What safely removes lacquer from a half cent?
DMWJR
Posts: 6,045 ✭✭✭✭✭
Looks like it has been there a long time. It's only on the reverse, but the coin would look more natural and not too glossy if I could safely remove it. It's a brown coin - no red.
Doug
0
Comments
Perhaps some lacquer thinner?
There are different types of lacquer. I wouldn't start with Insider2's suggestion. Having worked as an analytical chemist in both the paint & chemical distribution businesses, I can offer some comments.
If the lacquer is old, it's probably nitrocellulose. I reviewed some of the discussions in guitar websites and I can vouch for some of their comments. The safest solvents for nitrocellulose lacquers would be either VM&P naphtha or mineral spirits. Lacquer thinner or paint thinner may have some cheaper unknown components that you wouldn't want to introduce - this I know to be true.
If neither of those works, I'd go with toluene or xylene. After that, it's anybody's guess. I agree in general that polar solvents such as ketones or alcohols (acetone, MEK, isopropanol, ethanol) might work (depending on the type of lacquer), but I'd be more cautious about using them, especially on copper.
I knew it would happen.
Thank you @jmski52 ! I was leery about using any old thinner because it is copper and more importantly, I don't have experience with this. The coin is not a super valuable coin, but still I don't want to leave it worse than I found it.
Methyl ethyl ketone will melt plastics... I've used this in the lab to bond plastics together, but be careful here. MEK is quite volatile and should be used in a chemical fume hood.
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Sorry, I was making a veiled joke. I have many of the chemicals mentioned by the chemist in the post above.
Nevertheless, I would start with the lacquer thinner. What is not said anywhere is that SOME professionals (I only know of one) TEST a chemical on a coin UNDER A STEREO MICROSCOPE with the point of a wood sliver BEFORE starting any conservation. That is OFTEN the difference between the "ham-fisted" off-color, blotch -job crap that a bunch of folks get paid for and a bit of nice "work" that goes undetected.
@DMWJR said: "I don't have experience with this."
That is the EXACT REASON you should not touch the coin UNTIL you get some. Practice makes perfect - except for the occasional, unexpected "BLOW-UPS" that can happen to anyone.
My own experience has been acetone as a first step. The coin below was soaked in neptha-thinner and then acetone and then distilled water. I purchased this coin with disclosed lacquer here on the BST. I was concerned about wrecking the coin as acetone would not cut it at all even soaking for a week , the neptha-thinner worked fast. The coin has remained stable the last 2 years. This is a general comment and not in response to any other comments.
Please make sure you use in a well ventilated area. Some of these solvents are flammable and not very good for your health.
Good luck.
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Please make sure you use in a well ventilated area. Some of these solvents are flammable and not very good for your health.
All of these solvents can be absorbed through your skin and simply by breathing, which is exactly why you should keep exposure to a minimum. They all have some degree of toxicity and are all routed through the liver. And flammability requires that you do not use them around any open flames or any ignition source. If you are not familiar with a chemical and know how to handle it, you should not be using it.
I knew it would happen.
Thank you. I do know how to handle chemicals, just not what is best on 200 yo copper to remove lacquer without causing a negative reaction with the copper. @SamByrd that coin looks good. Did you get it graded? I have acetone, naphtha, xylene, and mineral spirits on hand. I think I will try the naphtha first. I'll try to see If I can do before and after shots.
I have not had the coin graded. I think it would come back as genuine its 50/50. I had trouble finding a nice half cent of the era that was not high dollar so it will remain a free range coin in an album.
You may have to use a thin coat of mineral oil to re-stabilize the copper as any chemical used will effect the copper to some degree.
The information by @jmski52 is very good.... I recommend you take all precautions though. We worked with these solvents in companies I was part of, and always had trained individuals handling them. At one point we eliminated MEK from factory use...just too dangerous. Cheers, RickO
You know what I am going to say Doug - acetone. And my non chemical handling based experience is that the others can remove more than the lacquer. Heck, Xylene is like brake cleaning fluid and real nasty stuff.
WS
You can use up a quart of acetone on some coins with tape residue and the ONLY RESULT will be that you used up all the acetone and will need to buy more to continue on with this ridiculous attempt. READ THE THREAD. Acetone and most other chemicals (I haven't tried Naptha recently) don't work in a timely manner or they don't work at ALL.
Perhaps, the OP should try the experiment I suggested.
Paint strippers containing MEK are being removed from the market soon due to cancer risks from use in enclosed areas.
Insider2 do you really need to try to discredit everyone who doesn’t make the same suggestion as you?
I do agree with you Bob. I had a doctored IHC and had to let it soak for a week in Xylene to get the junk off. Came back MS65 from PCGS. Was previously in an NGC 66 holder until I cracked it and PCGS sent it back in a body bag. Years later it became more apparent what was wrong with it. That’s when it got the treatment. I tried Acetone first, but after almost a month, nothing.
