On Jun 5, 2013, at 1:47 PM, Perry Curling-Hope wrote:

> Fastest, cleanest etching 'cut' is accomplished with (Hydro) perchloric
> acid.
> This is dirt cheap and readily available, produced by mixing pool acid
> (HCl,, hydrochloric acid) with hydrogen peroxide, the so called '40 volum=
e'
> (12% H2O2, used as hair bleach and a disinfectant/cleaner which is
> available from a drug store) in appropriate proportions.
>=20
> Results have been so outstanding, I have not bothered with anything else.
> Perchloric acid is quite safe to work with at these dilutions.

I'm pretty sure, and I really hope, that this mixture does NOT produce "per=
chloric acid."
See http://www.sciencemadness.org/talk/viewthread.php?tid=3D14490

Perchloric acid is extremely nasty stuff (the strongest simple acid), prone=
 to forming metallic and organic peroxides in your fume-hood exhaust ducts,=
 causing eventual explosions.  You would NOT want to take a shortcut based =
on this message and pilfer some ACTUAL "perchloric acid" from your local un=
iversity lab, for example!

That doesn't mean that the HCl/H2O2 mixture isn't a good etchant.  Although=
, there are tradeoffs; a "good" etchant is usually considered one that diss=
olves copper pretty rapidly, while remaining fairly innocuous if you happen=
 to splash it on your countertop, your skin, etc.  I'm not sure that full-s=
trength HCl with peroxide meets the second part of that description.

I made up a batch of CuCl etchant, starting with HCl and H2O2 and dissolvin=
g scrap copper in it.  CuCl etchant  isn't bad, is infinitely rechargeable,=
 and is pretty cheap if you make it that way.  I used equal volumes of Pool=
-grade HCl and drugstore-variety H2O2 (3%) as the starting mix.
http://www.xertech.net/Tech/CuCl_ech.html

(and here is a lovely picture of a chunk of turkey, after it sat in 30% HCl=
 for 24 hours.  Nothing left but an interesting purple color!)
--=20
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