I've been doing this lately with a bag of dateless buffs I had. So far I've found a 1914, couple 1919's and a 1924. The dates are almost impossible to see unless you're in good lighting.
9 hours in the white vinegar and no noticeable change... other than a few gnats fell pray to the juice... I have to pack everything up for the NCNA show, but I'll repeat the experiment in apple vinegar. I hope it's clear enough to see through.
How can apple vinegar be clearer than white vinegar? Apple cider vinegar has pigments from apples, and sometimes even sediment. It seems like a bad idea to use it on coins, when white vinegar is cheaper, purer, and less likely to stain. Or maybe I'm misunderstanding...
I don't think it is clearer, as I stated I hope it is clear enough to see through. That way I can capture the time lapse video. I had 4 coins in about 1/2 a cup of clear for about 8 or 9 hours and they did not change. https://www.facebook.com/CoinZip/videos/1072048382830379/
If you quicken it up with peroxide it should take just a couple of hours. And for the staining, it is imperative to rinse very well! A good rinse the first time will prevent staining, and a good rinse the second time will ensure that the staining does not come back.
Apple cider has citric acid as well as acetic acid; this seems to quicken up the reaction at any rate. White vinegar will work just as well, but it will take a bit longer. Again, peroxide will make the whole thing go much faster but you've really got to watch it closely to avoid overdoing.
I bought a bunch of dateless buffs at a show one day to have fun with. I did the vinegar soak and did not like the end result. The dates did show over time, but it made the whole coin look corroded, as the pics above show. Then I got Nic A Date and would put a tiny dot of it right where the date would be and let it slightly spread and would give it about 1 minute. I could usually see the date through the acid before I rinsed. I much preferred this way because the rest of the coin is untouched and only a small spot where the date is was a tad darker. I have found several 1914-D and other semi key dates, and they look close to original by using very small amounts of Nic A Date. Some I have seen used a big blob that covers a 3rd of the coin and makes it look bad. Sent from my SM-N920V using Tapatalk
A careful application of nicadate is great! The problem is it is often difficult for people to time it right, and when left on too long or not rinsed correctly, the nicadate spreads and leads to a nasty splotchy look. These failed nicadates can actually be "repaired" with the vinegar trick, although as you noted - the vinegar soak affects the entire surface of the coin, which is not preferable for some. However at the end of the day, acid dated coins are never worth as much as one would like, so it comes down to personal preference, I think. As I've found out, acid or vinegar dating nickels is not a hobby which will make you money! Best used for getting key dates on the cheap.
This is extremely hard to believe. I'm trying to learn here.. So if I put a nickel into "drug store concentration" hydrogen peroxide as you have done (?) it will dissolve? How long is "too long?"
Here's the result that I got on a Null buffalo a few years ago after reading a similar thread on here. I left the nickel in white vinegar for about two days and got a readable 1915.
Back in the '60s I used a product I believe was called 'Silv-A-Date' to restore dates on SLQs. I remember I could see it bubbling as it worked, and did have an acidy odor to it. The date was more visible while the acid was still on the coin, and did turn it black as 'Nic-A-Date' did, which I also used. But to a beginner teenage collector a black acid-dated SLQ was better than a dateless one. I still have a few of them in my collection, and the dates are less discernible now. And no, I don't have it any more, and never found a 1916.
It's not that difficult today to get acid that will etch silver -- any "silver and gold testing" kit contains pure (but somewhat diluted) nitric acid to test for silver. I still don't see why, if it were possible to restore dates on SLQs in this way, we don't see restored-date SLQs in the market.