Dyes used in tempera

Here can be used all those dyes that are used in oil technique, and even some not used there. Partly also dyes that are used in light-resistant watercolor. Zinc white and yellow cadmiums are used here.
Zinc white hides better in tempera than in oil. Lead white is not used in egg tempera, as it yellows strongly. Umbre requires more binder and is washable with water long after drying. It often emits from the binder and decomposes casein emulsions.
To prevent this decomposition, some ammonia can be added to the umber.
Minia is more durable in tempera.
Dyes, after prolonged storage, separate from the binder and must be well mixed before use.
If they lose their ability to dissolve in water after long storage, you can add a small amount of soap to restore them.

Priming

Sometimes it is enough just to reglue the canvas with skimmed milk or a rare casein solution.
The gesso should be strong. It can be prepared on normal tempera binder with the addition of zinc white.
The best primers are adhesive and emulsion gesso.