Making —Burnt umber 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 10 times.
    5. Test for grind at the end of run #4, #6, #8, and #10.
    6. At the start of run #9, 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 350ish empty 2ml half-pans into rows on a cookie sheet
    2. Fill the pans to the top with a pipette set to 4.5ml
    3. Allow to dry, and then top off
    4. Allow to dry, and then package into wax paper bags

Drapak’s manufacturing notes

24. December 2022 - 1 batch of 150g pigment: 1000ml medium
PBr7 powdered Burnt umber pigment: 150 grams × $0.044/g = $6.60
Watercolour medium 100-ml × $23.09/1000ml = $23.09
Number of pans filled = 314 470 pans used × $0.08/pan Cost of pans = $37.60
Total for materials $67.29 Material cost/pan = $0.14
Time to mix 22 minutes
Time for pre-dispersion 10 minutes
Time to mill 225 minutes
Time to dispense 60 minutes
Total time 225 minutes
Number of runs 10
Final grind size 5-15µm
Time spent per pan 0.72 minutes × labour rate $0.445/min= $0.32
Total cost/pan = $0.53

This is a very well behaved pigment.

I did 10 runs on the mill, but I am not sure if the 9th and 10th runs truly helped.

Dispensing was still irritating. I am even wondering if I should shift back to the old stepper drive. It was loud but fast. I might want to change the interface to having options for the number of steps rather than the number of mls. It would be more accurate.