You will need:
water, 1 liter
gum tragacanth, 10 g
Champagne chalk / Bologna chalk
sodium benzoate, 1 teaspoon
glass plate, 30 x 30 cm
water and detergent to clean equipment and brushes
filling knives, 2
pipette / medicine dropper
kitchen towel, paper
Dissolve 10 g gum tragacanth in 1 liter water. If needed, add 1 teaspoon sodium benzoate as a conservative. This mixture is your binder. Place the glass plate on a flat surface with a sheet of white paper under the glass. This shows the colours clearly. Place a rounded tablespoon of pigment on the plate and moisten with the gum solution. Using the knives, mix the pigment and gum thoroughly, adding a little gum solution as needed, until you get a clay-like consistency. Do not add too much gum solution. The clay should be as dry as possible. Use your hands to knead the clay mass. It should not stick to your hands. Roll a crayon with your hand on the glass plate. Clean the plate and knives with paper kitchen towels. If you want to make a series of shades, from pure pigment to a lightly tinted pastel, repeat the above procedure using champagne chalk only. Cut the plain chalk crayon in two. Knead one half with the pigment crayon. Continue until you have the range of shades you want.
Tip: Titanium white can be used instead of chalk.
Allow the crayons to dry naturally in the sun or in a warm spot indoors. If you use an oven or stove they will dry too fast and crack. Natural pigments are very good materials for these pastels. Synthetic pigments are often difficult to knead. Wrap the pastels in cigarette paper. If you want a hard crayon or pavement chalk, then use Bolognese chalk rather than Champagne chalk. If the crayon turns out too hard, add more water to the binder.