How to Tone Coins

Might be that nasty zinc in the mixture, plus not every toned area on a cent is caused by oxidation. So we have mostly copper that is mostly oxidized, and we get mostly what we might expect. I fully suspect that a browned, yet having full luster under it cent will yield the best result. In such a case, I doubt serious heating will be necessary. A lustrous but browned cent will likely begin to redden with only moderate heating in an H2 rich environment. Beware: H2 and O2 in a "lazy" mixture can be dangerous. See: Hindenburg, Lakehurst, NJ.

Oh the humanity!

For my experiments using methane, I keep loose woven burlap bags on hand to tie to the posteriors of neighborhood cows. Just add grasses. Voila! Methane and hydrogen sulfide.

 

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OK photos. Sorry - Way out of focus as I went to extreme frame to show as much as possible. Anyway, this is about color not sharpness

 

A coin with that much surface wear can never look believable brightened. It needs to be really MS.

I never pay any premium for color, not plus color on silver, not minus color on copper. Can you tell why?

If an economics major can summon up this much college chemistry, imagine what a pro chemist could do.

Of course, that doesn't stop me from having coins graded that are 63's if they are white, but get 65's because of color. Just because something's stupid (and others who pay premiums for them are) doesn't mean I won't occasionally take advantage of it.

 

Actually an experiment I have done many times in lab (actually the students do it and I just get to lounge around) is to heat a copper wire in a Bunsen burner flame until it is coated with a black copper oxide coat. Still hot, the wire is lowered into a test tube that has some methyl alcohol in it. The vapors of the methyl alcohol react with the copper oxide to make formaldehyde (which we tell the students to have a whiff of) and the copper gets super shiny...now, how can I do this with a coin?

Another thought, a common (not really, but what else) reducing agent is oxalic acid. This used to be the stuff you would use to clean radiators. Put a solution in, run it awhile and then drain it. The oxalic acid reacts with the iron rust in the radiator to make iron (usually as a powder that flushes out) and carbon dioxide. I have dabbled in some experiments with the oxalic acid but haven't had too much success.

 

Put the alcohol in a larger container that's heated to produce more vapor?
I may try this with a RB Unc 1950's Lincoln cent (Shush...don't tell SD I may ruin another coin for posterity).

 

Yeah, but you gotta heat the coin.

 

Right, I plan to hold it in tongs and heat it w/a Propane torch w/a fire extinguisher close by!

 

Let us know.

 

Anybody for fried chicken? That's on the menu for tomorrow..........

 

Nah, I'm shopping for labware and looking for a hydrogen cylinder gas supplier. I have all the regulator gear from my old nitrogen gas stuff to agitate C-41 Developer.

 

How unappetizing........

 

The problem is more one of getting the copper cool enough, fast enough, under conditions which prohibit the reformation of copper oxide. Maybe you could risk your eyesight by quenching the whole thing, suddenly, in some liquid not containing oxygen. Maybe a fluorocarbon, if you can get over the panic-inducing concept of doing anything involving chemistry with fluorine.

 

Hey, developing and printing film bought me the first half of my coin collection, and the first 90% of my knowledge of the chemistry of silver compounds.

 

Oh, that might be a bad idea.

First of all, as I understand it (and I'm not in the industry), different gases have different fittings to prevent costly ("explosive") accidents. So, you'd probably need to build some sort of adapter yourself -- most suppliers probably wouldn't want to help you out.

Second, hydrogen tends to get overly familiar with a lot of metals, especially when it's under pressure. A regulator constructed for nitrogen might weaken and fail catastrophically if used with hydrogen. (Again, no certainty here; if they're all-brass construction, it might be fine. Steel, at least some types, is bad. Aluminum is right out.)

Stick with methanol. If the coin's dark anyhow, consider using a big Fresnel lens to concentrate sunlight onto it within the sealed vessel.

 

And while we're at it, let's just count Zlincolns completely out of anything being discussed here....

 

In, thanks Ken, save the liver for me.

 

People often warn about bad coin advice, I must say that a nitrogen regulator should not be used for hydrogen.

 

I brush my teeth with a product containing fluorine...come to think of it, they put it in my water too.

 

Heating one in a Bunsen burner is a trip.

 

I'm just paranoid after reading Ignition!.