A friend of mine just brought in his coin collection to show me. He had sorted and stored the coins in the A5 plastic coin slot sheets that he bought from the SA mint.
I noticed that most of them (excluding the silver coins) were tinged with a bright green, sticky residue, which I assume is some sort of reaction to the plastic.
What would be the best way to try to recover these coins? Perhaps a long water soak and dry? Can anyone give me advice.
I had the same problem with coins in South African and German albums made in 1980s and 1990s. Acetone is better than soap here. Put on gloves, wash coins in acetone bath. Mind that acetone should be in a glass bowl (not plastic!). Better use tweezers with rubber ends when taking coins out of acetone. Then rinse coins in water and dry them patting between two soft cloths, if coins are high grade. Worn coins you can safely rub with soft cloth. It's warm in South Africa now, so do this outdoors, since acetone is toxic and evaporates quickly. No open fire near acetone!
I collect coins and tokens which circulated in Africa from 18th century to 2000. I sell about 7000 illustrated world coins from http://www.avscoins.com.
If it is PVC damage then you are going to want to use acetone instead of soap. Acetone is an organic solvent that will not hurt the coins (it is impossible for it to do anything to metal, but see note about getting pure acetone). The only concern is that when you take gunk off it may have toned differently under the gunk. I've put hundreds of copper, nickel and silver coins though acetone with no problems. Stubbornly gunky ones I have had to let soak for months. I wouldn't rub the coins either if they are high grade, it will leave small marks on them. (Also, this advice only applies to modern coins, I know nothing about ancient coins. Also, don't put a painted coin in acetone, or a printed one, etc. like some of the modern Canadian ones, it will take it all off).
1. Make sure you use pure acetone, fingernail polish remover is not usually pure. You can pick up a can at Walmart for $5.00 or so.
2. Read the warning, don't use it around open flames and don't huff it, etc.
3. Get a glass jar that can close and cut out a cotton cloth to fit on the bottom (so you don't accidentally scratch the coins).
5. Pour in some acetone and let them soak for a while. Swish the acetone around every once in a while to help work off the PVC gunk. I don't use gloves because the acetone will eat away any plastic glove and just get the plastic gunk on your coins. It will make your hands a little white where you touch it and strip the oils away but as long as you aren't bathing in it or drinking it you will be fine. (Your body produces acetone naturally anyway).
6. For really stubborn patches you can gently work it off with a q-tip swab.
7. When done let the coins air dry or gently pat them dry. Some people recommend washing in water but I don't because the acetone will evaporate way if allowed to dry, and putting water on them just introduces more contaminates.
Acetone would be you best bet. Soap and water would damage any copper coins if there are any. The acetone however, might have an unpredictable effect on copper but none on silver. And please do not rub you coins with your fingers, not only might you leave fingerprints you may damage them.
Quote: axchouAcetone would be you best bet. Soap and water would damage any copper coins if there are any. The acetone however, might have an unpredictable effect on copper but none on silver. And please do not rub you coins with your fingers, not only might you leave fingerprints you may damage them.
Don't worry, acetone will not hurt copper, and I doubt rubbing with your fingers will hurt ether. metal is tough, that's why we use it for coins.
Glad to see you back on the forum Janine
Taking a break from swapping for a while, but still interested in pre 1799 Spanish coins, I will make time for that!
Thank you to everyone who gave advice on this! I did try both the warm soapy water on some of the coins and the pure acetone in a glass bowl on others.
I did notice that some of the coppers with the soapy water turned almost a salmon pink which looks unnatural, but the slime was highly resistant, and required quite a time soaking before it would start to come loose throught light rubbing. I think this may be a little bit of a hit and miss, depending on what soap you use and the extent of the PVC damage.
With the acetone, the slime came off quickly and the copper did not alter colour. I did rinse the coins afterwards, which did not seem to have an effect.
However, regardless of the method used, the coins simply do look washed... I did not enjoy the washing, as it went against the grain, and only did so due to the extent of the PVC damage as a last resort. The result of washed looking coins rather than sticky, green coins is obviously better, but washing coins is something I hope to never have to repeat.
Please be very carefull with storing coins in PVC packets that are not specifically made for coins (acid free). I am shocked and dismayed that the South African mint are selling these coin storage pockets.
Rubbing your fingers on coins is an issue if they are proof or uncirculated coins. If they are circulated it probably won't matter but I wouldn't recommend it as it can leave hairline scratches. (I suspect it is micro particles of dust, rock, metal, etc. in your prints and not the fingers themselves that do this).
The only problem with washing in water afterwards is what kind of water you used and if you let the coins dry out. Tap water in some areas has chemicals in it, and some people have hard water. This can leave small pockets of gunk that will corrode the coins over time. The acetone will just evaporate. The other issue is not letting a coin dry out, if you put it back in a container to quickly the moisture will cause problems.
You mentioned that the problem was with South African packaging. A lot of the packaging from the 50's, 60's and 70's from the different mints is harmful to the coins. It is not just the plastic either. A lot of the Canadian coins came in felt or velvet presentation boxes, those boxes will cause the coins to get all toned and possibly grimmy. If you have coins from these decades it is probably best to move them to different holders at will not harm them.
