Homebrew PCBs

I have been using tracing paper (Vellum?) and a laser printer to produce 
transparencies for photoresist. I have some good results, but the large 
dark areas tend to be less than opaque having a speckled appearance 
which tends to be reproduced on the copper. I was reading about some 
spray cans which supposedly darkens the toner pattern (Toner Aide and 
Casey's toner darkener). Unfortunately I can't find a supplier in New 
Zealand and if I could it would probably be around $30-$40 a can. 
However they appear (from their MSDS sheets) to be a mixture of solvents 
sprayed from a can so I mixed some Acetone and Ethyl Acetate and sprayed 
this on the transparency from a small mister spray bottle I had. It 
worked, although the vellum curled up a little.

You might try Krylon Crystal Clear Acrylic Coating 1303. It claims to be UV invisable, and it does darken the print up, but, I'm not sure it is worth the extra step. I've had better luck with just doing 2 prints on heavy tracing paper 90#, carefully aligning them both on a light table, and using the the "double" for the mask. This works well...the vellum or heavy tracing paper is nearly UV invisable.

> Bitsy Wrote:

> I have read that Toner Darkener is basically a matt clear

> acrylic, or even hair spray, from this thread...
> <SNIP>

I have some of the toner darkening stuff. It is all solvent

as it leaves no residue after spraying.

It definitly works at darkening ground planes etc.

Still not as dark as the inkjet though.