every coat after the first remains on top of the wood; it doesn’t go into
the wood. Pigment in these stains obscures the wood if some is left on the surface. Dye in these
stains is fairly transparent. Dye without a binder continues to add color into the wood and darken it
more with each coat.

If you apply a pigment or dye stain over a sealed surface and leave it, the stain is called a toner or
shading stain.

• Thickness: Most stains come in liquid form for fast and easy application, but some are thick gels.
Gel stains are useful for reducing blotching on woods such as pine and cherry, because gels don’t
penetrate into the wood.

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Just as with liquid stains, the color in a gel stain can be adjusted by adding pigment to darken or
tweak its color, or by adding a clear gel finish to lighten its color.

Gel stains are usually labeled as such, but manufacturers rarely provide much information about
the type or amount of colorant or binder. To a large degree, you have to experiment and learn by
trial and error, and this is the primary reason many people find staining so problematic.

Application Methods

The basic way to apply a stain is to wipe, brush or spray a wet coat onto the wood, then wipe off
the excess before it dries. This will produce an even coloring as long as the wood isn’t naturally
blotchy and you have prepared it well.

Other ways to apply color include the following.

• Spray on a stain and leave it (called “toning” or “shading”). You can spray an entire surface to
produce an even coloring, or you can limit the spray to parts (for example, just sapwood) to correct
an uneven coloring in the wood or create special effects. You should thin the stain with four-or-
more parts thinner to prevent lap marks.

You can also tone or shade using a brush, but it’s difficult to keep the coloring even.

• Partially seal or “washcoat” the wood before applying a stain. A washcoat is any finish, sealer or
white glue that is thinned to approximately 3 to 7 percent solids so it seals the wood just enough to
prevent deep stain penetration and the resulting blotching on some woods.

Most finishes are 20 percent to 35 percent solids right out of the can, so thinning the finish 5-1
usually gets you in the ballpark.

When staining large or multiple objects, using a fast-drying, sprayed-on washcoat followed by a
liquid stain is more efficient than using a gel stain, but experimentation and practice are necessary
to learn the right amount of washcoat to apply. A gel stain is far more predictable.

Slow-drying washcoats, called “stain controllers” or “wood conditioners” are designed for wipe and
brush application, but they also take experience to use successfully.

• Seal the wood with a sanding sealer or first coat of finish and apply a glaze to create a special
effect. (See Popular Woodworking, April, 2000, page 76.) A glaze is a pigmented stain thickened
enough so it stays where you put it. You can use rags, brushes or specialized glazing tools to
manipulate the glaze. Once you have the look you want, let the glaze dry, then coat over it to
protect it from being scratched or rubbed off.

• Seal the wood with a sanding sealer or first coat of finish and spray on a toner or shading stain to
change the color of the wood or highlight parts of it. Toners and shading stains (the terms are

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often used interchangeably) are very useful for tweaking a color to an exact match.

Remember that a pigmented toner obscures wood while a dye toner doesn’t, and that over a
sealed surface, toners and shading stains add color but don’t bring out the wood’s figure.

Conclusion

Every color-matching situation is different, and many are very challenging. Once you’ve
determined the degree the wood will allow you to be successful, achieving a good match involves
choosing types of stains and methods of application in addition to choosing the right color. PW

Bob Flexner is a contributing editor for Popular Woodworking.

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