Pinch the yolk so that you can hold it up, like a mother cat picks up a kitten, and puncture the egg yolk over a recloseable container. It is essential that no egg white or pieces of the egg sac are left in the solution. Add dry pigment powder which has been slightly wetted and mix into the solution until it reaches the consistency of thin gravy. The reason the pigment should be slightly wet is to keep the powdered pigment from being breathed. Never handle dry pigment without the use of a dust mask or respirator .
Dry pigment can be toxic if breathed.
If need be add a small amount of water to make the paint more fluid. Try not to add too much because a solution that is either too thin or too thick will result in cracking. Close up container and repeat procedure for all colors to be used. Egg tempera works best on a finely sanded oil-gessoed or rabbitskin glue prepared wooden panel. An excellent product to use for the painting ground is a product named Claybord, which is available in art supply stores.