The Difference between Dyes and Pigments

From the Keystone website:

"Many dyes and pigments are produced from the same building block chemistries, such as anthraquinone, azo, phthalocyanine, and a variety of other chemistries.

 The chemical make-up of dyes allow them to pass into their liquid state when introduced to solvents (water, alcohol, MEK, etc). The solvent molecules effectively work their way into the crystal lattice of the dye and surround the individual molecules of the dye. The solvent eventually separates the individual dye molecules in the solution, which essentially puts them into their liquid state. The final processing steps of dyes are what dictate the type of solvents they will be soluble in. For example, sulfonation will create a dye molecule that typically has water solubility. Other reactions will create dye molecules that have solubility in other solvents, but it is important to note that each dye chemistry will have its own limitations as to the degree of solubility or what is called the saturation point.

 The chemical make-up of pigments allows them to never be broken down into individual molecules, but rather they stick together in small clusters of solid state material. The solvent doesn't work into the crystal lattice of pigments, and therefore they are only held in suspension when incorporated into a liquid system. These suspended pigment systems are often referred to as dispersions, because the chemistry of the entire system is designed to disperse the pigment into the system and hold it suspended in the system.

 Pigments are often treated on the surface, so they will have improved dispersion or suspension capabilities, which allow them to remain stable in a particular system for a longer period of time. There are also methods of grinding pigments to reduce the particle size, and this particle size reduction can also be beneficial for improving the pigments ability to remain suspended or dispersed.

 In conclusion, the major difference between dyes and pigments is that dyes have solubility in some type of solvent and pigments do not have solubility. It's much like the way salt and pepper respond when they are placed in water. The salt will be soluble in the water and therefore dissolve, but the pepper will not be soluble and you will see the pepper floating in the water. The salt would be similar to the function of a dye and the pepper similar to the function of a pigment."

 So for us normal people, if you see something separated out in the bottom of the can it is pigment. Dyes don't come out of solution.


I also read on a lot of sites that dyes or pigments are better than one another. That is complete nonsense! That is like saying oak is better than walnut or pine. There are simply advantages to using each one and if you know their strengths and weaknesses it is an easy decision to make.

 Dyes are extremely transparent and absorb completely into the wood allowing for multiple applications with out sealing to get very intense or dark colors.
 Pigments sit on top of the wood and multiple applications without sealing can cause adhesion problems with the sealer and the wood. Pigments being translucent are much better at covering defects in the wood or in making glazes to antique the wood. They are also much better at UV absorption, so are much better for exterior use.

Dyes are much more prone to fading in sunlight however metalized dyes are the exception to this. They were formulated for automotive paint and are very fade resistant. As far as wiping or spraying it is about 2 things, production speed and more importantly the look of the wood. Make some samples where you use a spray only application and another where you either just wipe on and off or spray on and wipe off. When you wipe off a stain (ANY stain) you force color into the grain pores of the wood and highlight that structure more. Spraying on stain without wiping (don't allow it to puddle either) makes a much more natural look. (Like the wood was just sprayed with clear only with color)

There are some woods that look great when wiped like Oak, Walnut or Mahogany and some that look terrible, Cherry, Birch, Pine and Anigre.

Dyes and pigments can both be used as toners when mixed in a thinned sealer or topcoat to adjust color variations. Dyes are usually preferred for this but not always. 

Where do I get dyes?

Mohawk Ultra penetrating Dye Stain NGR (Alcohol base)
Sherwin Williams S 61 Universal Dye concentrate (universal base)

WD Lockwood Dye stains (water based)

Keystone Nerosol Dyes (multiple solvents)

Transtint Dyes (alcohol and water)