strange etch resistant behaviour

[Andy]

Has this ever happened to anyone?  After I etched my boards, I rinsed them off and to dry them, I put them under my lamp while I prepared my drill press.  When I went to get a board, the toner turned gray!  Weird.  I scratched off some of it to see if the copper was affected and it's ok.

This hasn't happened before but I haven't used my lamp to dry either.  Any thoughts?

[Mike Burgundy]

either there's still some active resist under/in the developed layer, or it's a heat thing (did the board get warm? this stuff reacts easily). As long as it's staying on during etching I wouldn't worry.