Cleaning Coins.

[Aldebaran]

Some of our sovereigns, the Victorias etc. have grime on them and need cleaning, they look like they were owned by the local coal man.

I am not talking about Brasso, Brillo Pads, jewellers rouge or even carbon tet!!!!!

What is the best way to remove this build up? Can they be washed with soap flakes and patted dry?

Do ultrasound cleaners work, but I’m reluctant to buy another piece of household equipment, we have enough bread makers, steamers etc taking up space.

Thank you 😎

[SeverinDigsSovereigns]

I don't know what works, but I've tried IPA and acetone and they didn't help. Perhaps @GoldDiggerDave could help.

Personally I haven't tried toluene or xylene but those are very harmful.

[Spyder]

If they are just regular bullion without any numismatic added value, then warm/hot soapy water will do the trick. Let them soak for awhile, Then use a soft cloth. NEVER polish them like jewellery. 

Experiment with one and see how it goes.

Edited May 19, 2023 by Spyder

[Stuntman]

Leaving it in olive oil for a few days and then washing in de-ionised water before patting dry on some paper kitchen towelling tends to improve things a bit with UK predecimal silver and bronze coins.  I've never tried this with older gold coins though.

This will loosen the grime and may already have removed some if it.  Then soak a wooden toothpick in olive oil and blunt the end of it, and use this gently to dislodge any big bits of grime once you've soaked the coins in olive oil.  

Be careful though.  If the grime doesn't budge easily, don't be too vigorous with the toothpick - just leave it as it is.

 

 

[Midasfrog]

Give them a soak in hot water and fairy liquid then rinse off brings them up nicely without any polishing 🧐

[SidS]

Why do people feel the need to clean old gold coins? The dirt (and patina) is all part of their charm.

I had some scruffy 1840s gold sovereigns and I thought they were far preferable to the cleaned 1850s ones I had.

Maybe it's the numismatist in me? Cleaning them will destroy any numismatic value they once had, leaving you with only their gold value.

Edited May 20, 2023 by SidS

[Aldebaran]

2 hours ago, SidS said:

Why do people feel the need to clean old gold coins? The dirt (and patina) is all part of their charm.

I had some scruffy 1840s gold sovereigns and I thought they were far preferable to the cleaned 1850s ones I had.

Maybe it's the numismatist in me? Cleaning them will destroy any numismatic value they once had, leaving you with only their gold value.

Thank you, I suppose it is because most coins that I see on here are clean, without the dirt, no matter how old they are.

Although, having said that, I have also seen ‘looks like it’s been cleaned’!!

Interestingly, we have some very old silver coins which we wouldn’t dream of cleaning.

So, like everything in life, it just gets more complicated 🖖

Edited May 20, 2023 by Aldebaran

[Midasfrog]

2 hours ago, SidS said:

Why do people feel the need to clean old gold coins? The dirt (and patina) is all part of their charm.

I had some scruffy 1840s gold sovereigns and I thought they were far preferable to the cleaned 1850s ones I had.

Maybe it's the numismatist in me? Cleaning them will destroy any numismatic value they once had, leaving you with only their gold value.

Depends on the type of coin and dirt. Bullion sovereigns that have been in circulation can pick up a lot of muck . I had some a while back that were sticking together with a build up of dirt , a quick soak in hot soapy water all the sticky grime came off and they looked far better. This method only used on basic bullion not proof collector coins.

[Stuntman]

10 hours ago, SidS said:

Why do people feel the need to clean old gold coins? The dirt (and patina) is all part of their charm.

I had some scruffy 1840s gold sovereigns and I thought they were far preferable to the cleaned 1850s ones I had.

Maybe it's the numismatist in me? Cleaning them will destroy any numismatic value they once had, leaving you with only their gold value.

Not sure I agree with you entirely on this (and I usually do agree with you 🙂).  I've sometimes used olive oil or warm water plus fairy liquid to 'conserve' (rather than clean) some of my predecimal coins, to improve their appearance and eye appeal.

