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On 06/18/2017 10:37 AM, karl AT aspodata DOT se wrote:
> I usually use natriumperoxidisulfate for etching, would there be any
> advantage to use H2O2/HCl instead ?

The advantage I like for middle of the road 10 mils line and space, (not attempting 6 or 4 mils),
is that the CuCl2 etchant is easily neutralized so it is not an environment problem.
When you add NaOH to make it neutral, the copper precipitates out as oxide dust
that is heavy, so easy to separate out of the bottom of a pan.  The water is slightly salty
with NaCl after neutralizing, but OK to pour on the ground without killing plants.

I've not found any recycler that buys copper oxide dust, but we have a household disposal
service by the city that will accept things as long as they are not industrial output.


It can be turned back to copper by heating in a retort with charcoal and no oxygen...
but I gave that kind of gas fired foundry work up in '02.  Maybe later with a microwave
absorbing crucible in a 7X microwave, as in the "microwave steel" method...

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