Homebrew PCBs

Gary,

You might want to avoid etching anything but PCB
in your main etch bath.  Make up a seperate little tank
for playing with brass or anything else.

Brass is 30% zinc on average; and zinc is highly reactive.
It makes a great catalyst for decomposing H2O2.  I can
imagine many different baths that it wouldn't be good for...<g>

Also, wasn't the "original" formula for this etch-bath
specified for -2- percent H2O2 ??

Your out of control exothermic reaction sounds like too
much H2O2 to me...

good luck, and please report back here how you solve
each issue!
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