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Electo-etching brass


#1

I have good results when electro-etching copper.

However, I have a problem when I etching brass and requires that I
do extra polishing to get an attractive result.

Here is my electro-etch configuration:

A DC power source (rectifier)

Stainless steel cathode connected to the negative port of the
rectifier

Brass anode (object to be etched) connected to the positive terminal
of the rectifier.

An electrolyte solution of copper sulfate which is blue in color.

Here are the results of the etching process:

Copper is deposited on the stainless steel.

The electrolyte turns green.

The brass is coated with a substance that looks like deli mustard
and can not be simply washed off. This is the stuff that I polish
off. I 'm worried that the polishing is removing some of the raised
etched design.

Questions:

Is the coating simply an alloy of bass that has a high concentration
of zinc and tin because the copper has been removed?

Is there anything that can be done as part of the etching process
that will prevent or remove the coating? (add tin sulfate and zinc
sulfate to the copper sulfate electrolyte?)

As far as the green electrolyte is concerned, I pass it through a
stack of coffee filters which removes a very fine brownish “mud”.
Cleaning the electrolyte is less important.