by Deb Shaw
John Cogley and Kathrine Taylor of Daniel Smith, gave a fascinating presentation on the pigments and processing methods they use to create Daniel Smith paints.
John Cogley, President/CEO and Founder of Daniel Smith, talks over some paint tests with ASBA Conference attendees.
How rocks become pigments
The multiple-step process begins with the Daniel Smith geologist adventuring out all over the world to search for mineral resources. Acquiring material is rife with problems: countries may decide they no longer want to export minerals; borders close; or mines run dry.
Sugilite, rhodonite, serpentine, ryanite, garnet and more—mountains of minerals arrive for processing. Many start out the size of a person’s torso. John explained that they fracture the rock, rather than grind it. His analogy was the difference between table sugar and powdered sugar: fracturing the rock until it is very fine keeps the crystalline structure intact, so it refracts light. Grinding would make the pigments dull and lifeless, like powdered sugar.
The challenge in creating quality pigments is overcoming the electric static of the individual particles, which makes them want to attract and clump together. This natural tendency to agglomerate creates pigment “lumps,” which leave hot and cold spots in the paint application. Multi-stage machine processing enables the pigments to lay in an orderly row, giving maximum refraction and maximum color.
The rocks are squeezed in the first machine until they fracture. Successive machines gently hammer them, and then roll them through balls, until they are the size of grains of rice. From there, they are run through heavy, hardened steel rollers. The hardened steel rollers have a hardness of 7, and some of the rocks have a hardness of 8 or 9; so the massive rollers need to be replaced annually (at least!). Each roller costs upwards of $50,000.00.
Once the pigment is at its final size, the mineral is run through various solutions. Specific gravity separates out the impurities, and the pure pigment is ready to be mixed with gum arabic and packaged.
Daniel Smith only uses medicinal grade gum arabic for binding, as it is consistent in quality.
Each batch of color is tested and carefully recorded at Daniel Smith. Photo by Deb Shaw.
It’s all about the size of the particles
Different minerals are reduced to different sizes, depending on the color desired. For example, French Ultramarine has larger pigment particles than Ultramarine. This means that French Ultramarine particles have more surface area and will reflect more “red” back to the viewer than Ultramarine.
The smoother the pigment and the purer the pigment, the less granulation will occur when applying the paint.
Garnets in their matrix, on top of Daniel Smith Garnet Genuine test page. Photo by Deb Shaw.
Granulation, or reticulation occurs when three or more pigments in a color behave differently when applied to the paper. If you look at a greatly enlarged side view of a sheet of paper, it’s apparent that it isn’t smooth and flat, but has hills and valleys. The pigments in a granulating color will separate out and settle out at different points on the paper, based on the specific gravity or density. The lightest pigment (frequently synthetic pigments) will “float” and stay on the top of the hill. The next heaviest pigment might flow downhill a little further, settling in on the “side” of the hill. The very heaviest pigment will sink all the way to the valley and remain there. The purer the pigment and the smoother the paper, the less granulation there will be.
Synthetic colors, such as the Quinacrodones, are very pure, very smooth, and have exceptional lightfastness. They are used by (and dictated by) car and other industries. In the Quinacrodone family, different colors are created by moving the bonds around in the molecule.
Testing of pigment, showing the original pigment “rock” with the swatch test. Photo by Deb Shaw.