Use of DMSO on Coated Lincoln Coins

http://www.cointalk.com/t60979/

If you read the thread above, you will note the difficulty that Boss had trying to remove a "lacquer" type of coating from a couple of high end Lincolns he had, namely a 1911-d, and a 1916-S. Eventually the thread got to where maybe DMSO might be a possibility, but needed proper handling. I PM-ed Boss and asked if I could see the coins, and he mailed them to me, with permission to try what I felt might work.

If you look at the previous thread above, you can see the original photos he had taken.

When the coins arrived, I did take the following photos that show the extent of the lacquer. Even though he had used acetone and xylene for extended periods of time, I still tried acetone for 1 hr. looking for any residue, and there was none, so he was correct in it being ineffective.
I then took these photos of what I now suspected was an acrylic mix.


here is the microscopic photo of the acrylic pooling around the letters on the 16-S







Before Boss's coins had arrived, I had found some "sacrificial wheaties" with the same level and type of patina, and subjected them to long periods in DMSO, to see if any deleterious change occurred. Even with 24 hrs, after removing, I tried rubbing, plastic scrubbers, toothbrushes, to see if the DMSO had softened the patina that I could damage it. Obviously I wanted no effect, and except for the slight scratches, the patina didn't change level or color, so I asked his permission to try DMSO on the coins.

After several changes of DMSO over a 4 hr period, I noticed some residue on the glass containers used, and even took this photo of a
glob that stuck on the date after the DMSO dissolved most of it.


But it just flicked off with a sable brush wet with DMSO. Proof for sure there was something on the coin and had been partially removed.




I finally did not get any more residue, but there was still some "shine" on the coin, and I suspect it is acrylic that is attached so firmly to the metal that physical action would have to be used to remove, and I wasn't going to do that. maybe if it was my coin , I might roll a q-tip over the surface, but not with someone else's. Scratches and wear lines were more apparent after the lacquer was removed, and I assume were the primary reason it was put there in the first place. Here is a photo of the 2 coins as I got ready to return them to Boss. I wished I had taken a photo of the reverses also, but I didn't.



and viewed at a light angle to show sheen off obv.


I think the 1911-D will tone up nicely and even with the visible scratch and tiny hairlines will be a nice coin. It appears about AU55 under the scope. The acrylic did hide a lot of problems and probably why done instead of preservation purposes. The 1916-S is AU-58/MS and still has some glossy parts where the acrylic and maybe the dellers interacted a little, but it shouldn't have, so I don't know what made the bluish shiny spots of the rev. of the 16-S. After I mailed them to Boss, I thought maybe the bluish spots is fractured acrylic, producing a fresnel effect, but I am just guessing.


Hope I didn't screw anything up, as I think they look more natural now, but it will take some time to see. The thin film of acrylic should eventually degrade. I think they are nice coins myself.

DMSO seems to be benign on the patina of copper coins. But I would recommend the clinical/vet type which is 99.9% pure. It is water and alcohol soluble, and I used 91% isopropyl alcohol from Walmart to rinse the DMSO off of the coins and then a final rinse with acetone.



As is the case with all chemical treatment, one should do trials before attempting on special coins. Also the acrylic seems to do a very good job of hiding scratches and tiny pits, so the resulting coin may have more blemishes than previously visible. I thank Boss for giving me the chance to test this procedure.


Jim

 

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I have more photos, but this knew method of posting off web pages verses my hard drive so I don't have tiny, winy photos is time consuming.
I am very, very please with Jim's treatment. This worked very clearly to me. I will post more photos and find the orginal 1916 S post as well.






From Lincolns 83109">

 

1916 S post DMSO:



From Lincolns 83109">

From Lincolns 83109">



1911 D post DMSO:

 

Hmmm...I knew it couldn't be done.

 

Great post Jim!!!

 

Actually the sheen was there on the 16-S before the DMSO treatment, just that the DMSO didn't remove it. Doug's remark about it taking a while to be sure reminds me I had better get the "Verdigone experiment" coins out and rephotograph to show how they have come along. I really don't expect anything dire to come from the DMSO, the chemical makeup would indicate non-reactivity with metals, and the use of high grade DMSO removes much of the possiblilty, as well as using their solubility in alcohol, and acetone removal of the alcohol and drying action. But, assumptions in science are bad, so the coins I practiced on, will go into storage and be re-examined in the future.

Photos can't tell the whole story. I had these coins in hand before and after the DMSO, and they aren't my coins, but I could tell a big difference in the surfaces, with them looking more normal after the removal of the coating. Before in my searches for Spock on his lacquered/shellac coins, I couldn't find any mention of removal of the more modern acrylic mixes. Many solvents can dilute them before application, but once they harden, no mention other than physical abuse could remove it.

