UNCLEANED COINS

[DimitriosL]

Greetings, recently i resumed my hobby of cleaning roman bronzes. I ve come to realize that it not lucrative but I still enjoy the process. Does anyone know a good and active forum for instructions and questions about coin cleaning. There are some that are quite tricky and would like tips and guidance. 

[GordianAppreciator101]

7 hours ago, DimitriosL said:

Greetings, recently i resumed my hobby of cleaning roman bronzes. I ve come to realize that it not lucrative but I still enjoy the process. Does anyone know a good and active forum for instructions and questions about coin cleaning. There are some that are quite tricky and would like tips and guidance. 

You should join the AncientCoins discord server, the mods just opened a "Cleaning Coins" tab this week. 

(Not sure if this counts as advertising, plenty of people came from that discord when the forum was opened. LMK if it's not allowed)

Edited April 12, 2023 by GordianAppreciator101
Typo

[hotwheelsearl]

I'm pretty experienced, ask away

[DimitriosL]

56 minutes ago, hotwheelsearl said:

I'm pretty experienced, ask away

I am dealing with some confusing cases regarding the patina on both copper and silvered issues. I don't know what to make of the surface whether it is oxidation, deposits , patina, silver etc. Unfortunately, I am away for the Easter and can't provide photos yet. I would also appreciate your input on cleaning tools. I only use the basic ( dental picks, toothpicks, glassfiber brushes, x5 magnification) but I would like to expand my arsenal. Also,have you ever used cleaning mixes( like mint state restoration)?

 

 

 

 

[hotwheelsearl]

A lot of practice helps you determine what kind of encrustation you have, and how to remove it. I'm a big proponent of chemicals.

In general:

brown/flaky/dirt colored on bronze - use sodium hydroxide
red/orange/rust colored on bronze - use sodium thiosulfate
blue/green on bronze - use acetic acid (vinegar)
black on silver - use sodium thiosulfate

Vinegar is usually a last resort, as it will almost certainly strip patina. however, if the coin is already overcleaned to begin with, then sometimes it's your last option. Depending on the composition of the coin, ie bronze vs copper vs brass vs orichalcum, vinegar may or may not be a great option, though. For example, vinegar was what brought a sestertius of Trajan back to life.

Silver is pretty resistant to most of patina-stripping compounds, iff its quite pure silver. I still tend not to subject silver to vinegar since it will dissolve it away pretty quick. One of the simplest, and most dramatic methods of cleaning silver is simple sodium thiosulfate. This tends to leave the patina mostly alone, while removing all of the black horn silver. 

It's all very conditional, and pics are always helpful to try to figure out a game plan. 

As for tools - I only use a dental pick for the most part. The way I see it, if a gauntlet of chemicals and incredibly high point-based pressure from a pick doesn't do the trick, nothing will.

Also, I sometimes use Jax Patina Restorer and Renaissance Wax. Jax is good if you've stripped a coin to bare metal; sometimes you end up with coin that looks almost pink!

Depending on the surface you end up with, Renaissance Wax is good to even out micro-pitting and even out the color. However, it gives a rather glossy finish that some collectors don't like. You can counter this by treating with Ren Wax, letting it sit overnight, and then dunking it in some mineral spirits. This will remove some, but not all, of the Ren Wax.

That's all I got for now

 

[Nerosmyfavorite68]

What would you do with something like this?  The horn silver is rather thick on the reverse.  What kind of mix would be used (how diluted)? How long would it be dunked in there?  What then?  A brush?  How does one stop the process?  How about drying it?

This came from a hoard which had fairly many pieces with more detail than usual.  However, the cleaning job wasn't great; scratches and horn silver.  The non-horn silver parts are shiny, so something was done.

However, the great majority of uncleaneds I buy are because I found those particular ones to be more interesting that way.  Cleaning those particular ones, even if I managed not to botch it, would just reveal a mundane or decrepit coin.  I enjoy having a few different types as uncleaneds.

I found these to be much more interesting this way.  I don't see uncleaned Sassanians too often.

[DimitriosL]

9 hours ago, hotwheelsearl said:

A lot of practice helps you determine what kind of encrustation you have, and how to remove it. I'm a big proponent of chemicals.

In general:

brown/flaky/dirt colored on bronze - use sodium hydroxide
red/orange/rust colored on bronze - use sodium thiosulfate
blue/green on bronze - use acetic acid (vinegar)
black on silver - use sodium thiosulfate

Vinegar is usually a last resort, as it will almost certainly strip patina. however, if the coin is already overcleaned to begin with, then sometimes it's your last option. Depending on the composition of the coin, ie bronze vs copper vs brass vs orichalcum, vinegar may or may not be a great option, though. For example, vinegar was what brought a sestertius of Trajan back to life.

