Subject: Etching Silver

From: [email-masked] (Marc Edgar)
Date: 9 Feb 1994 04:36:27 GMT

Greetings,

I am trying to make my girlfriend something nice for Valentine's
Day.  I had this bright idea to etch her monogram (actually 
her cypher) into 24 gauge sterling silver.  I am finding
that the photo-sensitizer, the same stuff used for transfering
artwork to PC boards (GC Positive is the brand name) does
not stick to the silver during the etch.  I am using concentrated nitric
acid as the etchant.  It looks like the photoresist is being desolved
by the acid.

Can anyone give any hints on surface preparation or other etchants to try?

Thanks a bunch,
Marc
[email-masked]

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From: [email-masked] (Clive Washington)
Date: Wed, 09 Feb 1994 11:40:46 +0000

In article <[email-masked]>, [email-masked] (Marc

> Can anyone give any hints on surface preparation or other etchants to try?
There are 2 possibilities:

1) you need to clean/key the surface, so give it a good going over with
fine
(600-800grit) wet/dry paper under flowing water.  Avoid oil like the
plague - if you can wipe with acetone and warm-air dry, so much the better.

2) Concentrated nitric acid is far too strong an etchant.  Bubble formation
will peel the resist, and you will lose the lot.  Also it may oxidize
the resist.  Try 10% acid at most.  Sulphuric/Hydrochloric acids will not
work.

It will take longer, of course, and you will find that it works best if you
keep an eye on it and use a fine paintbrush to dislodge bubbles as they
form.
Don't aim to go too deep.  As soon as you get any real depth you will start
to get lateral etching and loss of definition.  The photoresist is designed
for etching copper PCB's which only have a few thou of metal.

To etch copper, ferric chloride is often used, based on the redox reaction:

2Fe3+ + Cu -> 2Fe2+ + Cu2+

I don't think this will work for silver, however, having looked at the 
redox potentials.  You might try it with ferric nitrate (silver chloride
is insoluble).  The advantage, if it works, is that no gas is evolved to
peel the resist.

You'd better get a move on to finish by the 14th!

P.S. I never had much luck making presents for my SO.  Despite the
sweat-of-brow/master craftsman/uniqueness arguments, they seem to 
prefer it when you spend money.  It's quicker, too..

Clive W.

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From: [email-masked] (Bruce Johnson)
Date: Wed, 9 Feb 1994 13:41:17

In article <[email-masked]> [email-masked] (Marc Edgar) writes:
>From: [email-masked] (Marc Edgar)
>Subject: Etching Silver
>Date: 9 Feb 1994 04:36:27 GMT

>[email-masked]

   Well, when I was making jewelry (many years ago :( we etched silver and 
brass by cleaning the piece really well, then heating it slightly, and rubbing 
a chunk of beeswax on it.  The beeswax is quite resistant to the nitric we 
used (don't remember the concentration), and the only problem, as with all 
acid etching operations is the etchant undercutting the etched area.  
	Bruce Johnson
	The University of Arizona

	This place...have an OPINION????