Quick (but complete) notes on etching brass using photoresist.
- Clean brass with Brasso, and acetone. Dry and polish with lint free cloth.
- Spray with Electrolube PRP photo-resist, from side to side with light passes. Press and release can off of the work-piece to ensure an even coat. Dry for a few minutes with a hair-dryer.
- Print two copies of the design (mirrored) on to 90gsm tracing paper with as much density as your printer can muster - you might want to add a box around the image to sit a couple of mm outside the brass to help aligning the brass to the design.
- Overlay one copy above the other exactly and staple so the images align perfectly (this doubles the light resistivity of the toner).
- Place the tracing papers on the bed of a UV box (toner side up) and place the brass on top of it exactly where the etch is to go.
- Develop with Sodium Hydroxide (1 teaspoon of the powder to 1 litre at around 25C) for around a minute, agitating the solution until the developers rises off. Rinse.
- Heat enough ferric chloride for the etch in a microwave, or make up crystals to 50-60C. Etch for 1-2 hours depending of your required depth of etch. Agitate occasionally.
- Rinse and polish as needed. 1500 grit paper may be a good start.
