The best crayons I have found to work with crayon etchings are
Prang/Dixon, the big crayons ... I think 12 or 16 in the pack... yellow
The best india ink that I have found is Hunt, which you can purchase by
Water down the ink by 1/3. Two thirds ink to one third water.
Brush and then scrub on the ink fairly agressively; then wipe down to a
flat film with a soft cloth.
Students will be able to see their image below, yet the contrast for
etched textures will be evident.