Treatment of "bullion" 90% - especially the 64 JFK

[68Camaro]

Who here has ever used (or does so on a regular basis) the magnesium or aluminum based electrolytic tarnish removal technique? This relies on putting the tarnished silver-based metal on top of a sheet of either magnesium or aluminum (such as Al foil) in a bath of sodium bicarbonate laced warm water? The Mg or Al pulls the sulpher from the silver sulphide tarnish and leaves the underlying coin relative unscathed.

I realize this isn't for use on numi coins! Let's not have that discussion - I know that.

But for "bullion" coins, with bath treatments kept fairly brief, it does a fabulous job of cleaning up minor tarnish without damaging (under 10x mag, as best as I can tell) non-numi coins.

For those that have, does anyone beside me use it on a regular basis on non-numi coins? My use is limited to circulated 64 JFKs, which will never be collectable for numi reasons. They are fundamentally a bullion coin, with >500,0000,000 minted with that one year, and most still around.

Up to recently I was segregating my 64 JFKs into clean coin and tarnished coin and keeping the tarnished rolls separate. Recently I started using this technique on the tarnished coin and found that 90% of them came clean within a couple of minutes. Another 5% take a bit longer, and a couple of percent just don't clean well (have imperfections that this won't remove - so I just pull them and keep them separate).

[beauanderos]

So what do you do? Put the solution in, say, a cookie tray with just enough to cover the coins and then wait a few minutes? Do you have to turn the halves over for this to work?

Does this method merely remove tarnish and perhaps a dull finish... or does it produce a high lustruous effect?

[68Camaro]

So what do you do? Put the solution in, say, a cookie tray with just enough to cover the coins and then wait a few minutes? Do you have to turn the halves over for this to work?

Does this method merely remove tarnish and perhaps a dull finish... or does it produce a high lustruous effect?

Yes. I do rotate the halves every couple of minutes to avoid the possibility of pitting. It just removes the black. The finish below is whatever was there. If a proof, it's proof-like. If AU, it's shiny but not polished. It doesn't polish the surface at all.

Severe crevice tarnish doesn't get removed well, and while it might eventually get removed I don't like to leave them in long enough for that as I don't want to risk damage to the rest of the surface, so some coin (a couple of percent) are improved but still have black in the crevices. I just leave them like that.

[silver]

Ray,
You can try that on the halves I sent you. They will be a challenge.
ED

[slickeast]

I used that method once with a silver chain my daughter wanted to wear. It started off black and cleaned up pretty good. Not perfect but it looked a lot better. I used salt in very hot water. I stirred it until most of it dissolved and used some aluminum foil.

[68Camaro]

I tried the salt (as well as a half salt half bicarb mix) and felt the salt was risky, that there was a chance that an undissolved piece would start a local corrosion cell where I didn't want it. That's the same reason I rotate the coins every couple of minutes.

The bicarb is safer, and dissolves better. A teaspoon in a quart of warm/hot water (I use an old peanut butter jar, and shake it until dissolved) provides the necessary electrolytes to encourage the reaction.

You'll get bubbles on the coins, which break free and rise to the surface, and a light smell of sulpher in the air.

I then wipe clean with a paper towel. Some will require a couple of repeated doses. It will quickly become evident if you've got a coin that is too dirty to clean safely.

The resulting coins are very clean, and will accept fresh finger prints easily. You might want to wear gloves in the final stage if you don't like fingerprints back on the coins.

[Diggin4copper]

works well on metal detected coins.. even semi numismatic ones..