I tried that for a while too - but i went back to buy pre-coated 
material. The copper needs to be cleaned very well to get a good coating 
and that is quite a bit of work.
The smell of the spray is quite strong and I am not so sure if it is 
even worse healthwise than the rest of the procedure. Finally if you do 
the spraying at home it is likely
to have some dust  fall onto the wet photoresist - and that may quite 
likely cause you a little defect on the pcb.

The main factor for me is not really the cost but the speed to get the 
whole process done. With the pre-coated material I just cut the size I 
need by routing with a small CNC-Desktop machine which can do the 
drilling from Excellon file as well. After drilling and routing I just 
need to peel off the protection film and ready to go....

>hi,
>
>I have one bottle negative photo-resistant praying
>liquid, call ER-71. It has been say, cheaper. Spraying it on
>clean copper clad board, after dry, I get photo-senstive
>pcb in negative. I don't have exposure equipement
>and never tried.
>
>It should be better and more convenient
>material for you.
>
>
>  
>

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