Bill Gilmour's video: How To Etch Steel

Here is a fairly simple way to etch steel. This method does not use ferric chloride since this is not always available easily. Instead, we will use vinegar and salt as our electrolyte, and a 12 V battery charger will supply the needed power. The steel piece is masked using nail polish as etch resist and the design is scratched through the dry nail polish with a sharp pick or a large needle. The red (positive) from the battery charger goes to the steel to be etched. The negative goes to a small cotton pad moistened with vinegar and salt. The pad is touched to and moved around on the area to be etched. Don't stray off the nail polish with the pad or you will etch unintended places. 30 seconds will give a light etch, several minutes will give a deep etch. Make sure that the nail polish layer is thick, or put two coats to be sure. After etching, clean off with acetone or nail polish remover on a rag. The process is shown on two work pieces, a stainless steel ruler, and a utility knife that I made from O1 steel.