Why hand mull pigments into paint? There are two basic reasons for doing so: To break down agglomerates of pigment particles and to evenly disperse pigments into the paint. Most artists are aware of the need to smoothly mix pigment with a binding medium, but few are aware of how breaking agglomerations of pigment particles can also improve the saturation of the paint color. Fewer still know about the possibilities that grinding pigments afford for altering the visual appearance of pigment in paint.
Dispersing pigments into a paint binder with a muller on a flat surface helps to breakdown agglomerations or pigment particles that have clumped together from moisture and other weak binding forces. This helps to not only make the final paint smoother in texture, but improves on the opacity and color of the paint. However, it is a common mistake to think that the force of mulling actually grinds pigment particles into smaller sizes. Greater mechanical force must be applied in order to do so. One way to do this is with a mortar and pestle. A pestle directs the entire force to a singular point whereas a muller applies the same force spread out on its bottom flat surface. In addition, the pressure applied to the concave surface inside a mortar creates greater lateral forces to shear the particles in smaller ones. The action of grinding in a mortar can reduce the particle size of the pigment, and in some case altering its color substantially.
Not all pigments improve in color and appearance by being ground to a very fine powder and then mixed with a binding medium. For example, the natural mineral malachite loses its color saturation the finer it is ground. On the other hand, some pigments, like cinnabar and lazurite improve their chromacity when grinding to the finest possible particle sizes.1
Many synthetic pigments available to artists today are already prepared in extremely fine grades, since they are essentially made from precipitated chemical compounds. Whereas this makes for very uniform and small pigment particles that offer some advantages in covering power and tinting strength, it also removes the interesting textures and intense chromacity found in natural pigments. At the very least, it does not allow the artist to control the pigment to its best potential in painting. Grinding pigments gives you the tools to overcome this limitation.
Rublev pigments from Natural Pigments are made to careful specifications that do not destroy the pigments best qualities and also allow the artist to refine them for his or her own use through elutriation or grinding. Many Rublev pigments are basically raw materials that may require further processing by the artist to achieve certain desirable effects. Rublev pigments can be used as they come out of the jar or you may grind them to smaller particle sizes and separate into different grades for special visual effects. As you become more aware of these possibilities, you may want to experiment, paying close attention to the way the pigments look when mixed with your medium, whether it is oil, egg, acrylic, casein or gum Arabic.
Tools Needed to Make Paint
The tools you need to disperse pigments and make paint are quite simple and most are available locally. For convenience, Natural Pigments has put together an Introductory Paint Making Kit to help you get all the tools and materials you need to get started. Here are the tools you will need to get started:
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Item |
Where To Find |
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Muller |
Glass, stone or ceramic muller
Glass muller, large (Item No. 640-GLMLL), also small and medium sizes are available
Included in the Introductory Paint Making Kit (Item No. 601-1101)
Also available from select specialty art supplies stores |
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Mulling surface |
Plate glass at least one quarter-inch thick, marble, granite or other smooth, non-porous flat surface.
Included in the Introductory Paint Making Kit (Item No. 601-1101)
Also available from glass shops, marble and tile shops |
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Spatula, palette or putty knife |
Spatula (Item No. 652-PT409739)
Also available from hardware stores and art supplies stores |
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Silicon Carbide |
Also known by its tradename, Carborundum. It is best to use 100 grit to prepare the surface.
Silicon Carbide 100 grit (Item No. 670-1201)
Included in the Introductory Paint Making Kit (Item No. 601-1101)
Also available at select hardware stores |
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Distilled water |
Supermarket or food stores |
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Gloves |
Latex gloves, powdered are best for ease of putting on or removing (Item No. 660-2100)
Also available from pharmacies, drug stores, and medical supply stores |
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Respirator |
NIOSH-approved dust respirator (Item No. 661-2600)
Also available from hardware stores |
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Eye Protector |
Eye Protector (Item No. 660-3100)
Also available from hardware stores |
CAUTION: Always wear a NIOSH-approved dust mask while grinding or working with any dry earth or pigment. Wear protective clothing and gloves while working with pigments in any form -- dry or wet.
Preparing the Surface
The mulling surface must be roughened before it is useable for dispersing pigments. You will need about 15-20 minutes to prepare the surface for dispersing pigments. Here are the steps you should follow to prepare the surface:
Step 1: Place the surface on a firm support such as a countertop or firm table. If you are using glass as your mulling surface, you may find it helpful to put a white washcloth or a white kitchen towel beneath the glass to stabilize it while grinding.
Step 2: Pour a small amount of silicon carbide onto the surface. About 1/8 of a teaspoon will be fine to start with. Apply distilled water to the silicon carbide a drop at a time to make a stiff paste.
Step 3: Mix the water into the silicon carbide to make a paste the consistency of toothpaste.
Step 4: Place the muller onto the small pile of silicon carbide paste and begin moving it a circular motion reaching to the edges of the surface. The corners of the mulling surface do not need to be roughened. Continue to grind in this motion for 5 to 10 minutes.
It will be necessary to remove accumulated silicon carbide paste from the sides of the muller using a scraper, palette or putty knife. Periodically scrape the paste into a small heap at the center of the mulling surface in order to continue grinding. When you have completed grinding the surface, visually inspect it to see if it has been roughened by holding it up to a light at an angle. If the surface was smooth and shiny to begin with, you should notice a matte appearance where you have been grinding.
To avoid contaminating your pigments, clean your tools well by washing with soap and water.
Mulling and Dispersing Pigment into Water for Water-Based Paint
Now that the mulling surface has been prepared, you can begin to dispersing pigments and making your own paint. Lets mull some pigment intended for use with water-based mediums, such as egg yolk (tempera), hide glue (distemper) or gum Arabic (watercolors). Disperse pigment only in distilled water. Tap water may contain a high amount of minerals and perhaps bacteria that can contaminate your paint.
Step 1: Place a small amount of pigment in a heap at the center of the prepared surface. Start by working with about 10 grams of pigments.
Step 2: Add a small amount of distilled water to the heap of dry pigment a few drops at a time. Do not add too much water to start.
Step 3: Mix the water into the pigment with a spatula, palette or putty knife. The correct amount of water is added when the pigment has the consistency of toothpaste. It is easier to judge the thickness of the paste once you begin grinding with the muller. Hence, in the beginning it is better to begin grinding with a stiff paste than one that has excess water.
Step 4: Holding the muller firmly with the heel of your hand down and your thumb up, slowly move the muller in a circular motion while keeping the pigment in the center of the surface. The pigment will slowly accumulate along the outside of the circle. Use the spatula to move the paste to the center of the mulling surface in order to continue grinding.
If the paste becomes too stiff, add more water a few drops at a time. Do not worry if suddenly the pigment is thin and watery. Simply add more dry pigment to the mixture.
Periodically lift the muller from the mulling slab and remove any accumulated pigment from the sides of the muller using a spatula, putty or palette knife.
Sometimes suction will form between the muller and mulling surface making it difficult to move or lift the muller. Use the spatula as a lever to raise an edge of the muller. Then slide the muller horizontally off the mulling surface.
To prevent contaminating your next pigment, clean your tools very well. If you have been grinding with water-based media, wash with warm water and soap. If you are mulling with oil, clean up with turpentine, mineral spirits or lacquer thinner. Always wash your mulling tools with warm water and soap after cleaning with solvents. You may remove caked-on pigment and paint by mulling with any kitchen scouring powder, borax or pumice with the muller on the mulling surface. Follow this by washing with soap and warm water.
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