How to clean gold coin

[Colin.b]

Hi i was just wondering what people do to clean a gold coin, would you just give it a clean in soapy water, or would you use something like a jewellers polishing cloth.

[Sirbleepsalot]

Gently, depends on it's condition, pics will help

[Colin.b]

Gently, depends on it's condition, pics will help

Couple of pics

[Mega B]

I only have cleaned my gold hammered and milled coins under the cold tap and with the softest of toothbrushes going.....never ever use abrasives or anything like that as you will kill the condition of the coin or gold artefact.

[Sirbleepsalot]

Couple of pics

Can't see 'em.

[Colin.b]

Can't see 'em.

Uploaded pics twice but not showing for some reason

[Colin.b]

I only have cleaned my gold hammered and milled coins under the cold tap and with the softest of toothbrushes going.....never ever use abrasives or anything like that as you will kill the condition of the coin or gold artefact.

Thanks for the advice

[Sirbleepsalot]

Uploaded pics twice but not showing for some reason

Regardless, if it only has bullion (scrap) value a gentle soapy rub, historical or numismatic value, distilled water or leave alone. It would be nice to have your dilemma!

[Colin.b]

Regardless, if it only has bullion (scrap) value a gentle soapy rub, historical or numismatic value, distilled water or leave alone. It would be nice to have your dilemma!

Thanks, Ive only had one lol

[sabie 01]

Hi i was just wondering what people do to clean a gold coin, would you just give it a clean in soapy water, or would you use something like a jewellers polishing cloth.

Cleaning a gold coin.
When presented with this George III Gold guinea dated 1777.

gg crud 01a.jpg

Heavily covered in concretion. A lot of our artefacts recovered from the Halsewell shipwreck would be covered in concretion.

First I went straight to the Reverse Electrolysis, using a battery charger.
Image of my setup.

elec01a.jpg

After trying this for short periods of time (10 mins at a time) to no effect. I then left it cooking for an hour with plenty of Soda Crystals. Still to a little effect.

What comes next is not for the Faint hearted.

Having worked in the construction/maintenance business for over 30 years, I remember using a solution for cleaning set concrete off of tools and equipment and it worked very well.

Rummaged around the workshop and found some, read the label and discovered it was HYDROCHLORIC ACID.

Big decision, am I going to try my coin cleaning in this acid?

I decided to bite the bullet and give it a try.
Half glass tumbler of acid, as soon as I took the top off the bottle the fumes were quite toxic so took it outside of the workshop.
Popped the concreted coin in and it started to fizz and bubble straight away.
Gave it ten minutes and checked to see what damage I was doing.
Drained off the acid and washed the coin in warm soapy water, to my surprise the concretion had fallen off and the coin was intact.
Still traces of crud so popped it back in the acid for a further 30 mins or so.
Again drained off the acid and gave it a good wash as before and this is the end result.

GG-1777.jpg

Owing to the vast expense of our diving operations we had to sell some of our artefacts to off set the costs.
This Gold Guinea sold for just over one thousand on a well known internet auction site. With a certificate of authenticity. (COA)

So my cleaning method did not affect the value of the coin.
Bering in mind that my Gold Guineas are 22ct gold.

After the success of this cleaning op, I went ahead and ordered 20 gallons of Hydrochloric Acid from a chemical firm. Most of our artefacts have been cleaned with this acid in one form or another. Finds/artefacts can be viewed on my thread at Halsewell the shipwreck
Obviously the acid can be diluted to a weaker mix by adding water.


(Note. I take no responsibility for anyone trying this method of cleaning on their muddy field finds. It is all trial and error.)

Warning

Is hydrochloric acid safe for humans?
Hydrochloric acid in contact with skin or other tissues can cause chemical burns that can be severe. Hydrochloric acid in the eyes can cause blindness. The severity of the burns depends upon the concentration of the acid and the amount of time it is left in contact with the tissues.

[Colin.b]

Cleaning a gold coin.
When presented with this George III Gold guinea dated 1777.

gg crud 01a.jpg

Heavily covered in concretion. A lot of our artefacts recovered from the Halsewell shipwreck would be covered in concretion.

First I went straight to the Reverse Electrolysis, using a battery charger.
Image of my setup.


elec01a.jpg

After trying this for short periods of time (10 mins at a time) to no effect. I then left it cooking for an hour with plenty of Soda Crystals. Still to a little effect.

What comes next is not for the Faint hearted.

Having worked in the construction/maintenance business for over 30 years, I remember using a solution for cleaning set concrete off of tools and equipment and it worked very well.

Rummaged around the workshop and found some, read the label and discovered it was HYDROCHLORIC ACID.

Big decision, am I going to try my coin cleaning in this acid?

I decided to bite the bullet and give it a try.
Half glass tumbler of acid, as soon as I took the top off the bottle the fumes were quite toxic so took it outside of the workshop.
Popped the concreted coin in and it started to fizz and bubble straight away.
Gave it ten minutes and checked to see what damage I was doing.
Drained off the acid and washed the coin in warm soapy water, to my surprise the concretion had fallen off and the coin was intact.
Still traces of crud so popped it back in the acid for a further 30 mins or so.
Again drained off the acid and gave it a good wash as before and this is the end result.


GG-1777.jpg

Owing to the vast expense of our diving operations we had to sell some of our artefacts to off set the costs.
This Gold Guinea sold for just over one thousand on a well known internet auction site. With a certificate of authenticity. (COA)

So my cleaning method did not affect the value of the coin.
Bering in mind that my Gold Guineas are 22ct gold.

After the success of this cleaning op, I went ahead and ordered 20 gallons of Hydrochloric Acid from a chemical firm. Most of our artefacts have been cleaned with this acid in one form or another. Finds/artefacts can be viewed on my thread at Halsewell the shipwreck
Obviously the acid can be diluted to a weaker mix by adding water.


(Note. I take no responsibility for anyone trying this method of cleaning on their muddy field finds. It is all trial and error.)

Warning

Is hydrochloric acid safe for humans?
Hydrochloric acid in contact with skin or other tissues can cause chemical burns that can be severe. Hydrochloric acid in the eyes can cause blindness. The severity of the burns depends upon the concentration of the acid and the amount of time it is left in contact with the tissues.

Wow that really is unbelievable. I would of though the acid would of ruined the coin.

[Boulton800]

Gold is an amazing metal, it will not react to most acids or alkalises. Hydrochloric acid only reacts with gold if mixed with nitric acid.

Have a Google. Gold is one of the most stable elements on the planet. . Just remember it’s soft so don’t be rough with it.

[Fusion]

"I remember using a solution for cleaning set concrete off of tools and equipment and it worked very well. I rummaged around the workshop and found some, read the label and discovered it was HYDROCHLORIC ACID."

Hydrochloric acid is also known as Muriatic acid. It is sold in high strength to the building trade as "brick cleaning acid", but also used for cleaning swimming pools. Both of these tend to be supplied in large quantities, like 5 litre, 25 litre bottles.
For a small volume, one product that works much the same is Harpic Power Plus, which is mostly strong hydrochloric acid ( 5% concentration ), with a few other ingredients ( eg. perfume, viscosity modifier to make it gloopy ):
https://www.harpic.co.uk/products/toile ... ower-plus/