Now prepare the negative photoresist film. It comes in a roll, so I need to cut the sheets of required size, 2 sheets per one brass sheet. The film has protective layers each side, so its 3-layer.
All operations with this film have to be carried out in darkness (no ultraviolet).
The next set of operations has to be done all at once.
First clean the brass sheet, both sides, wet. I used 600 grit and then 1000. Here I use brass sheet of 0.5mm thickness, 100x100mm.
We need a laminator machine, so turn it on, so that it's warmed up by the time we need it.
Remove the protective layer from one side only of the photoresist film and, working under a weak tap stream, attach the film to the brass sheet, so that the remaining protective layer is facing outwards, and the photosensitive layer is touching the metal. Water helps adjust the film position and ensure full adherence.
Do the same with the second film and attach it to the other side of the brass sheet.
Put the resulting sandwich between the 2 white cardboard sheets (to protect the photoresist) and pass it through the laminator, so that the films are baked onto the metal. I pass it twice.
As a result, I have a metal that is covered with photosensitive material on both sides and protective film layers are still there, both sides, outside.
The cardboard can be reused.
The most difficult thing for me was removing the protective layer from one side of the photoresist film. All in darkness of course. I found that doing it under water or making the film wet, helps.
Second and third photos are made in darkness
