Engraved Blank unglazed ceramic tiles
Mixed Titanium Dioxide (TIO2) with 70% Alcohol (1 part TIO2 to 3 Parts Alcohol) put in spray bottle and shake well. Spray a thin even layer and let dry, Repeat.
After engraving rinse the TIO2 off with warm water and soft brush. The tiles I bought came with cork backing. after it dries peel the backing off the cork and and stick it on.