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Ozzy1977

How to deal with sticky coins?

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Hi I was given almost a full set of half crowns (47-67) all of which are in fine condition, except they have an unknown sticky coating on them, it feels like a wax that hasn't been buffed .  I know coins should not be cleaned so how would I be best advised to tackle this sticky issue?

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Petrol will work in most cases, followed by a wash in pure acetone, neither of these will alter the coin physically. But most important is not to rub the coin surfaces, nothing more than a dab with clean cotton wool or soft artists brush to wash away any softened residue. As ever, practice first on a less valued coin.

Jerry

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I'd try just the acetone first & forget the petrol unless the acetone didn't work. :)

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I found that using either petrol or acetone will dissolve/remove anything on the coin and when left to dry will leave a whitish waxy looking area in places.this can be seen more clearly the more residue that was on in the first place.Using distilled water straight after putting anything on should help remove it more thoroughly ,put the coin in the water in a plastic tub,swish it around for a minute then pat dry with a lint free cloth.

Better not to do anything in the first place but if the coin is already ruined it cant really appear much worse regardless of what you do 😉

Everyone uses different methods including three in one oil for silver which if only a tiny amount may help.

I would think most of the years you mention you can pick up cheaply ,so maybe worth just replacing them before spending a few quid on cleaning stuff .

 

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I've only ever used acetone but I think I've seen xylene recommended as well?

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Maybe - I've never used it - but I think between them acetone and xylene should remove most things that can be removed (I assume one is polar and the other is non-polar).

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You can try metho. I don't know about the UK but in Australia you can buy it without the purple dye. I find it good for cleaning and degreasing bronze and silver coins. I have never experienced any reaction between the spirit and a coin.

Edited by ozjohn
spelling

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Mr T water H2O is a polar molecule. That's what gives its ability to dissolve so many things.

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On 28 October 2018 at 7:21 AM, ozjohn said:

You can try metho. I don't know about the UK but in Australia you can buy it without the purple dye. I find it good for cleaning and degreasing bronze and silver coins. I have never experienced any reaction between the spirit and a coin.

In UK you can buy Surgical Spirit, which I assume is meths without the dye?

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22 minutes ago, Peckris 2 said:

In UK you can buy Surgical Spirit, which I assume is meths without the dye?

Yes - I have used this for years and I personally find it better than acetone, particularly if you add a little detergent.

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Petrol is best put in cars !

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3 hours ago, copper123 said:

Petrol is best put in cars !

Except that it is much more effective than acetone at softening or dissolving the waxy residue around the lettering on some of our well handled bronze, enabling it to be gently removed with a soft brush. To be fair I only do this sort of thing under high magnification using a binocular microscope, the same one I use for archaeological conservation work. IPA, DMSA and Industrial meths also seem inert as far as the coin is concerned. Petrol of course has a multitude of additives, and to be safe the coin needs a wash in acetone after treatment. Don’t knock it if you haven’t tried it,  most collections (not yours of course  Pete) will have a dirty and  inexpensive coin to practice on, and get a fine artists brush and cut the bristles to 1/4 inch.

Jerry

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2 hours ago, jelida said:

 (not yours of course  Pete) will have a dirty and  inexpensive coin to practice on, and get a fine artists brush and cut the bristles to 1/4 inch.

Jerry 

I really will have to try the artists paintbrush thing , I prefer acetone and will leave petrol to others.

The first thing I do when I add a coin to my collection is give it a wipe with toilet paper and acetone , I find surprisingly, that very few dealers use it and it always improves most everything I buy .

Toothpicks are great for dirt as well

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On 10/30/2018 at 2:35 AM, jelida said:

Petrol of course has a multitude of additives

This is mostly why I'd avoid it.

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31 minutes ago, Mr T said:

This is mostly why I'd avoid it.

Thankfully very inert, at least as far as metals are concerned, I’d even use it in my cars! The copper alloy parts in my 60 year old Landrover carburettor remain pristine, if a little worn. Any worries of even long term coin damage are misplaced, and this applies to most of the easily available organic solvents, though as stated above I always use a precautionary 100% acetone wash as a final step. Olive oil, widely used apparently on coins, is far worse as it oxidises into an acidic compound which does have damage potential. And the waxes and oils that accumulate around the details of handled coins likewise are sources of the salts that initiate and maintain verdigris, letting those deposits remain is itself a long term risk, and the main reason for the development of verd for example on slabbed coins.

