> dave wrote:
> <SNIP>
> The boards are positive photo from Maplins
> <SNIP>
Well in that case def. do not use lye.
Maplins might recomend it on the web page, but
the manufacturer recomends sodium silicate on
the package of the pre sensitized boards.
Sodium silicate is a lot more fogriving.
With lye if you have the temp. too high the
entire thing will just strip instantly.
If you under exposed positive resist then
EVERY thing should have stayed on.
As everyone has said 15s is probably too short.
Too short an exposure with positive and you
will get a completly covered board.