Silver is pretty resistant to most of patina-stripping compounds, iff its quite pure silver. I still tend not to subject silver to vinegar since it will dissolve it away pretty quick. One of the simplest, and most dramatic methods of cleaning silver is simple sodium thiosulfate. This tends to leave the patina mostly alone, while removing all of the black horn silver. 

It's all very conditional, and pics are always helpful to try to figure out a game plan. 

As for tools - I only use a dental pick for the most part. The way I see it, if a gauntlet of chemicals and incredibly high point-based pressure from a pick doesn't do the trick, nothing will.

Also, I sometimes use Jax Patina Restorer and Renaissance Wax. Jax is good if you've stripped a coin to bare metal; sometimes you end up with coin that looks almost pink!

Depending on the surface you end up with, Renaissance Wax is good to even out micro-pitting and even out the color. However, it gives a rather glossy finish that some collectors don't like. You can counter this by treating with Ren Wax, letting it sit overnight, and then dunking it in some mineral spirits. This will remove some, but not all, of the Ren Wax.

That's all I got for now

 

Wow man you know your stuff! Thank you so much!! I soon a I get some pics I m gonna post them.

[DimitriosL]

13 hours ago, hotwheelsearl said:

I'm pretty experienced, ask away

I ve also come across a case similar to this( a denarius). Pretty much the same surface. I would like to highlight some details on the portrait like hair, eyes etc that are still covered with black tarnish/horn silver.? From what I ve read lemon juice is a safe choice applied locally. Do you have anything else in mind. 

I post a coin that is pretty close to my case and one that i lost in a recent auction😪

[Nerosmyfavorite68]

Oh, and there's also some general cleaning videos on youtube. 

I also have a question about uncleaned silver.  Do most come out of the ground looking like this?  (random example) https://www.vcoins.com/en/stores/zurqieh/171/product/parthian_kingdom_silver_drachm__choice_as_found/1588658/Default.aspx

Should I steer away with the ones with BD?  I do for AE's.  I'm not sure of purity of later Parthian silver.  Will it hurt decent silver?

I wasn't going to get that particular one.  It has too many encrustations.  There are a few with mint green highlighting and no encrustations.  Will encrustations build if nothing's done?

Per my uncleaned contents, I'd like to clarify that I wasn't running down the practice of cleaning. I'm attempting to build an array of different type of uncleaneds, for educational purposes.

[Cordoba]

10 hours ago, Nerosmyfavorite68 said:

What would you do with something like this?  The horn silver is rather thick on the reverse.  What kind of mix would be used (how diluted)? How long would it be dunked in there?  What then?  A brush?  How does one stop the process?  How about drying it?

This came from a hoard which had fairly many pieces with more detail than usual.  However, the cleaning job wasn't great; scratches and horn silver.  The non-horn silver parts are shiny, so something was done.

However, the great majority of uncleaneds I buy are because I found those particular ones to be more interesting that way.  Cleaning those particular ones, even if I managed not to botch it, would just reveal a mundane or decrepit coin.  I enjoy having a few different types as uncleaneds.

I found these to be much more interesting this way.  I don't see uncleaned Sassanians too often.

Roerbakmix posted this tutorial using sodium thiosulfate on cointalk https://www.cointalk.com/threads/how-to-remove-encrustation-from-r-r-coin.348784/#:~:text=Well-Known Member-,Thanks,-%40TIF. I agree

[madhatter]

Hello All,

any advice with cleaning this Antoninus Pius would be much apreciated!

The green encrustations are very, very hard. The coin is curently soaked in deionised water, for more than a month, with almost no result on the green stuff.

[seth77]

On 4/13/2023 at 9:18 AM, Nerosmyfavorite68 said:

What would you do with something like this?  The horn silver is rather thick on the reverse.  What kind of mix would be used (how diluted)? How long would it be dunked in there?  What then?  A brush?  How does one stop the process?  How about drying it?

This came from a hoard which had fairly many pieces with more detail than usual.  However, the cleaning job wasn't great; scratches and horn silver.  The non-horn silver parts are shiny, so something was done.

However, the great majority of uncleaneds I buy are because I found those particular ones to be more interesting that way.  Cleaning those particular ones, even if I managed not to botch it, would just reveal a mundane or decrepit coin.  I enjoy having a few different types as uncleaneds.

I found these to be much more interesting this way.  I don't see uncleaned Sassanians too often.

Leave them be they look great as is.

[shanxi]

13 hours ago, madhatter said:

Hello All,

any advice with cleaning this Antoninus Pius would be much apreciated!

The green encrustations are very, very hard. The coin is curently soaked in deionised water, for more than a month, with almost no result on the green stuff.

If your coin is a fouree, I wouldn't remove it. Chances are that if you remove the apparently stable malachite, you will end up with a hole going down into the copper core.

If it's really just a crust on good silver (which I don't think it is), it can be easily removed with EDTA: I did that with this Faustina.

