Homebrew PCBs

Any kind of a laquer or enamil works well.  One I like for covering
large areas is just plain old nail polish. I just use the clear (get
crazy with colors if you like :-) ), it comes in really handy as the
paint brush is already in the bottle. Great for touching up large
areas where the toner couldn't handle and there's some pinholes. Also
nice for covering edges of the board. It really resists toner well.
And it's cheap (if I procure it when my wifes not home, it can
actually be free - hehe). Just kidding, I actually always have several
bottles around as it's great for setting trimmers, locking screws,
marking boards, color coding almost anything (connectors, wires, ect),
and sealing traces. And it works great as etchant resist (at least in
the Ferric Chloride, I think it would work in anything) It's harder to
remove, but not much worse than the toner itself (Laquer Thinner or
TRPS strips it right off). It might work well for sealing the edges of
the contact film too or seams in tape. 
Phil (KA0HBG)

> How do I mask the bottom layer so the copper
> remained intact during contact with ferric chloride? 
> Lanny
>