Since the subject of etching with ferric chloride is under
discussion, here’s a tip to speed up the process.
If you can get hold of a magnetic stirrer such as chemists use, you
can about double the speed if etching, and keep the results clean
and smooth. A little magnet is enclosed in a plastic capsule, and
that is dropped into the bottom of your container (a round dish
works best). I cut the bottom inch off of a deli container, and
drilled many holes in the flat bottom. Then I cut what were the
sides so that only 4 or 5 small strips were left: picture a plastic
"table" with holes on it, with several short, thin legs to hold it
up over the encapsulated magnet. The work piece sits on that. The
dish sits on the stirrer, which is a black box with another magnet
just below the surface. A knob controls the rate of spin of that
magnet, and, as a result, the one in the bottom of your container.
So, when you fill with mordant, and gently turn on the
machine:voila! Wordy to describe, a snap to use. If you make enough
holes, you can effectively etch both sides, if you want to.
This woks a lot better than when I tried a vibrating table
intended for debubbling investment. The vibration set up a standing
wave, that sprouted into a fountain rising out of the niddle of the
bowl, sprinklind mordant in a 6 or 8" circular area. What a mess!