This was a question posed to me on Twitter so for those who don't know what it is here is a brief explanation.
Traditional etching techniques involve exposure to some extremely hazardous chemicals including a requirement to have extraction units to deal with harmful gases given off during the etching process, exposure to white spirit, to clean hard and soft grounds (or resists) off the plate. etc.
Printmakers who are in regular contact with these chemicals in their printmaking practice began to look for ways to reduce their exposure to them. I think I am right in saying that Keith Howard, author of The Contemporary Printmaker is the established guru of this method of etching joined by many others since.
Essentially the 'resists' we use have an acrylic base, and are removed by soaking the plates in "Speed Stripper' normally used for stripping polish off floors. Copperplate is etched in ferric chloride and aluminium and zinc are etching in copper saline sulphate neither of which give off harmful gases so there is no necessity for extraction units.
Finally, the use of ferric chloride means it takes a long long time before you have to consider how to dispose of the sludge at the bottom of the tank. If using copper saline sulphate to etch aluminium it is easier to dispose of the resulting liquid and sludge if you add salt to the spent liquid. The liquid is left then to stand until it turns clear and it can then be poured away. The sludge should be separated and can be put out with the rest of your waste for normal waste collection according to Peter Wray. ZInc is less easy to dispose of because the resulting sludge is toxic to fish and water born creatures and must therefore be handled with care and definitely not poured down the sink. It is advisable however to read up on it carefully and follow the instructions before you embark on experimenting yourself so that you are fully aware of the health and safety considerations.
Acrylic resist etching forms the basis of our studio etching practice. Rebecca Vincent etches on copperplate. I prefer to etch on aluminium so we teach both (but not at the same time). One of the students on this weekend's course had recently bought a Rochat etching press. So not only we were teaching him how to begin with line and tonal etching but we were also providing him with recipes and advice on what he needs to consider whilst he sets up his studio at home.
We have a number of students now who have been coming on a regular basis who have bought their own press but return to our courses as and when they need some more technical input to refine their practice.
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