This is real cookery! As an alternative to etching face down in a flat dish, it is simple to use a vertical tank as supplied for etching PC boards. These are tall and very thin - about 1.5 cm wide, and big enough to take the plate that is being etched. Easy to make with two sheets of perspex spaced apart and sealed with silicone. Agitation is provided by a steady stream of air supplied to a perforated tube in the bottom of the tank by an aquarium pump. A heater, again of the sort to stop your tropical fish freezing, gets the ferric chloride to a usable 40C.
The key is to get a good quality photoresist that doesn't fail - the aerosol type has a very limited shelf-life, I've found. Cheers, John ------------------------------------------------------ Dr J R Davis Flowton, UK 52.08N, 1.043E email: [EMAIL PROTECTED]
