gnupic@linuxhacker.org

Our method is slightly different:
- print final artwork on paper, laser printer preferred but inkjet is fine
for uncomplicated work
- produce a negative by printing onto photographic film in a darkroom
- print negative onto PCB under UV lights
- remove the unexposed riston with sodium carbonate (common, can get in a
supermarket)
- etch with ammonium persulphate
- remove the UV-hardened ristron with meth (not as fast as specialized
remover but leaving the board in meth for 5 minutes does the job)
- protect the copper from tarnishing using PCB laquer
Done.

We used to use  FeCl3 before my time and I have a rusted out brown sink to
remind me of it and it stains everything! I would not recommend it, the
persulphate method works a treat and it is clean. I wonder if anyone else
uses ammonium persulphate though and if I should change to sodium...

I have read the link to the yahoo group post that describes the process and
it is quite comprehensive. The author used FeCl3 though. Also he prints onto
transparency then onto positive pcb board while I print onto paper then onto
a negative and then onto a negative PCB board. My setup requires an extra
stage where I develop a negative film. However I tend to think that my
method is cheaper since I print on paper not transparencies and I print a
negative, requiring less toner. The photographics process is a hastle but it
only requires three chemicals (developer, stop and fixer). Although film is
probably as expensive as transparencies if not more. For my process I need
need negative PCB. I notice that there is a fair bit of talk in the thread
about positive PCB. I am not even sure I can get positive PCB where I am,
I've heard of it but never seen it. Is it any more expensive then the more
common negative variety. Does anyone have comparative pricings?

I am not even sure what 'pre-sensitized' means? Anyone care to give/point to
an explanation?

Eugene.