Making ochre paint by hand part 2 - Improving the pigment

Real, honest, hand made ochre paint

A few weeks ago I made a post about creating ochre paint by hand. I've been experimenting since then and I've improved the process.

I should mention that I'm deriving the ochre from rocks, not clay which is apparently how it's normally done. I haven't come across any local clay which seems like it would be useful for pigments... in fact, I'm not even sure what I should be looking for as far as clay goes. But I have walked past many rocks with interesting colours, and that's why I decided to turn them into paint.

Basically I'm just making it up as I go along. I haven't been taught any of this, but I'm sure someone has been using a similar method for perhaps thousands of years, who knows.

The main problem with the first attempt was that the pigment was not fine enough. It was inconsistent, Grains were visible when applying paint, and once it dried the surface felt a bit like sandpaper. When I brushed my hand firmly over the surface little bits would crumble off. I mostly solved the problem by mixing it into professionally manufactured oil paints. The ochre still came through and it helped get the colours I was after. View the painting here.

But I wanted better results so I can paint some pictures based entirely on pigments I have made. Pretty sure I'm just about there. Here is the process I've come up with:

Coarse particles left over from step 3

1. Find rock/s with a colour you like. Clean them to get rid of any impurities like bits of dirt and plant matter. We don't want that in our pigment.
2. Grind down rocks with a mortar and pestle. Add some water to prevent dust going everywhere. This also appears to help grind it down into finer particles, and it's easier to work with the paste it creates. This part can take up to a couple of hours. Don't put pieces larger than 1cm into the mortar as you're grinding. Break the rock into small bits beforehand.
3. Add some more water to thin out the paste and pour it into a jar. The largest, most useless particles will sink to the bottom of the mortar as you're pouring. Do this a couple of times to make sure you're getting as much of the good stuff as you can. 
4. Let the jar sit for about half an hour. Only the finest particles will still be suspended in the water. Pour this water into a second jar. I repeated this a couple of times, refilling the first jar with water and pouring off the top into the second jar.
5. Time to remove all the water and claim our pigment. After letting it settle for about 24 hours, pour off as much water as possible without losing any ochre.
6. Pour that into an oven-safe vessel of some sort, and chuck it in the oven for a couple of hours at about 100 degrees C.
7. Once the water has completely evaporated, you're left with dust which has solidified but will easily break down again when you add oil and crush it a bit with a palette knife.

This seems to work really well. The pigment has a great consistency and is easy to paint with. I'm not sure how durable it is yet, it'll be interesting to see how it behaves when dry for a while. I'm just about certain it will never, ever fade.