TRADITIONAL TECHNIQUE

egg tempera (pigments and egg yoke medium used by painters until the XV° century when oil painting was invented and still used by iconographers for its fluidity, transparency and longevity. Fra Angelico used this technique)
gold leaves 23 Karats (full background or only halo)
quality solid linden board made in Italy. (other wood can be used, even plywood)
with or without cradle (carved frame) and braces in the back (depend on size)
gesso: 10-12 layers of a compound of calcium carbonate and animal glue on a fabric glued to the wood serving as a white porous base for the painting: holding the layers of paint when the wood is "working" and absorbing the excess water from the floating.
floating technique of painting (Russian tradition) which allows a beautiful transparency evocative of the spirituality of the icon and a reel collaboration with the Holy Spirit because you cannot control it perfectly (akin to watercolor). Demand a long time of drying between layer and after completion.

Because of these specificities, this technique is the most difficult and long but there is a spiritual depth and quality that no other technique can match.