Coin Encapsulatation

[ozjohn]

I have a 1922 PCGS graded MS63 halfcrown that seems to have a very uneven tone. My question is since owning this coin the toning seems to have increased disfiguring the coin further.

I am wondering if this may be due to impurities in the plastic capsule and if anyone else ha had this issue.

Any comments please.

[Rob]

It could also be due to silver dip. I have seen fairly rapid toning build up on some dipped coins over a period of a few years, which I have assumed was due to residual chemical deposits on the surface. This is noteworthy because the TPGs don't seem to view dipping as cleaning, but there is no reason to assume that encapsulation would inhibit the reaction.

[The Coinery]

You would hope that the TPG's did their home work and use a plastic which is inert to metal.

Due to the inherent undulation of the raised areas of a coin V the smooth internal face of the coin there is going to be air in the capsule.

I have seen on two coin verdigris increase in size during their time in slabs.

If a chemical reaction was already occurring when the coin was inserted then there is no reason why the reaction would stop.

If you are concerned about the reaction enough to remove the coin to save it them possibly you could test the coins pH on its surface and then dunk and soak the coin in an equally alkali pH solution which logically could counter the reaction.

I have never tried this and I would naturally recommend you attempt this upon a worthless coin.

In the past I have used my Wife's ear buds and hot water to remove gunk and clag from my coins.

I have copied this bit which is underlined:

" Blue litmus paper turns red under acidic conditions and red litmus paper turns blue under basic or alkaline conditions, with the color change occurring over the pH range 4.5–8.3 at 25 °C (77 °F). Neutral litmus paper is purple."

Observing the colour of the litmus paper would not be an exact science but by getting the colour a near to purple as you could is at least reducing the reaction and thus slowing it down so staving off the reaction speed if not stopping it.

In England we have a medical liquid called TCP which has helped me with coins in the past. Once I have removed the gunk / clag I rinsed in boiling water very thoroughly then soaked in deionized water.

Off subject but I have had some success removing verdigris by folding toilet roll several times then putting in a plastic container with the coin on the paper then filling with water then leaving in the freezer for a few days. What I did next was to remove the lump of ice which was the size of a Hockey Puck put it in a tea towel and the I hit the ice with a hammer just once. Sounds brutal but on more than half of these attempts the verdigris ended up in the ice.

Obviously try this out on a worthless coin a few times first.

 

[Mr T]

16 minutes ago, The Coinery said:

You would hope that the TPG's did their home work and use a plastic which is inert to metal.

Due to the inherent undulation of the raised areas of a coin V the smooth internal face of the coin there is going to be air in the capsule.

I have seen on two coin verdigris increase in size during their time in slabs.

If a chemical reaction was already occurring when the coin was inserted then there is no reason why the reaction would stop.

If you are concerned about the reaction enough to remove the coin to save it them possibly you could test the coins pH on its surface and then dunk and soak the coin in an equally alkali pH solution which logically could counter the reaction.

I have never tried this and I would naturally recommend you attempt this upon a worthless coin.

In the past I have used my Wife's ear buds and hot water to remove gunk and clag from my coins.

I have copied this bit which is underlined:

" Blue litmus paper turns red under acidic conditions and red litmus paper turns blue under basic or alkaline conditions, with the color change occurring over the pH range 4.5–8.3 at 25 °C (77 °F). Neutral litmus paper is purple."

Observing the colour of the litmus paper would not be an exact science but by getting the colour a near to purple as you could is at least reducing the reaction and thus slowing it down so staving off the reaction speed if not stopping it.

In England we have a medical liquid called TCP which has helped me with coins in the past. Once I have removed the gunk / clag I rinsed in boiling water very thoroughly then soaked in deionized water.

Off subject but I have had some success removing verdigris by folding toilet roll several times then putting in a plastic container with the coin on the paper then filling with water then leaving in the freezer for a few days. What I did next was to remove the lump of ice which was the size of a Hockey Puck put it in a tea towel and the I hit the ice with a hammer just once. Sounds brutal but on more than half of these attempts the verdigris ended up in the ice.

Obviously try this out on a worthless coin a few times first.

 

The neutralising the pH sounds pretty risky - unless you know your chemistry very well I think it has the potential to go very wrong.

The ice method actually sounds half-decent though.

Edited October 16, 2016 by Mr T

[The Coinery]

The pH is just the strength of the acidity / alkalinity.

