Solar-plate etching, or photopolymer etching, is a process by which one takes a photograph printed on clear transparency and exposes it to a plate that has been coated with a light-sensitive emulsion.
I lay the printed transparency on top of the plate, expose it to the sun, stop the process in a water bath, and after the plate hardens, I ink it and print it on a traditional intaglio or etching press.
Some have called this process photogravure, but it isn’t a similar process, nor are the materials the same. You could say that the results are similar – a plate is inked and then hand printed on the press, typically on cotton paper or mulberry paper (or other fibers and blends).
However, photogravure is a more involved process using gelatin on a copper plate (after exposing the photo transparency on the plate). Then the plate is dipped into a succession of acid etching baths. Depending on the depth of the gelation and time in the acid bath, an extremely wide tonal range can be achieved and you can create an extremely detailed print.
With photopolymer etching the process includes just one exposure to the sun (or a UV unit) and the materials are non-toxic.
The key to photopolymer etching is the photo-production (using Photoshop), making sure your tones are within the optimal range considering the sensitivity of the emulsion, and this will produce a detailed image, even if the tones are limited. However, the photopolymer emulsion is very soft after exposing it, so care is needed when stopping the plate in the water bath. Some plates simply don’t make it past this point!
And with photopolymer etching there are more serendipitous occurrences due to the delicate nature of the emulsion, and there is an ethereal quality to the work –– and that for me is what I’m aiming for.