The finishing.com Hotline -- Serious Education ... plus the most fun you can have in metal finishing
What type of Nitric Acid dissolves silver?
January 13, 2009
Q. Fifty years ago I watched my Dad etch sterling (925) and coin (90%) silver using Nitric Acid that he bought at the local drug store. He made an example of what this acid would do to me if I should ever get into it by dissolving a silver dime in it. Now that I have retired I have decided to try my hand at etching silver items. I bought a bottle of 96.9 pure Nitric Acid but it will not dissolve silver. So I bought a bottle of 99.5 white fuming nitric acid hoping this wrought do the job, it only turns silver coins black. What type of nitric acid would dissolve a silver coin and where can I find it,
hobbyist - Scott City, Missouri
February 16, 2009
A. Any concentration of nitric acid would dissolve silver. What you got most probably is not nitric acid.
Nitric acid max concentration is around 67%.
Good luck .
aircraft maintenance - Al Ain, Abu Dhabi, United Arab Emirates
February 16, 2009
A. Nitric acid is one of those unusual acids where stronger is not better. It becomes an oxidizer rather than a stripper. Try a 50-50 mixture with distilled water.James Watts
- Navarre, Florida
June 25, 2010
A. I'm using 70% Nitric Acid to dissolve Silver (and copper) out of CPU's before further refining. Dropping the silver out of concentration with table salt. It works best when left for 48 hours (although the reaction can be quite violent at first). However, my question is: Can I reduce the concentration of Nitric acid used to dissolve the copper/ silver as it would reduce overheads on the extraction process. I'm currently shredding the finds to increase the overall density (reduce void spaces), so that I can reduce the volume of Nitric acid that I have to use.Richard Johnson
- Cambridge, England
April 13, 2015
A. Hi, I only just started refining silver yesterday and I use a 50/50 mix of de-ionised or distilled water to nitric acid. My nitric is 60% strength and it dissolved 3 oz of silver in about an hour In to silver nitrate form. I then watered down the solution again to a further 50/50 and then filtered it through a coffee filter and then dropped a length of copper pipe in and watched my pure silver powder drop out of solution.. Just drying it now and waiting to melt it in to a bar. It's true about the strength, if it's too strong it will create a protective layer around your silver that stops it from dissolving. So try a 50/50 mix with water and see if it works.. If not you may well have bought the wrong acid..Paul liff
- luton, england