Also, I was looking for lacquered coins on ebay to try on my own before Boss so kindly let me work on his.

Tom has always been asking for Open and implicit information on chemical interaction, so I hope this encourages scientific discussion. Hopefully, although I am certain not all, anyone wanting to do this should read the whole procedures carefully

Jim

 

Your Effort

Gee, Mr Wizzard,

Glad you have the patience to do all this stuff.

Even happier you document it for all of us that follow.:high5:

Really Keep up the pursuit of :goofer:

 

I am so grateful Jim, was willing to do this. The coins look much better in hand. Particularly the 1916 S. Jim had PM'd me, if I recall, about trying to get the rest of with UV light. I did notice the spot on the reverse of 1916 S below ME in AMERICA.
For Jim- do you advise sitting in window sill in like an air-tite, or flip, etc.? If it breaks down more than, I assume to remove with alcohol and acetone as you described. Should I do more DMSO? Remind me, and for others, why did you stop without removing all the acrylic? Once again, props to Jim. He's the man. :high5::high5::high5:

 

Hey Desertgem, what are you using to take those super-close-up photos?

 

Tom has always been asking for Open and implicit information on chemical interaction, so I hope this encourages scientific discussion. Hopefully, although I am certain not all, anyone wanting to do this should read the whole procedures carefully

Yes Sir...thank you Jim. Honest open conversation is indeed my hope. I certainly like frank discussion rather than strangely skewed opinions mixed in with some facts. It makes things very confusing. Hats off to you Sir and keep it coming. (I'm deep in research for that DMSO was it?). I love people who are willing to present alternative points of view. The old...never..dont...shouldnt...cant.. gets really old.

 

You still don't know that it has been done. Nobody ever questioned whether the stuff could be removed Tom - prety much anything can be removed. The question is, can it be removed without altering the coin ? And we don't know that yet. And we won't know it for some months, maybe even a year. For after a coin undergoes chemicals - things change over time.

Let's just say I'm happy Jim thinks a bit more "progressively"..right..wrong or indifferent..that's the kind of attitude that leads to new and better ideas. Cheers!

 

Thanks Tom, I am certainly not against experimentation and documentation. My biggest problem concerning this experiment is that I have no way of knowing what the substance actually was. I assumed acrylic after talking to a chemist here who worked in the plastics industry, but the DMSO did remove some of it. Boss, I didn't go farther with the DMSO, because I felt I would have needed to use q-tips or something and physically rub off the remaining, and I didn't want to add any more hairlines or damage the surface on your coin. The sheen part would have been where I probably would have started that. Boss, this is where I would let the coin sit for at least several months and see what happens. Wouldn't hurt to rinse occasionally in alcohol and then acetone, and let dry to see if any more is coming off. If you want to return them after the first of the year, I would look at them again and photograph to record.As far as the sunlight, as long as the window glass in not low UV glass, it should work.

For the photos, I take close ups with my canon A-570IS through the eyepiece of my old surplus B & L stereozoom microscope 7X-30X. The camera is funny as it recognizes the "faces" on coins and focuses on them, except it does have trouble with the coins with indian head dresses

To All, this is not a DIY article. There is no certainty that your lacquer is the same kind. Try alcohol or acetone first. Practice on sacrificial coins. Only use pure grade DMSO. Do not use any physical action without understanding the risk.

Jim

 

Thanks Jim. Great experiment and what a wonderful way this sit has helped another fellow coin collector.

 

Thanks guys nice thread!

 

Wow, great post Jim! Filled in the wait for my lunch very well.
Consider it bookmarked, with Many more of your threads. Great to see members working together like this.
Thumbs up to both of you!

 

Jim, another great experiment and documentation effort. Many of the CT crown can't get around to doing all these experiments, so your efforts are welcomed and sincerely appreciated. Please, keep it up and show how these coins change over time.

Bruce

 

Jim, excellent job once again! I just now found this thread, it's been hiding on me or perhaps I've been too busy with my book.

Did you consider trying sonication in DMSO? It may give you the physical action you're looking for without actually having to rub the surface.

 

If you are talking about an ultrasonic cleaner, I have one, even with a plastic tray, but I have not been able to find a way to hold the coin under in a way that they weren't vibrating against something.I suspect that since the coin vibrates when free, the "junk" on it vibrates along with it and doesn't separate. I have been looking for a "sonic wand" that looks like a small waterpik , but sends out sonic waves from a small piezo crystal, and can be submerged. That way I could hold a coin under by the edge and point the sound where I wanted it. Maybe I could funnel a dog "caller" through some syringe tubing and needle.

Jim

 

I wonder if you could use sound waves to make the paint lift off the surface of the coin, with out damaging the coin. Just a thought. -O)