Earth Formula Rediscovered

A couple of months ago I needed another area covered with the standard earth formula, but it seemed that the original recipe did not work anymore (9,5g plaster+0.5g burnt sienna+2g orange+0.3g black). The main problem is that the estimated 0.3 grams of black dry pigment weren't that accurate - main reason was that the electronic scale's unit was 2 grams, so no way I was able to see 0.1 increments - so those 0.3 grams were actually an approximation. The big trouble with the black dry pigment is that even a small amount over the right quantity will make the formula too dark. So I dedicated a couple of hours to tests as to get a new accurate formula worked out.

The final formula is seen in the first photo, on the sheet to the right. The base is simple: 5 plaster spoons + 1/5 burnt sienna + 4/5 orange. The black pigment is not so easy to quantify, so I've taken photos with each quantity of black pigment added each time. An approximate amount of 8 times of what's seen in the second picture were added. Just so I don't forget, right now the final formula is stored in a jar labelled with 3, so for the next batch of "earth" I'll be able to have a reference while adding small amounts of black pigment.

Of critical importance to a homogeneous result is a shaker, a medium sized container, that can be closed shut and shaken to make sure all the dry pigments blend together. The one used in this case is seen in the first photo.

This post might look a little creepy, but had to be written since I'm planning to throw away the sheets of paper that were used 2 months ago for this test, sheets that contain the details of the composition they sported and I don't want the next time I'm sifting the earth formula to begin wondering why isn't the color right.