Making —Transparent yellow oxide watercolour paint


Current procedure — last updated 26. December 2022

  1. Mix the watercolour paste
    1. Wear a mask. Go outdoors - this can be very messy.
      Pour the medium into the stainless steel container first.
    2. Measure out the powdered pigment.
      Add about a third of it to the Blender Ball, and then top off with about 250ml of medium.
      Seal it up and shake back and forth 60 times.
      Repeat twice more, and then pour in the remaining medium and shake to roughly rinse.
    3. Start dispersing, using a dispersion disc in a drill press.
    4. Cover the bowl while dispersing to limit the dust.
  2. Mill the paste
    1. Set both rollers to 6mil.
    2. Prepare a large bowl and a hopper to use. Find a stand to raise up the bowl to catch the paint to reduce splashing.
    3. Use a nail brush and water to clean the rollers at the end of the first runs.
    4. Put through the mill 17 times.
    5. Test for grind at the end of run #4, #6, #8, #10, #16, #17, and #18
    6. At the start of run #17, add one drop of clove oil for 250ml of total medium (100ml mix = 4-5 drops) Add the oil to the paste on the slow rollers, rather than in a bowl on in the hopper.
  3. Package into pans
    1. Arrange the 450ish empty 2ml half-pans into rows on a cookie sheet
    2. Fill the pans to the top with a pipette set to 9.5ml
    3. Allow to dry, and then top off
    4. Allow to dry, and then package into wax paper bags

Drapak’s manufacturing notes

30. August 2022 - 1 batch of 150g pigment: 1000ml medium
Py24h powdered Transparent yellow oxide brown pigment: 150 grams × $0.11/g = $16.50
Watercolour medium 1000ml × $23.09/1000ml = $23.09
Number of pans filled = 287 430 pans used × $0.08/pan Cost of pans = $34.40
Total for materials = $73.99 Material cost/pan = $0.26
Time to mix 10 minutes
Orotan added 15 ml
Time for pre-dispersion 20 minutes
Time to mill 160 minutes
Time to dispense 150 minutes
Total time 340 minutes
Number of runs 17
Final grind size 10-15µm
Time spent per pan 1.18 minutes × labour rate $0.445/min= $0.53
Total cost/pan = $0.78

My god this was tough to mill.

It was just like Quinacridone Violet in that it simply refused to disperse at first. Ten runs and no real difference.

But then I got the courage to add 15ml of Orotan dispersant. And things changed quickly. Suddenly the colour changed from a dull brown to an orangier colour. The texture of the pigment changed as well. It was no longer rough and spiky when dried on the test paper. It started to show a little bit of foam, which thickened the paste a great deal. I should have added more water to it, but I did not. I should have added a little more Orotan to it as well, I think there were still some bits that were not fully dispersed.

Orotan was very cool, though. I think that I will have to try adding it to the next batches of Quinacridone Violet. The change to the colour is pretty amazing.

Dispensing was miserable. The paste was too thick to go through the stepper and was badly constrained. My guess was that the Orotan added tiny bubbles to the mixture. I think I will swap out the older stepper driver for speed, though.

TODO: Make sure that I add more water before beginning. Add 15ml of Orotan to the mix at the drill press. Swap out the stepper driver. Consider adding more Orotan if needed in order to get the spikiness reduced.