On 20 Oct 2008 12:51:07 -0400, you wrote:
>
>"lcdpublishing" <lcdpublishing@...> writes:
>
>> While developing, all the resist washed off.
>
>I agree this sounds like underexposure.
>
>If you don't have a step gauge, you can sort of calibrate your
>exposure by making a lot of small boards (like 1 in2) with a striped
>print on your film. Mark the back with exposure times in powers of
>two - 15s, 30s, 1m, 2m, 4m, 8m, 16m (more if needed). Expose each for
>the marked time and develop. Note the shortest time that exposes the
>clear areas, and the longest time that doesn't expose the covered
>areas, and pick a time between those. You don't have to etch these
>boards - just expose and develop, and inspect the film.
>
>If you have a step gauge, one exposure is all you need to calibrate.
>
Patience and thinking backwards can replace a step gauge while using a
single board.
Apply the resist, then mark the board into seven sections. Use a piece
of metal as a dark slide (we're pretty sure it won't pass UV 8:)).
Expose the whole board for 15s, cover the first segment.
Expose the remainder for another 15s (30s total), cover the first two
segments. Expose for another 30s (1m total), cover the first three
segments. Expose 1m (2m total), cover first four segments. Expose 2m
(4m total), cover first five segments. Expose 4m (8m total), cover the
first six segments. Expose the remaining segment for 8m (16m total).