Faustina Minor
AR-Denar, Rome
Obv.: FAVSTINA AVGVSTA. Draped bust right.
Rev.: MATRI MAGNAE, Cybele seated right with branch and drum, behind her a lion.
Ag, 3.83g
Ref.: RIC -, CRE- (this type with Cybele right is only know for Aurei)

cleaned and uncleaned
uncleaned picture: Kölner Münzkabinett

Edited April 14, 2023 by shanxi

[DimitriosL]

I also bought this coin for a friend in a previous auction for a low price. I love the portrait but I would prefer if the rust(?) was gone. Does anyone know if this is possible, to remove colouring like that?

[hotwheelsearl]

1 hour ago, DimitriosL said:

I also bought this coin for a friend in a previous auction for a low price. I love the portrait but I would prefer if the rust(?) was gone. Does anyone know if this is possible, to remove colouring like that?

This almost looks like the silver has worn away exposing a copper core.

[DimitriosL]

20 minutes ago, hotwheelsearl said:

This almost looks like the silver has worn away exposing a copper core.

I saw it in person. It's more like an transparent hue and you can see silver beneath so in guessing some kind of rust residue.

[hotwheelsearl]

1 hour ago, DimitriosL said:

I saw it in person. It's more like an transparent hue and you can see silver beneath so in guessing some kind of rust residue.

Are you sure the silver layer is not on top? You can often have silvered coins that look like there's rust, but it's just the surface layer wearing away. To be fair, Philip I tended not to mint silvered coins, so you may be right after all.

 

If it's truly a layer of oxidized rust, then sodium thiosulfate will get rid of it, pronto.

[madhatter]

11 hours ago, shanxi said:

If your coin is a fouree, I wouldn't remove it. Chances are that if you remove the apparently stable malachite, you will end up with a hole going down into the copper core.

If it's really just a crust on good silver (which I don't think it is), it can be easily removed with EDTA: I did that with this Faustina.

Faustina Minor
AR-Denar, Rome
Obv.: FAVSTINA AVGVSTA. Draped bust right.
Rev.: MATRI MAGNAE, Cybele seated right with branch and drum, behind her a lion.
Ag, 3.83g
Ref.: RIC -, CRE- (this type with Cybele right is only know for Aurei)

cleaned and uncleaned
uncleaned picture: Kölner Münzkabinett

Well, judging from my pics it does looks bit questionable - fouree or silver. In hand, I would say it is solid silver, and I want to see it cleaned - hoping that underneath the green crystalisation will pop up an uncoroded surface. On the obverse, I managed to remove small green spots, same hard crystalisation type, and it went fine. Still looking for the best method  - if possible would like to keep the tonning. How exactly to use EDTA - should it stay in for couple of minutes/hours, or just a drops on the area i want to soften?

Edited April 14, 2023 by madhatter

[DimitriosL]

9 minutes ago, hotwheelsearl said:

Are you sure the silver layer is not on top? You can often have silvered coins that look like there's rust, but it's just the surface layer wearing away. To be fair, Philip I tended not to mint silvered coins, so you may be right after all.

 

If it's truly a layer of oxidized rust, then sodium thiosulfate will get rid of it, pronto.

Im positive it's rust, also you are right about Philip. So pretty much same process as cleaning horn silver?

[hotwheelsearl]

1 hour ago, DimitriosL said:

Im positive it's rust, also you are right about Philip. So pretty much same process as cleaning horn silver?

I would imagine so, thiosulfate works wonders on rust on non-silver coins, so I would think it would work on silver coins.

[Nerosmyfavorite68]

17 hours ago, seth77 said:

Leave them be they look great as is.

I find myself returning often to that Hexagram well.  There must have been a large hoard.  I scooped up most of the 'best' ones.

[shanxi]

12 hours ago, hotwheelsearl said:

I would imagine so, thiosulfate works wonders on rust on non-silver coins, so I would think it would work on silver coins.

Thiosulfate is one of the best complexants for Ag+ ions, forming Ag[S2O3]3- complexes. It is perfect for AgCl, good for Ag2O, but will not be enough for Ag2S (silversulfide).

 

 

Edited April 15, 2023 by shanxi

[shanxi]

12 hours ago, madhatter said:

How exactly to use EDTA - should it stay in for couple of minutes/hours, or just a drops on the area i want to soften?

EDTA is a complexant for M2+ ions, like Ca2+, Fe2+ etc.. On silver coins it can remove Cu2+ without much effect on the silver patina.

But as I said I wouldn't use it on your coin. I still think that it is a fouree and you don't know how deep the Malachite goes. 

[expat]

Is there a generally accepted dilution for sodiumhydroxide as a test or starting point for bronze-copper coins?

[hotwheelsearl]

3 hours ago, expat said:

Is there a generally accepted dilution for sodiumhydroxide as a test or starting point for bronze-copper coins?

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