Ink can be used to great effect in encaustic painting. You can draw or write directly on the wax and either leave it on the final layer of a painting or you can add more layers of encaustic medium on top of the dry ink. Ink, when dry, is permanent.
A Beginner's Guide to wax painting - Encaustic. What is Encaustic? Is Encaustic Toxic? Can I use wax crayons in an encaustic painting? Can’t I paint just with beeswax? Do I need to fuse every encaustic layer?