Homebrew PCBs

--- In Homebrew_PCBs@yahoogroups.com, "Steve" <alienrelics@y...> 
wrote:
> Many years ago I made a bunch of boards using Datak Negative resist,
> sprayed it on with a pump sprayer. Do you mean you paint it on with
> those very soft fine foam makeup sponges?

Yes, I am.  They work well and seam to leave no fibre behind, like a 
tightly woven q-tip.  I can get good coverage with no waste and even 
pull any tiny dust particles to the side at least.

> 
> Get a red bulb rather than the yellow bug light. You don't need a 
very
> bright bulb ;') if you let your eyes become dark adjusted. I think I
> used a 15 or 25W when I was doing this.

Several people now have suggested this, may be part of the problem, 
it would make sense, since the pattern seems to only be there 
partially or not at all, leads me to believe that the whole board is 
getting exposed instead of just the parts I want.
> 
> Dry them in a bigger box. A small box will get full of fumes of the
> solvents and may never let the coating truly dry out. 

Also a good thought, I do have them in a small box now, I will try 
stepping up the size/oven idea.   

Also your xenon flash idea is good to.  I was thinking about trying 
to expose with my scanner, possibly a certain number of slow scans.  
But for right now I think I need to eliminate variables rather then 
add them.

Thanks,
ED