1855 S Seated Liberty Quarter With Restored Date.

Not worth the trouble ty88ty2. I had polished with Bon Ami to make it extra shiny before. Like you I satisfied my curiosity, and while I'm happy that it's a much lower mintage coin than the 1843, it is still in terrible condition. A contender for the worst 1844 Seated dollar in existence.

A good use for the test solution, which had been sitting around for a while.

I wonder if you could do something like this with infrared, UV, or some other photo/scan/whatever technique without the permanent effects. It reminds me of my aunt getting images made from a tintype of a Civil War ancestor, where the original is nearly black with not much of anything discernible, but the resulting copies were very clear. Not that it's worth the expense, just pondering.

Do you have any links to these sort of scopes? I'd be interested.

I couldn't find anything on-line about using microscopy to recover a date on a coin.

The recovered 4 on my dollar looks ghosted. I tried to improve its appearance by viewing under a black light, then by oiling the coin, then by vinegaring, and finally by applying some fireplace soot. None of these improved the appearance, and after all this the 4 disappeared again.

Another drop of test solution brought the 4 back again. All I can guess is that it works by selectively etching higher and lower density metal around the numerals, and that what is seen is a differential etch on a completely smooth surface. It will always be a ghost of a 4...the strike is never coming back...

The solution also caused a few of the worn-off letters on the reverse to appear. But it did not bring back details that are deeply worn off.

There is some literature demonstrating the acoustic microscope to image details on coins that were sanded flat. A previous topic on this site can be found here:

http://goccf.com/t/78162&whichpage=1

Takeaway is this is a specialized piece of equipment that is not common enough for everyone to get their hands on. If you have a friend that works in a materials lab however they might have access.

I put the coin in a glass ashtray and squeezed enough test solution on to cover it. I waited for the solution to go cloudy (less than 10 seconds), then flushed it out under running water in a sink.

Do NOT touch the solution with bare skin.

Gotcha. I think that some of the details on liberty might show up in the same ghostly appearance of the 4 if you soaked it for longer. I've been doing my SLQ's and the Seated quarter here for 30ish seconds, well after the solution turns cloudy. Its more of a pinkish when I take it off if I recall correctly. That being said, you polished yours and it might have changed the surface enough to change how the acid reacts to it and its likely not worth the time... but science!