Jerry

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I prefer acetone but recently had a problem. I've bought a large quantity of uncirculated old round pounds that have spent their entire lives in plastic flips and look a bit shabby.

A new litre of 100% acetone was bought via fleabay but didn't seem to be doing any good. As I was working outside anyway I decided to leave 2cc of acetone in a shallow dish, and see how long it took to evaporate. 37 hours. I've got my money back, but there is some misdescribed stuff out there.

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4 hours ago, jelida said:

Thankfully very inert, at least as far as metals are concerned, I’d even use it in my cars! The copper alloy parts in my 60 year old Landrover carburettor remain pristine, if a little worn. Any worries of even long term coin damage are misplaced, and this applies to most of the easily available organic solvents, though as stated above I always use a precautionary 100% acetone wash as a final step. Olive oil, widely used apparently on coins, is far worse as it oxidises into an acidic compound which does have damage potential. And the waxes and oils that accumulate around the details of handled coins likewise are sources of the salts that initiate and maintain verdigris, letting those deposits remain is itself a long term risk, and the main reason for the development of verd for example on slabbed coins

Very worrying. However, I guess there's no oxidation if the coin is kept fully submerged in the oil, then gently wiped free of all traces on removal? 

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11 minutes ago, Peckris 2 said:

Very worrying. However, I guess there's no oxidation if the coin is kept fully submerged in the oil, then gently wiped free of all traces on removal? 

One would have to exclude oxygen during the soaking process or the oxidation of the oil will happen. Of course the acidic effect on the coin is what gently removes the patina and initially can make it appear nicer. The difficulty is removing the olive oil fully afterwards, impossible if a heavily patinated coin has had a prolonged soak. There are academic articles on this that I have read in the deep past but I can’t remember where. Perhaps in a conservation publication.

Jerry

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Yikes, I am scared of xylene and had just  a bit too much chemistry to use that one.

A possible "treatment" algorithm that I use is:

 

Warm soapy water (with dish detergent) and use of fingers to work it into the crevices and then liberal wash with same tap water (if there are not too many minerals in it) and then tamp dry with a high nap white cotton towel.

Acetone works well, but this is what I do: First buy it from Home Depot (or equivalent) - this works out in the States to be about 6-8 quid

I soak one of those same high nap white cotton towels and then tamp the surface - NO RUB - and then use a soaked cotton bud (the kind with looser cotton head on it) and use the same tamp method.   I then wash liberally with water and detergent and then just water. Tamp dry with towel.

If these don't work, or there is oxidation on/in the surface metal, I pull out the household ammonia (the kind without dye) and use the soak method, then follow with the same old cotton bud tamp treatment; then the soap and water, followed by the water. Tamp dry with towel.

The next choices are a bit tougher as I don't know what sorts of coin cleaning products are available in the UK now. I use the same tamp application method and always follow with the soap and water, then water and tamp dry procedures.... I have used MS70, Coin Care and Blue Ribbon....

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20 hours ago, jelida said:

One would have to exclude oxygen during the soaking process or the oxidation of the oil will happen. Of course the acidic effect on the coin is what gently removes the patina and initially can make it appear nicer. The difficulty is removing the olive oil fully afterwards, impossible if a heavily patinated coin has had a prolonged soak. There are academic articles on this that I have read in the deep past but I can’t remember where. Perhaps in a conservation publication.

Jerry

Hmm. I was going to soak a high grade 1868 penny with a small bit of 'green', but now I'm wondering if there is an alternative to olive oil? I was going to use medicinal olive oil (BP) but I don't know if that makes a difference?

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6 minutes ago, Peckris 2 said:

Hmm. I was going to soak a high grade 1868 penny with a small bit of 'green', but now I'm wondering if there is an alternative to olive oil? I was going to use medicinal olive oil (BP) but I don't know if that makes a difference?

I dont think that is one of your best ideas Peck 😊 The idea is you practice with a cheap one ,not end up with something glowing or a different.colour.

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Just now, PWA 1967 said:

I dont think that is one of your best ideas Peck 😊 The idea is you practice with a cheap one ,not end up with something glowing or a different.colour.

I've used olive oil before! It's just that the comments here have given me the heebie jeebies.

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4 minutes ago, PWA 1967 said:

Heebie Jebbies 😂

If it wont pick off leave it alone IMO.

How would you do that? :o

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