Greg Dermer wrote...
What is the electrolyte used?

For stainless, I hear that the commercial ones are best, but I don't
know from experience. Last summer, I got samples of three different
electrolytes from IMG, intending to experiment with them on different
steels, but I haven't got round to doing that yet. The price was very
reasonable -- if I recall correctly, the samples were free (I was
ordering stencil material at the time). If they did charge me for the
electrolyte, it was something like five bucks.

My contact was Patricia Bruno, and she was very helpful. She also
mentioned something about an inexpensive "knifemaker's sample pack" with
five different electrolytes that they were planning to offer.

http://www.img-electromark.com/catalog3.php

Snoop around their web site for some good basic information on the
process and equipment in general.

Anyway, I have used the SC-50 on O1 and it works very well. However, I
have also had good results with a homebrew electrolyte composed of about
equal parts of potassium chloride and salt in water. It works even better
with a bit of muriatic acid added. I had been experimenting around with
this before I got the stuff from IMG, and it worked pretty well. I got
the "recipe" from a paper on sheet metal strain studies.

The original recipe in the paper was:
potassium chloride, 80g
sodium chloride, 90g
nitric acid, 100ml
hydrochloric acid, 100ml
water, 4.5L

I didn't have any nitric acid, so I just winged it with what I had on
hand and it worked well enough. I had previously tried various
concentrations of just salt and water, with poor results.

BTW, the whole process is well within reach of the do-it-yourselfer. I
made both the light box to expose the stencils and the electro-etcher for
a fraction of what commercial units cost, and all from information
available on the web.

Good luck!

Jim