We use 50% ammonium hydroxide and 50% 3% Hydrogen
Peroxide.  This lasts about 2 - 3 hours after mixing.

The amount of time needed to properly etch mounts will
vary from lab to lab.  It depends upon how much smearing
of copper is present and the person who etches.  Some
people press harder than others.  So you must experiment
to determine time to get good lines of demarcation and
grain structure (without over or  under etching)


The concentrated 30% poses a safety problem and had no
stabalizers in it.  The original formula that says use 10mls
water and 3 drops of 30% would yield about 10 mls of 3%.
We use medicinal grade Hydrogen peroxide - 30% and I buy it in
500 ml bottles.  I also buy my ammonium hydroxide in 500
ml bottles.  They both run out at the same time and keep
their individual strengths.

Susan Mansilla
Technical Director

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