Egg-tempera is a very fine and durable material as long as it remains protected from insects and moisture. Lets not forget (in case of Churches) the devastating effects of lipstick, that permanently stains, with its oils, the icon. So after complete  painting, we first need to protect and then totally isolate the colors. The time of wait can vary, usually the more the better (but sometimes a week is enough, depending on the climate)

The first layer we apply is white shellac (or gomalacca), the exact liquid that you can see on the pic. Shellac comes from a natural resin secreted by a lac bug  with the name Kerria laca. We mix thin granules of clear dewaxed shellac and clear alcohol (in an approx 1:3 mixture ). Liquid shellac makes a transparent film that protects (and doesnt alter) the colors, and the fine color variations (lazure) created by the several layers of the egg-tempera technique.

Attention: One should never confuse the clear white top-coat shellac from the dark brown shellac created from flakes (in an approx 1:3 mixture ) and lower in quality alcohol. The latter is better used mostly as an undercoat in gold gilding process.

After another week of drying there are plenty of options of varnishes on the market for the final overcoat (with the strict exception of water based varnishes)

• Oil based varnishes (like olifa technique),
• Egg based varnishes (egg white) ,
• Turpentine varnishes (satin or mat effect, not gloss),
• Spay, acrylic varnish
• Wax varnishes (Bee-wax made)… 

Use with caution, let it dry completely in a dust free environment, and remember to thoroughly and tenderly 😉 clean your brushes afterwards.

For more on Top coats in icons please also visit my other post : https://angelicon.gr/varnishing-an-icon-with-beeswax/