Cleaning Gold Coins - At Your Own Risk

[danmc82]

I've had a couple of half Sovereigns that have looked abit grubby since I've owned them. Its always annoyed me so I thought I'd do something about it. I've also seen alot of members asking about the cleaning of coins.

The coins in question are both Proofs from 1980 and 1982. I bought them on the second hand market, not expecting perfect coins.

I did alot of reading up on the best way to clean them. Theres loads of info out-there so I choose one of the cheapest and probably easiest to do. And so I decided to use Acetone and Distilled water.

Other things I used were...

• Head Torch
• Cotton Buds
• Cotton Gloves
• Loupe
• Kitchen Paper Towel.

I'm not a very good photographer but I think the pictures I took did an ok job in showing the before and after.

Step 1: Put on cotton gloves before handling any coin, especially Proofs. I only put one on and tipped the coin into that hand. I then placed it down onto my other glove.

Step 2: I dipped my Cotton bud into the Acetone and let it soak for a few seconds. I then proceeded to gently wipe over the coin. At first nothing happened so I proceeded to push with a little more       effort until it made some difference. I'd say I used the same force as if I was rubbing out a pencil mark on paper.

Step 3: Once I was happy that I'd removed any dirt/fingermarks that I could see, I then picked up the coin and placed it onto kitchen paper. (Remember to wear the gloves when picking up.

Step 4: I then soaked the coin in distilled water and used a clean cotton bud to gently wipe over the coin to help remove any remaining Acetone.

Step 5: I folded the paper over the coin until it was completely dry. I left to air dry also for about 10 minutes.

Step 6: Proceed with the other side and follow the same steps as before.

Step 7: Admire your newly cleaned Gold Sovereign.

Before Pics...

1980

 

After cleaning and drying I put the coin back into the capsule before taking pics. I didnt want to take it back out again so took the pics inside the capsule.

The last two are with a Loupe...

 

 

1982

Before...

After...

I hope this helps someone out but please be careful, and remember this is at your own risk. Just because it worked for me, doesnt mean it'll work fo you.

I also dont know how this would work with 24ct Gold coins as they are softer and more prone to scratching than a 22ct Coin.

 

[sovereignsteve]

It can be done as you have found. The only suggestions I have are don't wipe, just lightly press down and experiment with acetone and water dipping along with drying until you get a method that doesn't leave any drying marks.

[ZatStackz]

I've done acetone soaks, but I've never used a q-tip because I heard they can leave micro abrasions.  Also the material that you are wiping off the coin could possibly scratch it as you remove it.  Its hard to tell from your pictures, but are there any tiny scratches from the q-tip?  Also, like you said, the results might be different on silver or on 24k gold.

Would the results have been the same just soaking in acetone for a few minutes, then rinsing?

[danmc82]

13 minutes ago, ZatStackz said:

I've done acetone soaks, but I've never used a q-tip because I heard they can leave micro abrasions.  Also the material that you are wiping off the coin could possibly scratch it as you remove it.  Its hard to tell from your pictures, but are there any tiny scratches from the q-tip?  Also, like you said, the results might be different on silver or on 24k gold.

Would the results have been the same just soaking in acetone for a few minutes, then rinsing?

No idea, maybe. As @sovereignsteve says, rubbing may not be the best choice but it seemed to work ok with me. Light touching didnt seem to do anything.

I cant see any damage done to the coin from the Cotton bud, but maybe my Loupe isnt powerful enough to see that close.

I've now added the 1982 to the first post.

My happy Clean Sovereigns ...

 

[ZatStackz]

 Was that coin stored in an oil vat? 

It definitely looks much better afterwards to my untrained eye.  Maybe someone more experienced than me can answer this.  Would it get a "cleaned" designation if it were sent for grading?

[sovereignsteve]

6 minutes ago, ZatStackz said:

It definitely looks much better afterwards to my untrained eye.  Maybe someone more experienced than me can answer this.  Would it get a "cleaned" designation if it were sent for grading?

depends if any faint hairlines can be seen under a x5 loupe, and whether the grader got out of bed on the wrong side that particular morning😁

[danmc82]

Good job im not grading them then 😋

[Pete]

I've done exactly the same to remove stains ( usually caused by a fingerprint ) on proof gold coins.
However if you examine the coin very closely, usually with a loupe and tilt the coin to a low angle of incidence, illuminated by a strong light, you may find a few extremely fine scratches.
These would appear on the brightly polished flat surfaces and are caused by tiny particulates that have been rubbed across the surface, so the first thing to do is to dab the acetone using a cotton ball, soaking the surface then rinse prior to any rubbing with a cotton bud. I would like to know the method used by NGC in "restoring" such coins - have they got a technique that we could use ? I can envisage a method perhaps using a pressurised spray of solvent like acetone, pure ethanol then distilled water in a chamber avoiding all contact with a wipe. Would a hobby paint spray gun be a good idea ? Spray the coin with short blasts of solvent into a large jar or container for example ? If doing a lot, collect the solvent and reuse after passing through a fine chemistry filter paper.

[danmc82]

@Pete I've got a pressure washer 😁

I dont think my 100ml of Acetone would last very long though.

I've not tried soaking as someone mentioned before. Maybe a good long soak and then an ultra sonic cleaner may get the job done.

I dont have anymore dirty coins to try though.

[Pete]

26 minutes ago, danmc82 said:

@Pete I've got a pressure washer 😁

I dont think my 100ml of Acetone would last very long though.

I've not tried soaking as someone mentioned before. Maybe a good long soak and then an ultra sonic cleaner may get the job done.

I dont have anymore dirty coins to try though.