@DMWJR said: "Insider2 do you really need to try to discredit everyone who doesn’t make the same suggestion as you?
I challenge you to answer this question. I'll take any # that is close.
That said, this is a FACT: While acetone is my first go-to chemical, in my experience (I've been professionally cleaning coins for collectors/dealers since 1972 at ANACS - bet you and others had no idea we did that
back then), it does not work very well or very fast on many residues and adhesives. Additionally, it has absolutely no effect on some types of old tape. I have also proven this for myself.
Therefore, I should appreciate it if you and anyone else so inclined don't consider the things I post as either an attack, an attempt to discredit, self-aggrandizement, or anything else EXCEPT an attempt to share my opinions based on experimentation/results over the years.
There are some posters/posts here that I look forward to reading. Their comments based on experience is valuable. For example:
@jmski52 said: "There are different types of lacquer. I wouldn't start with Insider2's suggestion. Having worked as an analytical chemist in both the paint & chemical distribution businesses, I can offer some comments.
If the lacquer is old, it's probably nitrocellulose. I reviewed some of the discussions in guitar websites and I can vouch for some of their comments. The safest solvents for nitrocellulose lacquers would be either VM&P naphtha or mineral spirits. Lacquer thinner or paint thinner may have some cheaper unknown components that you wouldn't want to introduce - this I know to be true.
If neither of those works, I'd go with toluene or xylene. After that, it's anybody's guess. I agree in general that polar solvents such as ketones or alcohols (acetone, MEK, isopropanol, ethanol) might work (depending on the type of lacquer), but I'd be more cautious about using them, especially on copper.
Please make sure you use in a well-ventilated area. Some of these solvents are flammable and not very good for your health.
Please note that I gave his post a "Like."
As for your post, I should give you a "Dislike very much" but that option does not exist.
PS As I edited this post, I just saw that acetone did not work for you either. Welcome to the "club."
My grandmother used to buy large containers of Naphtha to dry clean her clothes. Unfortunately it is extremely flammable and can be set off easily by a static discharge resulting in ........ well you know
Yes, all solvents are best used out of doors.
bob
Good advice. My uncle worked around industrial chemicals much of his life after the age of thirty-five. After he retired he had nerve problems that were attributed to his job.
In another forum, they have been discussing acetone and many chemists argued that it is not as dangerous to handle as I always thought. What do the chemists say here?
Acetone is hazardous in that it is more flammable than gasoline and in that it is a ketone, which is not good for the liver. Acetone will de-fat your fingers, but it does evaporate quickly. Not as dangerous? Handle it as you would handle gasoline, and don't make a point of being heavily exposed to liquid or vapor. Wear gloves and work in a fume hood or a well-ventilated area, away from ignition sources. Any other approach is simply risky.
Acetone and MEK are both oxygenated solvents and have different solubilities on different types of resins than do aliphatics and aromatics. Alcohols are also oxygenated solvents with different solubilities on different types of resins as well. Acetone, MEK, Ethyl Alcohol and Isopropyl Alcohol are usually supplied as pure compounds (except for reagent grade Ethyl Alcohol which is denatured with small amounts of other solvents to keep idiots from drinking it).
VM&P Naptha is indeed very flammable (gasoline contains some of the same components as Naphtha). Mineral Spirits is a relative of VM&P Naptha - only with a higher boiling range (and only a little less flammable). The solubilities are similar and indeed both are mixtures of aliphatic hydrocarbons, rather than single compounds.
Toluene and Xylene are also components in gasoline, but they are aromatic (contain a "benzene ring") whereas VM&P Naptha and Mineral Spirits are aliphatic (single bonds only), so the solubility characteristics are certainly different. Toluene and Xylene are pure compounds and not mixtures, so they will vary in performance less than a mixture.
These 3 classes of solvents - oxygenated solvents, aliphatic solvents and aromatic solvents - all have their place and in many cases the type of resin determines which type of solvent will dissolve the resin most effectively.
There are other classes of solvents, including naphthalenes, chlorinated solvents, fluorinated solvents, and hybrids of these.
It's widely accepted that water is the most universal solvent, and in many cases a higher temperature increases the solubility of a material, which is why the boiling water approach isn't a bad move, depending on the resin or contaminant. In some cases, heat might also cause the residue to harden even more by cross-linking and this will make the residue more impossible to deal with. So, it's sometimes a crapshoot.
Perhaps the best approach would be to analyze the residue and get an idea of what it might be, before exposing the coin to any type of treatment, but even then you need to know in advance what to analyze for.
I knew it would happen.
@jmski52
This is exactly what I wished for in my discussion asking to share info from each member's profession to aid numismatists. THANKS!
May I have permission to copy and post it into that discussion?