Tempera protection

Tempera after drying has a pleasant matte tone, which is especially beneficial for wall painting.
Easel paintings made with tempera can be covered with varnish (the same that is used in oil technique).
To ensure that the painting does not change its tone, before varnishing, its surface should be covered with a 4% gelatin solution. This will isolate the varnish from the painting layer and lay over it.
The varnish gives a deeper tone to the colors and protects from dirt and external injury.
Palettes for tempera are metal with recesses for the paints. Brushes like those used in the oil technique, but with slightly longer bristles.
So that the paints do not dry too quickly and allow them to model longer, you can paint with tempera on unprimed canvas, soaking the back of the painting with water.
Well-made tempera does not darken and, unlike the oil technique, does not change its tone over time.
The process of its drying is quite different from oil. Only in the first stage of drying does the tempera change its volume, further on it remains unchanged. This greatly affects the durability of the painting.

Disadvantages of tempera:
1. speed of drying of paints.
2. change in tone during drying.