Cleaning bronze after olive oil dip

[Gary D]

I've got a nice penny that had a spot of the green stuff. It's currently in olive oil which is working well. What is the normal procedure for removing the olive oil once the penny is removed from the dip.

[Coinery]

I've got a nice penny that had a spot of the green stuff. It's currently in olive oil which is working well. What is the normal procedure for removing the olive oil once the penny is removed from the dip.

Rightly or wrongly, I only ever wipe/pat(Peter) off as much as I can to make the coin dry in appearance again. I never remove ALL the oil residue with something else, like acetone for example.

Copper/brass coins always look beautiful after a wipe of oil, almost conditioned but, I have asked the question on here many times, whether anyone has ever noticed any long-term effects from exposure to Olive Oil. I think I recall Peck saying that he hadn't noticed any changes, in around 80-90 years of observing I think it was (don't quote me on that, it might be longer)

Am I going to get hate mail for this, but I routinely acetone and oil my copper coins before sealing them up in 2x2's. I've been doing that for around 4 years and haven't noticed any changes yet.

[Peter]

Come on Stuart. Don't wipe Pat give her a tickle first.

[Coinery]

Come on Stuart. Don't wipe Pat give her a tickle first.

I do know a Pat, and can't get that thought out of my head now!

[Peckris]

I agree. I think a faint sheen caused by a very thin film of olive oil positively enhances a coin (but don't tell Popeye )

[Peter]

I agree. I think a faint sheen caused by a very thin film of olive oil positively enhances a coin (but don't tell Popeye )

I covered my Brutus with Olive oil and had a pipe smoking sailor "chase me"

He was trying to put a knife in my back.

[Peckris]

I agree. I think a faint sheen caused by a very thin film of olive oil positively enhances a coin (but don't tell Popeye )

I covered my Brutus with Olive oil and had a pipe smoking sailor "chase me"

He was trying to put a knife in my back.

Oh, what was that guy's name - Duncan Somebody?

[Nick]

I agree. I think a faint sheen caused by a very thin film of olive oil positively enhances a coin (but don't tell Popeye )

I covered my Brutus with Olive oil and had a pipe smoking sailor "chase me"

He was trying to put a knife in my back.

Oh, what was that guy's name - Duncan Somebody?

Duncan Norvelle.

[Peckris]

I agree. I think a faint sheen caused by a very thin film of olive oil positively enhances a coin (but don't tell Popeye )

I covered my Brutus with Olive oil and had a pipe smoking sailor "chase me"

He was trying to put a knife in my back.

Oh, what was that guy's name - Duncan Somebody?

Duncan Norvelle.

That's him! Completely straight, apparently.

[Gary D]

Well here it is warts and all. I thought it had come up pretty well until I photographed it My one concern is that the oil will attract dust and fluff.

[Gary D]

[Coinery]

Well here it is warts and all. I thought it had come up pretty well until I photographed it My one concern is that the oil will attract dust and fluff.

You don't want the surface wet and gummy with oil! get it (wipe) to a state where dust would blow off the surface, as with any coin! Absorbent tissue sucks it away from the surface quite nicely with a bit of 'tickling'!

[Peckris]

Well here it is warts and all. I thought it had come up pretty well until I photographed it My one concern is that the oil will attract dust and fluff.

It will attract gunk if stored outside a cabinet or enclosed tray. You could keep in a flip but you'd need to monitor it closely. Also, the film of oil should be incredibly fine (i.e. you've wiped most of it off, but there is just a sheen left).

[Coinery]

You could keep in a flip but you'd need to monitor it closely.

Just to continue what I'm enquiring into elsewhere, do you think there's a greater risk, FULL STOP, when sealing coins in flips, or just when Olive Oil is involved? I'm just thinking out loud here, but I guess Olive Oil has a water content?

God, what's the REAL science here, what do the museums do, or are they as bad, or worse?

[Peckris]

You could keep in a flip but you'd need to monitor it closely.

Just to continue what I'm enquiring into elsewhere, do you think there's a greater risk, FULL STOP, when sealing coins in flips, or just when Olive Oil is involved? I'm just thinking out loud here, but I guess Olive Oil has a water content?

God, what's the REAL science here, what do the museums do, or are they as bad, or worse?