That said, I have only done this with coins that had significant dirt or light verdigris on them, and have been as non-invasive as possible.  If the dirt/verdigris didn't shift then it just remained on the coin as patina and I accepted it for what it is.

So my advice to the OP would be carefully to try the olive oil or warm water/fairy liquid approach if they are not happy with their coins in their current state.  If these methods don't improve things, just enjoy the coins as they are.

[SidS]

15 hours ago, Stuntman said:

🙂)I have only done this with coins that had significant dirt or light verdigris on them, and have been as non-invasive as possible.  If the dirt/verdigris didn't shift then it just remained on the coin as patina and I accepted it for what it is.

Ah but verdigris is a different kettle of fish.

Having gold coins (or silver) that are simply toned - which many regard as dirty, isn't an issue. It can at times even add value. In the US toned coins often command a premium, especially ones that look like they were dropped in an oil slick.

I love toned gold with the golden yellow with slight flushes of orange, or even the odd copper spot. 😁

Verdigris however is a very destructive form of toning, kind of like rust or a form of metallic cancer. Unlike the sulphides on silver, the verdigried form on copper (or cupro-nickel and baser silver coins) not only etches itself into the coin and eats the surface it also spreads across the faces and will also transmit onto other coins. It's a menace and should be dealt with asap, because if not it will destroy the coin altogether. So you do right to tackle coins like that. The choice is treated (cleaned coin) or coin lost.

[Aldebaran]

28 minutes ago, SidS said:

Ah but verdigris is a different kettle of fish.

Having gold coins (or silver) that are simply toned - which many regard as dirty, isn't an issue. It can at times even add value. In the US toned coins often command a premium, especially ones that look like they were dropped in an oil slick.

I love toned gold with the golden yellow with slight flushes of orange, or even the odd copper spot. 😁

Verdigris however is a very destructive form of toning, kind of like rust or a form of metallic cancer. Unlike the sulphides on silver, the verdigried form on copper (or cupro-nickel and baser silver coins) not only etches itself into the coin and eats the surface it also spreads across the faces and will also transmit onto other coins. It's a menace and should be dealt with asap, because if not it will destroy the coin altogether. So you do right to tackle coins like that. The choice is treated (cleaned coin) or coin lost.

Thank you for knowledge, upon reflection I have decided to leave the coins as they are. 
If ever we decide to sell any, the purchaser can make the decision to buy and, if they prefer, clean the coin should they wish.
Meanwhile they can remain in their current condition. 🌞

[SeverinDigsSovereigns]

2 hours ago, SidS said:

Ah but verdigris is a different kettle of fish.

Having gold coins (or silver) that are simply toned - which many regard as dirty, isn't an issue. It can at times even add value. In the US toned coins often command a premium, especially ones that look like they were dropped in an oil slick.

I love toned gold with the golden yellow with slight flushes of orange, or even the odd copper spot. 😁

Verdigris however is a very destructive form of toning, kind of like rust or a form of metallic cancer. Unlike the sulphides on silver, the verdigried form on copper (or cupro-nickel and baser silver coins) not only etches itself into the coin and eats the surface it also spreads across the faces and will also transmit onto other coins. It's a menace and should be dealt with asap, because if not it will destroy the coin altogether. So you do right to tackle coins like that. The choice is treated (cleaned coin) or coin lost.

Gold coins, especially those .917 and .900 ones, can be badly toned, too. Perhaps it's more accurate to call it oxidation, in the form of red spots. If they are allowed to develop they can dent quite deep. I have a 1902 £5 where there was a massive blackspot on St. George's streamer, and ended up with a tiny hole on the coin. But I guess it had to be removed or it would get worse.

It was removed using aluminium foil and baking soda with AA batteries, so the hole definitely didn't result from mechanical removal.

