Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

a 1% solution of NaOH (10 grams per liter) develops a board in less
than a minute -- I find it helpful to develop under a red darkroom
lamp (yes, I do BW developing as a sideline). I use 2 glass baking
trays one for the sodium hydroxide solution and one for water. The
red lamp is on all the time. I periodically switch on a "white" lamp
to examine the board.

Caution with Sodium Hydroxide -- over time the pellets (or granules)
will absorb water -- as you open and close the bottle in which they
are contained -- the moistened pellets will stick to your skin and
cause blistering -- so latex gloves are a good idea. I use filter
paper to weigh out the sodium hydroxide and find that over time the
little beads of NaOH will also stick to the filter paper -- not a
good idea to "flick" them off since they then go everywhere.

Drano is mostly NaOH, but there's a lot of impurities in it.