I wouldn't think so - at least, not in 'free' form where it can act like water.

A coin in a flip isn't 'sealed' as such, as the envelope is not airtight. But given that modern flips aren't PVC there shouldn't be a major problem, but if it was me I would still be monitoring it, olive oil or not. As far as the chemistry is concerned, could the olive oil react with the plastic of the flip? Over to the chemists here..

[Mr T]

I wouldn't think olive oil would react with plastic (my knowledge of chemistry isn't great but I didn't think acids affected plastic). I thought olive oil expired or went off though but I don't know if that changes anything.

[Coinery]

I wouldn't think olive oil would react with plastic (my knowledge of chemistry isn't great but I didn't think acids affected plastic). I thought olive oil expired or went off though but I don't know if that changes anything.

Another good point! So, what happens chemically when olive oil goes off? Is it a danger to coins at that point? Certainly smells different when very old, so what happens?

Also, when I talk about 'flips' in the above, I'm referring to the glued shut 2x2's with the circular plastic windows in them.

[ChKy]

In order to remove plaques of corrosion a solution of EDTA proved to be quite useful. By that kind of treatment the green deposit is removed within minutes.

DISCLAIMER: You apply that treatment to your coins at your own risk. I am not responsable for any kind of disappointment

Edited January 26, 2013 by ChKy

[Sheencrofter]

I've just bought an Hibernia coin with a few spots of the green stuff and at the moment its resting in a plastic tub with rain water and a few grains of Bicarbonate of Soda disolved in it. I got the idea from the address below when i was trawling google for a few ideas how to remove it.

I should add that was before I had the sense to look on this forum

http://reviews.ebay.com/How-to-Remove-Verdigris-From-Coins?ugid=10000000017991989

[copper123]

I have heard that the black finish farthings 1897-1918 look superb with a quick dip in car oil

[Mr T]

Another good point! So, what happens chemically when olive oil goes off? Is it a danger to coins at that point? Certainly smells different when very old, so what happens?

Also, when I talk about 'flips' in the above, I'm referring to the glued shut 2x2's with the circular plastic windows in them.

Not sure. Maybe the acids react with air and the solution becomes non-acidic. I'm sort of guessing here.

I believe http://en.wikipedia.org/wiki/Polyethylene_terephthalate is what the plastic in flips/2x2s and if you do a bit of quick googling you'll see that PET a.k.a polyester takes forever to break down, but acid can hasten the process.

In order to remove plaques of corrosion a solution of EDTA proved to be quite useful. By that kind of treatment the green deposit is removed within minutes.

Does it leave copper coins with a pitted surface?

Edited January 26, 2013 by Mr T

[TomGoodheart]

God, what's the REAL science here, what do the museums do, or are they as bad, or worse?

I'm sure I read somewhere that museums varnished their coins to protect them. Whether that's still the case, I don't know. But remember, a museum display used to be designed to make the coin look nice and then protect it. I'm not sure if they were bothered if the coin toned over time, nor that the finest little details folk here might be interested in were retained ...

I've seen some coins that have traces of having been written on in ink, scratched with numbers (whether by a museum I'm not sure, but surely not by a numismatist?) and of course, many museum specimens were dumped into a dusty drawer where they probably still languish today, so they aren't all preserved as we might wish.

In other words, the long term preservation aims in a museum might be rather different from those of coin collectors, making whatever they do less useful to us.

Anyone ever worked in that area that could enlighten us? Clive?

[Peckris]

Does it leave copper coins with a pitted surface?

That will be inevitable I'm afraid, where the verdigris has actually eaten away the affected surface of the coin. The only alternative is to convert the verdigris itself into another, non-corrosive substance - it may be that diluted vinegar will do that? Not sure - it will certainly lighten the rest of the coin and leave the verdigris as a dark patch, but not green.

[ChKy]

Does it leave copper coins with a pitted surface?

That depends how deep the coorosion went through the material. EDTA do not desolve the elementary metal atoms, but the charged metal ions within the green copper carbonate.

[ChKy]

edit: That copper carbonate dots are very harmful anyways and you have to remove them. By time the coins surface will be destroyed and other coins affected/infected. In German we have a word for that: Bronzepest (bronze & pest/plague)