 

Edited May 21, 2023 by SeverinDigsSovereigns

[CazLikesCoins]

On 19/05/2023 at 12:39, Midasfrog said:

Give them a soak in hot water and fairy liquid then rinse off brings them up nicely without any polishing 🧐

Been using it on everything for 50 years. Never found anything it can't get the muck off, even carpets. Brilliant stuff.

 

[SidS]

6 hours ago, SeverinDigsSovereigns said:

Gold coins, especially those .917 and .900 ones, can be badly toned, too. Perhaps it's more accurate to call it oxidation, in the form of red spots. If they are allowed to develop they can dent quite deep. I have a 1902 £5 where there was a massive blackspot on St. George's streamer, and ended up with a tiny hole on the coin. But I guess it had to be removed or it would get worse.

It was removed using aluminium foil and baking soda with AA batteries, so the hole definitely didn't result from mechanical removal.

 

I like the red spots on gold coins, I used to seek out toned gold coins. I don't want my coins to look proof-like or shiny, they just look new.

[SeverinDigsSovereigns]

9 minutes ago, SidS said:

I like the red spots on gold coins, I used to seek out toned gold coins. I don't want my coins to look proof-like or shiny, they just look new.

Personally I have very different opinions on gold and silver. Gold has been used as a store of value exactly because it doesn't react with air and always looks fresh, so I like gold coins as shiny as new. Silver was more or less a by-product of gold and used by the plebeians, so it makes sense to expect toned silver. Some will be better toned than others, and there's much value attached to that (and silver itself isn't very valuable anyway).

So I would argue that there are different psychologies regarding silver and gold. Moreover, gold stands out among all PMs because it's coloured, and the shiny lustre is its charm.

Edited May 21, 2023 by SeverinDigsSovereigns

[SeverinDigsSovereigns]

1 hour ago, SidS said:

I don't want my coins to look proof-like

And I agree with  this. The PL 1887 are cringe. I've been looking some 1887 £5 with lustre for a long time but all available on the market are proof like versions. But that has noting to do with toning though.

[Silverlocks]

On 19/05/2023 at 10:32, Aldebaran said:

Some of our sovereigns, the Victorias etc. have grime on them and need cleaning, they look like they were owned by the local coal man.

I am not talking about Brasso, Brillo Pads, jewellers rouge or even carbon tet!!!!!

What is the best way to remove this build up? Can they be washed with soap flakes and patted dry?

Do ultrasound cleaners work, but I’m reluctant to buy another piece of household equipment, we have enough bread makers, steamers etc taking up space.

Thank you 😎

The gunge is dirt and skin oils caked and polymerised on over the ages.  Most sovereigns pre-date the clean air act, and were manufactured and circulated bang in the middle of the coal-fired industrial revolution.  They can get pretty grubby with this gunge; this is not toning or aging on the coin, which can also happen and manifests as brick red patina on the coin.  

In order of efficacy - 10% ammonia solution (use distilled water) > acetone > isopropyl alcohol.  Soak the coins for a little while, swab gently with a paper towel or cotton swab.   Ammonia won't react with gold, but don't use it on copper as it will form soluble cuprammonium complexes with most copper salts and dissolve the toning leaving you with pink coins.

As to whether serious numismatists really like patina on their coins - let's just say that when I go to the London Coin Show I see dozens of trays of bright, shiny, gleaming gold coins with no visible dirt or patina on them.  These are typically 100-200 years old (and sometimes even more) circulated right through the coal-fired, sulphur laden, pea soup smog industrial revolution.  Bright, shiny, clean.  All of them.  Make of that what you will.

Edited May 21, 2023 by Silverlocks

[Silverlocks]

8 hours ago, SeverinDigsSovereigns said:

Gold coins, especially those .917 and .900 ones, can be badly toned, too. Perhaps it's more accurate to call it oxidation, in the form of red spots.

There are a couple of things that can happen to gold.  Red spots are gold oxide (and will decompose at 160°C.  They are normally formed by electrolytic reactions with impurities in the surface of the gold.  There is also a brick red patina that is (I think) sulphide.  Apparently HCl based dips can remove the latter, but should be approached with caution.

