Using a clean lint free cloth, wipe a thin layer of wax over the entire surface. (inmyownstyle.com)
[8] Perhaps his most original contribution was a technique he called «monoetching,» which involved applying a thin layer of wax to an illustration board which he then scratched through with a needle. (en.wikipedia.org)
A small amount of silver nitrate encased in a thin layer of wax acts as the cathode on the other end of the paper. (treehugger.com)