by Czanne » Wed Mar 18, 2015 10:39 pm
Mungyo is what my (organic, no gmo in the cafeteria, always has a vegan option) k-12 school district uses. If they have toxins, they've gotten past a very toxin-sensitive, involved PTA. Yes, made in China, but with decent quality control.
To concentrate pastels, you will need a baby food jar or similar per color, several coffee filters, a funnel in which the filters fit, a mortar and pestle to grind the pastels, and both cool, soft (up to distilled is fine, but if you have soft naturally, tap works) water and 91% alcohol. Put the pastel dust in a tripled filter in the funnel, then slowly drip the water over the dust. Methyl cellulose is hydrophilic at temps between 20 and 40 C, so as the water flows through the dust, it will take some with and leave the pigment behind. A half stick usually takes about 60 ml. Discard the water (or refilter). The softer the water, the more calcium carbonate it will absorb and the more methyl cellulose it will wash. Let the filter dry without disturbing the sludge in the filter. Then repeat the process with the alcohol, going a little faster since the alcohol evaporates faster. The alcohol will dissolve any gums used as binder. Let the filter dry again and re grind the powder. It can be stored in the little jars as dust, or if you prefer pan pastels, you can reform it into cakes by mixing the dust with a few drops of 70% alcohol (sorry, I don't have good measurements on this one since you're looking for the texture of heavy school paste) and press the paste into the jar. Let dry again and you're ready to use with brushes. (And of course, run a test with a deep color you're not very fond of; there are environmental adjustments for local water, local humidity, and temps that I cannot control for. Use a deep for the test since pastel pastels are extended with fine calcium carbonate on purpose.)
Your kingdom is the earth on which you walk.