I've found that soaking then using an ultrasonic bath often doesn't work.
To remove hardened greasy stains the surface needs to be wiped ( causing scratches in some instances ) or maybe (??) blasted in a jet of solvent like acetone.
I too have a Karcher but that's for cleaning the paths.
I was thinking about the hobbiest paint sprayers - but I know you knew that 😂

 

[danmc82]

15 minutes ago, Pete said:

I was thinking about the hobbiest paint sprayers - but I know you knew that 😂

Nope, had no idea 🤣

I think my Coins came out better than I was expecting and to me I cant see any scratches with the naked eye, or with a low powered Loupe so I'm happy.

I'll never get them graded and I'll never look close enough to see any scratches (If any) caused by the cleaning.

They look 100% better to me so I'm very pleased 👍

[sovereignsteve]

41 minutes ago, Pete said:

I've found that soaking then using an ultrasonic bath often doesn't work.
To remove hardened greasy stains the surface needs to be wiped ( causing scratches in some instances ) or maybe (??) blasted in a jet of solvent like acetone.
I too have a Karcher but that's for cleaning the paths.
I was thinking about the hobbiest paint sprayers - but I know you knew that 😂

 

Ultra sonic baths need some kind of cleaning solution to be used. They only work by helping the cleaning process via loosening the particles using sound waves, they aren't a panacea on their own.

I haven't tried it but using acetone or similar in the bath should do the trick without any physical contact on the coin surface.

[Pete]

12 minutes ago, sovereignsteve said:

Ultra sonic baths need some kind of cleaning solution to be used. They only work by helping the cleaning process via loosening the particles using sound waves, they aren't a panacea on their own.

I haven't tried it but using acetone or similar in the bath should do the trick without any physical contact on the coin surface.

I have a basic jeweller's ultrasonic cleaner and it would take quite a lot of acetone to give a centimetre of liquid depth.
Not sure how well it would work placing a small plastic container ( or plastic ziplock bag ) filled with solvent, into the water bath in the cleaner - might be worth a try as it's vibration / shock waves that react with the grime agitating it. This should pass through a small thin walled container. Would need to use the right plastic or it could leech into the solvent.

[danmc82]

Would such a cleaner remove fingerprints and grease?

[sovereignsteve]

55 minutes ago, Pete said:

I have a basic jeweller's ultrasonic cleaner and it would take quite a lot of acetone to give a centimetre of liquid depth.
Not sure how well it would work placing a small plastic container ( or plastic ziplock bag ) filled with solvent, into the water bath in the cleaner - might be worth a try as it's vibration / shock waves that react with the grime agitating it. This should pass through a small thin walled container. Would need to use the right plastic or it could leech into the solvent.

You can put the coin in acetone in a smaller container and fill the bath with water, you just need to support the container on something solid. US baths work best if they are filled completely to the stated level.

Plastic will be no good for acetone, it'll dissolve or certainly soften most plastics.

 

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Added 0 minutes later...

28 minutes ago, danmc82 said:

Would such a cleaner remove fingerprints and grease?

being ultrasonicated in acetone or similar should do the job in theory.

[KevinFlynn]

For badly stained trade coins I am using a step method of soaking in a soapy solution (basic curd soap), then soaking in (boiling) hot distilled water, finally soaking in alcohol (isopropanol).

Leaving them to soak for a quarter of an hour each step or longer. No physical wiping or scratching. Just soaking and letting them dry. This works nicely.

[danmc82]

On 29/01/2019 at 14:25, KevinFlynn said:

For badly stained trade coins I am using a step method of soaking in a soapy solution (basic curd soap), then soaking in (boiling) hot distilled water, finally soaking in alcohol (isopropanol).

Leaving them to soak for a quarter of an hour each step or longer. No physical wiping or scratching. Just soaking and letting them dry. This works nicely.

What sort of coins have you cleaned using this method? Any Proofs?

[KevinFlynn]

No, no proofs, I am just stacking bullion level coins for gold content.

I never handled proofs, but I know that people are getting very nervous about handling them, so I assume they are better left alone...

I should maybe try one day and see if the right magnification shows any negative surface change, which would not be recognizable on a non proof after a century of handling.

I once came over a treatise on cleaning milk spots on silver with various methods and took from it that any mechanical influence will be visible under a magnifying glass, as will the influence of too sharp chemicals. That was when I began to think about the method of just using heat, and a fat as well as a water solving sollution.

[sovereignsteve]

6 hours ago, KevinFlynn said:

and a fat as well as a water solving sollution.

I assume English isn't your first language😉

I don't think fat is the right word but I get your point😀

I have a fair few loose proofs bought as bullion, sounds like I have a little project to get my teeth into🤔

[MickB]

I'll definitely be attempting to clean my half sovereign proof now after reading this thread although I'll look through my lesser value proof coins first to find a Guinea pig. Cheers

[Murph]

Funnily enough I’ve seen acetone for sale in plastic bottles before.  Maybe they just don’t expect you to keep it for very long so it won’t soften the plastic too badly in the time?   I can’t see them being ptfe or pp bottles as the bottle would be dearer than the acetone and they would be cheaper using glass or metal afaik.

[5huggy]

Acetone is and can be stored for up to 5/6 years in Plastic canisters/bottles -  as I have dealt with an awful lot of this through fibreglassing (Acetone is a major cleaning fluid for resin on tools and equipment)

In fact I still have a 4 litre canister / bottle (plastic) from 4 years ago - - totally unaffected!

[5huggy]

PS cheapest way to purchase acetone is from Fibreglass supplier companies  - - for those interested in obtaining some

[caloundracats]

Would meths be of any use? Thoughts?

[sovereignsteve]

4 hours ago, caloundracats said:

Would meths be of any use? Thoughts?

Ethanol and methanl, short chain alcohols, tend not to be much good as solvents. They have a restricted action on certain polar materials but you need to go past propanol to butanol and above to get any real action on organic materials.