When we first started discussing painting the walls at Holy Cross church, we explored many options for paint. Until then, I had worked in oil paint on canvas, watercolor on paper, and in egg tempera on gessoed wood boards. Egg tempera on gessoed canvas was the first possibility I explored. That turned out to be much more expensive (because of the canvas cost) than the system we ended up using (see this post), but I did end up using canvas for a small portion of the work that would have been very awkward to reach with the scaffold.
The hierarchs in medallions were painted on canvas and then adhered to the wall. The four full-figure hierarchs were painted directly onto the wall. The hierarchs are arranged on the arch that divides the nave from the altar. Two of the full-figure hierarchs are at the base of the arch (one on each side) and two are next two them, directly inside the arch (not visible in the picture below). The center medallion on the arch is a cross, not pictured in the above gallery.