All of the paint store pigments I know about at this point are blended into some kind of liquid, most often water, though that’s not the case for pigments used in oil based paint tinting. For now I’m focusing only on pigments for water based paint tinting (latex, acrylic, etc.).

My current process is to dehydrate the pigment, and then rehydrate it. There are a few reasons:

- Dehydrated pigment takes up so much less space. The space needed to store nearly empty quarts adds up quickly. For efficiency I like to accumulate quite a few of a given pigment before mixing it with binder, and I'm still in my prototyping phase. The neighborhood hardware store I’m working with easily generates 10-20 “empties” per week. My metro area of about 170,000 people has 8 stores that I could be collecting from, most of which are bigger. If I was seriously making paint I could be picking up hundreds of empty quarts/containers a week (hopefully with the help of a like-minded team.)

- If I’m dehydrating, I can rinse the cans out onto my sheet, instead of meticulously hand scraping. This is a huge time saver, and eliminates a really tedious task.

- It’s easier to create reproducible recipes with dry pigment. Working with weights instead of volumes is significantly easier and more accurate. It also opens up the potential for blending pigments to create other colors.

- If I want to use pigments to make oils or encaustics I’ll need them to be nearly moisture free.

- When making watercolor pans, the usual process is to fill part of the way, let it dry, fill more, let dry, and so on. Most watercolor pans have 3-5 layers in them. Adding binder that’s dispersed in water to pigment that’s dispersed in water makes a paint with really high moisture content. This would result in either lots of fill layers, and/or really long dry times.

- Dry pigment is much more resistant to mold when being stored. For short term work mold isn’t a big concern, but if you allow hydrated pigment to sit for a while before processing it would become a concern.

I received a very helpful comment from pmaitrot saying, among other things, that the three roll mill is overkill for pre-dispersed pigments. I totally see where they're coming from. My choice to go with this option has a few layers.

First, I've tried to hand process dried pigment with hydrated watercolor binder, and I was able to do it but it was *work*. It took a while and a lot of physical effort to get to a paint I really wanted to use. They recommend trying a dissolver disc, and that's something I will be experimenting with.

They also suggest looking for a used milling machine. In Germany they found a used one for about 50€ which is fantastic, but in my searches I'm rarely able to find one in the US for less than $1000, the cheapest on eBay right now is $929. And even if I was able to score a cheap machine, that still doesn't address my intention to make this into an easily reproducible system. There's a huge amount of pigment being thrown away every day, and there's probably an even larger amount of underfunded arts programs that could benefit from this. Lots of localized processing means less wasted time and transport, and more community ownership.

The other reason I'm thinking of going all in with a milling machine is a really about human nature. Sure, people will start with my instructions and recycling prepared pigment. But then someone will think how holographic glitter or iridescent resin pigment dust would make a really cool paint. Someone else will have some dried turmeric that's such a pretty color, and could that be paint? A dissolving disc probably wouldn't be enough to get all of those things made into paint.

And finally, a machine built by the owner is also maintainable by the owner. If something goes wrong, they aren't trying to figure out how to repair or replace an obscure piece of lab equipment, they can just go buy a new dc motor to swap out with the bad one.

At this point I'm waiting on shipment for some parts I've ordered to prototype with, so I'm drying out the pigment I have so I'm ready to get to work when I can I really appreciate the feedback so far, so if you have comments I'd love to read them!