Rapid Toning Of Lincoln Memorials

Interesting. Reminds me of rapid oxidation like what happens to shipwreck items if not properly adjusted to the atmosphere?

I'm sure BadThad will weigh in when he posts today's wheats in the tribute thread

This is very unusual, copper toning takes time, like a months and years time scale unless subjected to high heat. I suspect your eyes are playing tricks on you and the change was there but you just didn't notice at first. How about posting some pictures?

difference in light and viewing angles between t=0 and t=45 minutes? Different light source (e.g., cloudy to direct sun?; no overhead light source to overhead light source?)?

Well, this is a PRIME example of why you shouldn't believe everything on the web. First off, mineral oil is NOT soluble in acetone, you must use xylene or another non-polar solvent to remove oils (including the often recommended olive oil).

Secondly, where the author was dead-wrong, it appears he was trying to address the removal of verdigris. Verdigris salts are insoluble in oil, oil is the WORST possible choice for this and oft recommended by the ignorant.

Finally, oil will NOT "turn a coin purple". I have no idea where he came up with that load....it's 100% incorrect.

Welcome to the CC forums! I'm not trying to dig on you, it's just that misinformation spreads like wildfire. I don't want a "google searcher" finding this thread and then believing these things are true when they are not. The volume of bad information on coin conservation over the web far exceeds the good!

Well done.

As far as lighting differences, no, there wasn't different. I was in the same spot. Same for angle of viewing. I can't really post pictures that would help because I don't have a "before" for comparison.

Two variables that I considered were 1)that the only light source I was using was direct sunlight and 2) I was sorting the coins on a wool carpet. We know what full spectrum light does to coins, but it usually takes longer. As for the wool, I hope this is not another mineral oil meme, but I thought I'd read somewhere that "natural" fibers were not good for some metals.

So, yes, I'd like to hear what the chemists have to say about it.

CoinHunterDrew,

It's definitely similar. Fingerprints I didn't see on some of the bright coins showed fingerprints along with the purplish toning. And I should stress here that by bright coins I'm talking about the ones you get in change that are basically EF to AU, right out of a bank roll. They went from my pocket to the jar. The latest penny in there was 1981, the year I graduated high school, so no funky, copper plated zinc-lings.

I wish I had a dedicated coin-room. I used to work in an area of the basement that was cool and constant, but it's lit by an overhead CF-spot and a full spectrum floor lamp. The idea of the full spectrum light was to supplement sparse winter sunlight during long WI winters. However, one time I left some stacked coins, including SBA and Eisenhower clad dollars out on the desk. The light got left on for a couple days and when I went back to the coins, all the top coins in the stacks had blackened. I need a new lamp. BTW, what's the best light to use when working with coins? Have you seen a thread on that topic?