Many readers will remember my Feral Watercolor Project. Well, the rabbit hole just got huge. A warren, in fact: I recently subscribed to a pigment-of-the-month club from The Wild Pigment Project in Oregon.

My first wildcrafted color arrived this week—and I'm so thrilled, one of my favorite historical colors, Mayan Blue!

The pigment is made from the indigo plant (Persicaria tinctoria) by a process of fermentation and then adding a flocculant (dispersant), then drying to a powder. Then it's mixed with a clay.

This is exactly how the Mayans made their amazing blue . . . which is featured in surviving murals and which has been found many meters thick in the bottom of deep freshwater sinks called "cenotes." The reason is that the Mayans painted victims of sacrifice with the blue pigment before tossing the hapless people into the cenotes . . . gruesome but true.

I spent a morning processing this macabre blue into watercolor paint with ox gall and gum arabic. There's a fair amount of clay so it does not disperse super freely across the paper, but the color is rich, and bonus: it mixes beautifully with yellow ochre for deep forest green.

Here is a video of the mulling process:

Readers ask, what do you add to the pigment to make watercolor?

The short answer is you need a binder (to stick the pigment together) which traditionally is gum arabic (from an acacia tree in the African Sahel), a dispersal agent, to help the pigment flow with water, which is traditionally ox gall (yes, gallbladder stuff); and a humectant, usually honey, to keep it pliable. You can mix your own or you can buy Schminke's readymade watercolor mixer, and you're done!