[SeverinDigsSovereigns]

4 minutes ago, Silverlocks said:

There are a couple of things that can happen to gold.  Red spots are gold oxide (and will decompose at 160°C.  They are normally formed by electrolytic reactions with impurities in the surface of the gold.  There is also a brick red patina that is (I think) sulphide.  Apparently HCl based dips can remove the latter, but should be approached with caution.

I think it can be silver sulphide (and other chalcogenides) and some oxides/sulphides of copper. I quite doubt if gold will react with surface impurities under ambient conditions. I am aware that cyanides can corrupt gold at room temperature but that is less likely the cause. You mentioned the coal-fuelled industrial revolution and there was an abundance of sulphur, selenide, etc. in the air and they are highly susceptible to reacting with silver and copper than gold itself.

According to 

https://chem.libretexts.org/Ancillary_Materials/Reference/Reference_Tables/Electrochemistry_Tables/P1%3A_Standard_Reduction_Potentials_by_Element

the standard potential of gold (III) forming is +1.52V, which is quite difficult.

As for why aluminium foil works: aluminium has a standard potential of -1.616V, which means you can dip whatever stuff in baking soda and aluminium spontaneously acts as the anode and gets oxidised. In return, silver chalcogenides, copper/gold oxides just get reduced and become the elements. This way no material is removed from the surface of coins and can be considered safe. Baking soda is the electrolyte and is safe because neither sodium nor carbonate ions react with the metals. Other electrolytes, such as salt, contain chloride which 1) irreversibly binds with silver and form ugly layers 2) dissolves gold like ammonia does to copper.  

Off topic but I've tried on some bullion coins heating with butane flame (which reaches up to 1600 °C). It turns any silver coin to a matt finish which is quite good-looking if you've got any spare silver to play with. Heating a sovereign oxidises the copper and makes copper precipitate on the surface of the coin as copper moves around and finds its way with oxygen. If you remove the oxides this heated sovereign permanently becomes pinker.

[Silverlocks]

19 minutes ago, SeverinDigsSovereigns said:

I think it can be silver sulphide (and other chalcogenides) and some oxides/sulphides of copper. I quite doubt if gold will react with surface impurities under ambient conditions. I am aware that cyanides can corrupt gold at room temperature but that is less likely the cause. You mentioned the coal-fuelled industrial revolution and there was an abundance of sulphur, selenide, etc. in the air and they are highly susceptible to reacting with silver and copper than gold itself.

According to 

https://chem.libretexts.org/Ancillary_Materials/Reference/Reference_Tables/Electrochemistry_Tables/P1%3A_Standard_Reduction_Potentials_by_Element

the standard potential of gold (III) forming is +1.52V, which is quite difficult.

As for why aluminium foil works: aluminium has a standard potential of -1.616V, which means you can dip whatever stuff in baking soda and aluminium spontaneously acts as the anode and gets oxidised. In return, silver chalcogenides, copper/gold oxides just get reduced and become the elements. This way no material is removed from the surface of coins and can be considered safe. Baking soda is the electrolyte and is safe because neither sodium nor carbonate ions react with the metals. Other electrolytes, such as salt, contain chloride which 1) irreversibly binds with silver and form ugly layers 2) dissolves gold like ammonia does to copper.  

Off topic but I've tried on some bullion coins heating with butane flame (which reaches up to 1600 °C). It turns any silver coin to a matt finish which is quite good-looking if you've got any spare silver to play with. Heating a sovereign oxidises the copper and makes copper precipitate on the surface of the coin as copper moves around and finds its way with oxygen. If you remove the oxides this heated sovereign permanently becomes pinker.

You can remove red spots by heating, but it only needs to get up to 160 degrees so you don't need to cook the coins.  There are a few videos on YT about it.  I guess if you overheat the coins you can oxidise the gold or alloyed materials.