ACID ETCH

[ROBERT #37544]

Help please! I keep hearing about "raising" old number stampings with some sort of acid etch method. Can someone explain exactly how this is done? Thanks in advance, Robert, Cincinnati

[Joe L.]

Re: ACID ETCH

Robert-----

What you inquire about is, basically, a forensic technique. It's primary use is to determine what characters may have been previously stamped into a metal piece USUALLY for evidentiary reasons in a criminal case. However, it can be used for other purposes. While this technique can be used to determine what numbers were once stamped into metal, IT WILL NOT permanently restore the numbers/characters; it will simply allow one to determine what stamping was previously present. Also, it's not always successful and, even less often, completely successful.

[Ken Edmunds]

Re: ACID ETCH

I used to use a product called Fryes Reagent to bring up numbers on steel. Keep rubbing it on the steel until the shadow appears.

[Frank C.]

Re: ACID ETCH

Robert....IIRC my father who worked auto theft in a large city told me they used hydrochloric acid to raise #'s that had been ground off by crooks. Hope this helps.

[ROBERT #37544]

Re: ACID ETCH

Thanks very much folks. I have found a Metalllography Forum on the web that has loads of information on Fry's Reagent, and many other etching solutions used to "color" the micrograin in metals, or as some say, to reveal the "plastic deformation" in the metal- sometimes used in forensic metallurgy.

A much cited book apparently contain many different formulas for etching solutions- Metallography Principles and Practice by George VanderVoort, McGraw-Hill, 1984, ISBN 0-07-066970-8.

Also, one can try a Google search for "Fry's reagent in forensic metallurgy".

Thanks again for the tips,
Robert.