I have been searching for a material that I can include in my cave paintings that would allude to layers, or 'excavating down' into the painting. I tried using plaster but found it difficult to use because of its fast drying time, and it was difficult to get the consistency correct. It crumbled as I worked, and it was inconvenient to use because of the dust that is created.
Inspired by the thick wax paintings of Anselm Kiefer, I settled on using a wax paste, which was a mixture of wax and oil paint. I used the below recipe to create the paste, however, it was prone to cracking after it had cooled, so I added a step of mashing it using a pestle and mortar which made it into a nice smooth consistency before I added the oil paint just before using it.
Wax Paste Recipe:
1 part beeswax, 1 part turpentine. Over an electric hotplate, warm the ingredients together until the beeswax has melted into the solution. Remove from the heat and stir occasionally until the solution cools to a soft paste.