Pigment Making Exhibit

Sample

Struck by the vivid colors, I took two palm-sized samples from these strata while on vacation in Moab, Utah. One was a deep red–probably sandstone containing hematite from petrified dunes–and one was a pale blue–probably shale with reduced manganese. I decided to try to turn them into mineral pigments.

Pulverize

After reducing the stone to a fine grit with a sledgehammer, I wet-ground it further in a mortar and pestle.

Levigate

After wet grinding, I mixed the paste with about a quart of water, allowed the heavier sediment to settle, and poured off the finer sediment into a shallow sheet pan to evaporate. It took several iterations of grinding and levigation to get the mineral powder fine enough.

Dry and Store

Once I felt the mineral powder was fine enough, I let the water evaporate, leaving a thick paste, which I scraped onto sheets of paper to fully dry and store for later use.

Blue-Grey Pigment

I also crushed, ground, and levigated the blue-grey mineral using the same process as the red mineral and dried it as well.

Prepare Samples

I broke up the dried mineral paste to get small pieces for testing. Without a binder, the dry material fractured apart easily.

Blue-Grey Sample

I also broke off a piece of the blue-grey pigment for testing and refinement.

Regrind

I returned the dry pigment to the mortar to be ground into a uniform powder suitable for mixing with a binder.

Refinement

I ground the powders into a uniform consistency.

Add Binder

I decided to try Mod Podge as a binder. In a paper cup, I diluted it with water and gradually introduced it into the pigment while mixing until it reached an ink-like consistency.

Ink Testing

I tested the mixture with a steel-nib calligraphy pen and diluted it slightly further until it flowed reliably.

Detail Testing

Once the viscosity was right, the ink was capable of producing both broad strokes and thin, detailed lines.