90% Isopropyl Alcohol for Cleaning Coins

That Stonybrook article has been linked a thousand times times in discussions of acetone, and I've debunked it a thousand times. You have to work hard to get enough light and enough humidity into the picture to force that reaction - I've done it successfully, it takes hours - and if your conservation technique is that sloppy you deserve what you get. It is simply not a factor for anyone capable of using acetone without splashing it all over themselves.

With that said, knowledge is a process, not a place. Even though I know acetone cannot affect metals except only copper, and only under those extreme outlying circumstances - I know this for the same reason I know the Sun is bright, the laws of physics dictate it - I'm not discounting what Numismat is saying. He sees what he sees, this isn't his first time on the merry-go-round.

Is it because the acetone only partially removed what's causing the color? Was there a layer of lacquer or something disabling the thin-film reflection angles and hiding existing toning? I dunno; all I know is that acetone couldn't be a part of the reaction.

 

Log in or Sign up to hide this ad.

I tried to get acetone to react with copper both inside a house and outside in sunlight (for the UV) and nothing happened.

 

I ended up mixing it with water to get there. Sufficient humidity is the problem.

 

I thought no cleaning on coins..... No exceptions!?

 

This is like telling teens it is illegal to drive bare-footed.

 

Eventually, try to get some "medical grade" not Home Depot stuff. A beauty supply store sells pretty good stuff for your needs.

 

Only thing?? I heard that Acetone, Goo Gone, and many orange based (citrus?) cleaners do a much faster job.

 

Faster - Better - Cheaper...pick any two. Seriously, when you use anything othjer than a pure solvent - no matter water, acetone, xylene, toluene, isopropyl alcohol, etc. you are asking for trouble.

 

That's a list where "one of these things is not like the other." Acetone is a very different animal than a concoction of cleaning chemicals and acids.

 

This bluish color is typical of acetone color on a copper coin that has been conserved using _________. If you were to put Coin Care or "nose grease" on this coin it would return to brown. In the old days, TPGS did not like this color on copper...times have changed.

 

Of course the coin might have toned after the certification. Can't see them calling this "BN".

 

It is brown...no red. As I said, a little thumbing and you'll get a nice. lustrous brown coin. Try it - but use care on a Q-tip, not thumbing. Then turn it back again with acetone.

 

I have used acetone on coins with tape glue on them and they were still sticky. The other things I would not use. 90% alcohol works without any of the significant affects to the coin using random stuff on them.

 

Of course they were, there was still sticky residue left on the coin! Remember to use a new Q-tip with fresh acetone each time you apply the product. When I have a batch with tape, I lay them flat an put Goo Gone on their surface...just enough to cover the coin and flow out to the rim w/no spill-over. After a while, I remove the glue w/ either more goo or acetone. You can tell when the surface is done. No raised/sticky residue.

 

I've had good results with glue/tape residue just putting the coins in boiling distilled water for a few minutes.

 

"Acetone color"? More likely due to using MS70. Acetone will NOT react with metal, plain and simple. I've used acetone on THOUSANDS of copper coins and it has never turned any of my coins. One single exception is a copper token from the 60's that was covered with a semi-sticky, transparent residue. When I used acetone on it a haze formed (probably dehydration of the non-polar-type residue). A soak in xylene removed the residue and the haze.

 

They call toned copper BN at all the TPG's.

 

I wish people would stop linking to that ridiculous article. It appears to have been done by undergraduate students. It is so full of unsound scientific testing protocols and detail it makes me ill. Most notably, it doesn't mention how they protected the test vessels from air. The vessels should have blanketed with nitrogen and sealed. Apparently, it didn't occur to these kids that solutions will absorb contaminants from the air.

 

Bingo...you filled in the _____________.

 

Thanks for info, I cannot wait to read it!!!