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Color Matching, - Color Blending

by editor 30. June 2016 11:40

By: Mitch Kohanek

Recently, I was in need of a color match on a 30 year old opaque exterior color.  It was for a few new pieces of Masonite siding I replaced on my house.  “Back in the day” that meant going to your local paint store in hopes of finding someone who had the knowledge and talent to mix colors by eye.

With today’s technology, a spectrophotometer made short work of matching an exact color for me. Gave the store a piece of the old siding, they made me a quart of paint that was a spot on color match of my old existing siding.

For transparent and translucent wood coloring using dyes, stains, micro pigments the meter comes close, but it can’t be relied on to be as accurate as it is with opaque colors. It can be a valuable tool, it has its benefits, but in many cases the color often needs to be adjusted “by eye”.

Examples:
1.    The various natural shades of species of wood like white oak.
2.    The natural colors of cherry, walnut, and mahogany.
3.    Red oak and white oak in the same pile of oak that is to be used
4.    Blending Sapwood to Heartwood
5.    Quarter sawn glued next to flatsawn
6.    Veneer next to solid stock wood
7.    New wood that needs to look like old wood colors.
8.    Refinishers who need to strip and sand down an old table top and refinish the top to look like the sides of the cabinet.
9.    What degree of translucency you are looking for.

Because of all those variables color matching is back to being accomplished “by eye”. Whether you are creating color or correcting the color, it is critical for the finisher to be in command of color knowledge.

Basically we only have two main choices of coloring agents, one which contains pigment, which I refer to as stain. Paint falls into the pigmented category. The other coloring agent is a dye, which I categorize as having no pigment. There is a third medium, the chemical coloring of wood sometimes referred to as “reactive” stains or mordants. They do not contain pigments, they are more similar to dyes.  When applied to wood they “react” to the chemistry inside the wood, such as the tannins.  Mordants are often applied before dyes are applied to achieve colors not found any other way. For now, let’s stick with the dyes and stains for understanding color.

Dyes and stains (pigments) are two different tools. Used individually they offer two different visual presentations. Used together they greatly expand the color pallet. There are manufactures that formulate their dyes and stains so they are able to be mixed together. Mixing them together can offer a one-step coloring schedule rather than two.

Approaches to mixing colors
1.    Start with a clear base medium and use stains (pigments) using the primary colors, yellow, red and blue with the addition of white and black.
2.    Start with a clear base medium and use stains (pigments) using yellow, red, black and white
3.    Use premixed colored stains. An example would be using the earth tone colors, Raw Sienna, Burnt Sienna, Burnt Umber, Raw Umber plus black and white.
4.    Use the premixed colored stains plus the primary and/or secondary colors.
5.    Dyes are sold in liquid and powder form.  Decide on using the primary colors or pre-mixed colors such as the earth tones, or use them both.

I teach a systematic approach to using any color system and it all starts with the artists’ terms of hue, chroma, value, shade and tint. When looking at a target color, the first thing to do is identify the hue. Next would be identifying the chroma and then the value of the color. If you understand color theory it does not matter which system of dyes or stains you use.

One reason to start with the earth tones or other similar colors is that hopefully one of them comes close to the target color. Choosing the first earth tone is your base color, your second choice is determined on if you need to “warm up” or “cool off” the first color. It’s not guess work, it’s an educated choice.

Many shades of making “brown” in a one-step application can be made with just one umber and one sienna. Adding a third earth tone color is not unusual. Three well-chosen earth tone colors and the proper proportions of black, white or clear base if needed produces a tremendous amount of colors.

Some finishers would rather work with fewer colors and a clear base. These finishers think of color in “parts”. Example: 100 parts yellow, 10 parts red, 5 parts black is a color. To “tweak” that color is to first understand color and keep track of your “parts”. The results are going to be the same with both systems as long as you understand color theory.

It’s worth mentioning that if you choose to use pre-mixed colors like the earth tones, having the primary colors handy is another valuable addition. An example would be knowing that red needs to be added to your mix.  Burnt Sienna is an orange Hue and is the closest color you have to red.

If the target color can’t be accomplished in a one application step, it will have to involve a color on color finishing schedule. Color knowledge just got more important. A multi-step coloring schedule could involve a dozen or more finishing procedures for a completed color. Those tools for creating color are in the form of dyes, stains, glazes, toners and paint.

I will address those tools in the next blog.

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