So I decided to give the steel engrave thing a try for one of the professors here looking to make a gift. I went with the paper towel, damp with water, method because it looked the best from what I’ve seen here. 1/4 way through, it was dry and no longer covering the knife. But it was still working, so I let it continue. This is the result:
Nice marking of the knife.
With the 304 stainless that I have tested, the presence or absence of wet paper towel had no effect.
However, wetting the towel with epsom salt (Magnesium Sulfate) did result in darker engraving. This is similar to an effect that others have seen using a slurry of Plaster of Paris (Calcium Sulfate). The sulfate enhances the marking on some stainless alloys. A gel containing epsom salt would probably work better as there would be better contact. I have not got around to trying this yet.
Good knives are not made from 304 alloy as it does not hold an edge very well.