High concentrations of H2O2 result in VERY exothermic reactions. Etching
takes place in seconds. Lots of heat. Lots of acrid fumes. Do outside or
with a good hood. Have water available to put your board in to stop the
etching. I did a lot with those high mixtures but decided it wasn't worth
the problems and went back to 3% peroxide. I usually use a sponge with a
small quantity of etchant. Takes a minute or two but is very controllable
and uses only a fraction of the volume, making disposal much easier. I
don't make a lot of boards, so it's not worth keeping vats of chemicals
around.
Mark
At 12:32 PM 3/23/2019, you wrote:
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Noted.
Thanks,
Dave
On 3/22/2019 7:40 PM, Harvey White wrote:
On Fri, 22 Mar 2019 20:31:31
-0400, you wrote:
I found Sally Beauty Supply to
be a good source for H2O2. I recall the
"volume" rating is a bit more than 3x the concentration, so
"30 Volume"
H2O2 is 10% concentration.
Do be careful, since the drugstore
concentration is far less than the
various products available in beauty supply stores.
I'd think that the best use is as follows:
1) build the etchant with drugstore H2O2 and HCL.
2) when desired, top up the mixture with beauty supply H2O2, but in
far less quantity than needed for the initial mixture.
YMMV
Harvey
