By Diane Shattuck
Note from the Editor: Most of you have had to set down the applicator and do a little mixing from time to time. Whether it’s paint for a mural or finding that perfect shade of stain for a customer’s deck, color mixing can be a very useful skill. So how knowledgeable are you about the science and mathematics of color? Here are some terms and theories that could help you in your future mixing endeavors.
To excel at color matching a keen eye is a must, along with the knowledge of the best way to obtain the desired color. The ability to see color is a critical part of the process. Understanding how color moves and how it is affected by your substrate and light are also very important to achieving accuracy. Some colors are faster and easier to achieve than others due to the type of material or application. For instance, matching a paint color is typically a quicker job than a stain match.
Since paint is a solid and not easily influenced by substrates, the opaque color has the benefit of being read and mixed much more easily. Solid colors have the option of being read by a “color computer eye” to assist with formulating the color match. The color computer eye works like this: Each color has a wavelength, the computer reads each wavelength by how light hits the sample color and bounces back. Once the wavelengths are read, a formula is presented based on the readings. Typically several readings are taken to get an accurate understanding of what makes up that particular color, then the best formula is mixed. Although a computer color match can give a formula, tweaks are often made to dial in the final color.
Stains are a bit different from paint. Since most stains are transparent or translucent and thus influenced by the type of wood they are being applied to, they cannot be read by a computer eye. Due to the color of the substrate and the transparency of the colors, the wavelength cannot be accurately read and it cannot give a clear reading. This is why stain matching must be done by the human eye.
Understanding how the colorants, the dyes and pigments used to match color, work and how their effects can influence the final color is a true art. Other things to include are how the substrate is sanded, what sealers and topcoats will be used, and if there is a glaze involved in the process.
All of these components play a part in color development and matching color. Let’s start by reviewing differences in our two main components: dyes and pigments.
Dyes are organic compounds that dissolve in a solvent such as water, alcohol and ketones. Their particle size is very small, approximately 100 times smaller than pigments particles. Dyes saturate the wood giving the effect of coloring the wood “from within.” The particle size of a dye allows light to pass through, therefore appearing transparent. The dye will change the color without regard to texture or sanding scratches, etc. The effect is much like bleach on clothes. Once the bleach comes in contact with the fabric, the color is changed. Most dyes are single colors such as red, yellow, blue, etc.
Pigments are colored pastes made up of finely ground pigment particles that are mixed with resin and volatile solvents. Pigments tend to remain on the surface of the wood, lodging in the pores and in those pesky sanding scratches. Because of the large particle size of pigments, they reflect light and may in fact obscure the wood grain if the pigment content of the stain is too heavy. Using the clothes analogy we would say they are like a stain you get on the fabric. It is evident only where it has been touched or rubbed in, and it is not an even change over the entire fabric.
Remember that all colors originate from three primary colors: red, yellow and blue. When mixing any two of these colors together we get secondary colors, orange, green and purple. Complementary colors are those colors opposite each other on the color wheel: red and green, yellow and purple, blue and orange. Complementary colors cancel out or neutralize each other. If you have too much red, add green to tone down the red. Utilizing a color wheel can help you see how to move the colors to the warm side (red, orange and yellow) or the cool side (blue, green and purple). Each color we mix can have its value changed simply by changing the ratio of how much of the primary color is involved.
For instance, orange is a blend of yellow and red. The value of each color is determined by your ratio of each color: 50 percent red and 50 percent yellow, or is it 60 percent red and 40 percent yellow? And so on. Each time, an orange hue is achieved, but the value changes. If I am looking to have more red in my color match, I can add red (100 percent chroma value) or I could add an orange that may be only a 30 percent value of red. In each case, I am adding red but with different intensity values.
Yellow is the most luminous color. It lightens and brightens other colors. Black decreases brightness or tones down a color. Color has three basic characteristics: chroma, value and hue. The chroma is the intensity or richness and purist part of the color. Value is the darkness and lightness of the color. The hue is the basic shade of color one sees when viewing the color. We consider these characteristics when wanting to adjust our color.
Color is influenced by our tinting, shading and toning. Tinting is the addition of white or lighter colors that move colors into a lighter value. Shading is the addition of black or darker colors, moving our colors into a darker value. Toning falls between the two, the addition of gray or medium color.
Outside elements also play a part in color mixing and matching and need to be considered just as much as the colorants themselves. Substrates, coatings, lighting, wood species, grain patterns, textures and how the substrate was sanded all affect the final color. Coatings, although “clear,” can have color variations ranging from amber root beer tones to ginger ale tones to water-clear and nonyellowing effects. Sheens of the coatings will flip color as well; a highgloss topcoat will have a warmer, deeper look than the same color viewed under a flat sheen. When matching a color always apply the coating before finalizing the match.
Finally, lighting plays an enormous part on how the color is viewed. The best natural light to work under is north light or daylight. Fluorescent light brings out greens and blues; incandescent light brings out the reds or warmth in the color. With all the variables that come into play when matching colors, having a good base of startup colors is a quick and easy way to reach your final match.
About the Author
Diane Shattuck is the technical service representative for Gemini Coatings. To find our more visit www.gemini-coatings.com.