I am assuming (ass U me) that silver dip is an acid but whether it is or not providing the opposite on the pH table is used then there should be no problem.

There are brands of soap with neutral pH which are good for the skin. I have use Imperial Leather for 50 years to my knowledge and my face has not dropped off.

As I am sure you have I have some really crappy coins that have been dipped and I will have a play and report back.

My "Ice Hockey Puck" method does give results. BUT just give it ONE crack with a hammer.

We did try melting the "puck" but the results we not as good.

Let me know if you have a go.

[Sword]

11 hours ago, ozjohn said:

I have a 1922 PCGS graded MS63 halfcrown that seems to have a very uneven tone. My question is since owning this coin the toning seems to have increased disfiguring the coin further.

I am wondering if this may be due to impurities in the plastic capsule and if anyone else ha had this issue.

Any comments please.

It is inconceivable that any TPG would use a plastic that gives off acidic fumes. Otherwise the company will close in no time. This is from the PCGS website "Proprietary polymer formula with embedded PCGS identifiers: Made from a new blend of crystal-clear, scratch-resistant plastic that's tested to be 99.99% chemically-inert. The chemical formula contains PCGS-specific additives that can be detected using a special handheld device. These sturdier, tamper-evident holders have no edge seam, are virtually airtight and will provide even more protection against potential environmental damage to coins."

Simply encapsulating a coin does not stop surface reactions already in progress though.

On a different note, it highlights the obvious fact that the grade of a TPG doesn't correlate to eye appeal. 

 

 

[PWA 1967]

I suggest you wrap it in toilet paper .

Freeze it for a few days.

Take it out of the freezer then throw all the lot away as its horrible 

[copper123]

37 minutes ago, PWA 1967 said:

I suggest you wrap it in toilet paper .

Freeze it for a few days.

Take it out of the freezer then throw all the lot away as its horrible 

LOL

[VickySilver]

I suppose not really adding much than a seconding. This is the type of thing that happens as a progression of reaction due to residuals on the surface of the coin & most likely culprit being incomplete dipping wherein either dip residual is allowed to act OR that material the dip was to remove was not itself completely removed and is reacting anew on the surface. Another alternative is that the environment may still be penetrating the slab in the form of moisture or gasses.

I do not suspect the polymer plastic of the slab itself - this is a very hard material that seems to lack the plasticiser we see in the PVC-laden flips. It breaks with very "hard" delineated fractures.

[ozjohn]

The coin seems to have been encapsulated some time ago and on checking the PGCS site there is a record of the coin but no photo available. I agree it is unlikely that the plastic would affect the coin however perhaps it was contaminated prior to encapsulation. I have no idea if these TPG companies degrease the coin with acetone or similar prior to encapsulation. May be it's time to find out how to remove the coin from its capsule and dip it in bicarb.of soda and aluminum foil to improve its eye appeal rather than follow PWA 1967's unhelpful comments.

[PWA 1967]

1 hour ago, ozjohn said:

The coin seems to have been encapsulated some time ago and on checking the PGCS site there is a record of the coin but no photo available. I agree it is unlikely that the plastic would affect the coin however perhaps it was contaminated prior to encapsulation. I have no idea if these TPG companies degrease the coin with acetone or similar prior to encapsulation. May be it's time to find out how to remove the coin from its capsule and dip it in bicarb.of soda and aluminum foil to improve its eye appeal rather than follow PWA 1967's unhelpful comments.

On a more serious note 

Should you decide to use cotton buds there is currently on ebay a seller who has boxes of five thousand.

You may need a few 

Edited October 17, 2016 by PWA 1967

[ozjohn]

Coin removed from capsule and dipped in Bicarb. of Soda plus aluminium foil. Process seemed to be very slow perhaps on account it's a 50% silver coin. I'm reasonably happy with the result. It's certainly much better than before

[Sword]

6 hours ago, ozjohn said:

Coin removed from capsule and dipped in Bicarb. of Soda plus aluminium foil. Process seemed to be very slow perhaps on account it's a 50% silver coin. I'm reasonably happy with the result. It's certainly much better than before

It's certainly a big improvement!

[Peter]

WOW much better.

[Mr T]

On 16/10/2016 at 6:58 PM, The Coinery said:

The pH is just the strength of the acidity / alkalinity.

I am assuming (ass U me) that silver dip is an acid but whether it is or not providing the opposite on the pH table is used then there should be no problem.

That's true but the reaction between an acid and a base will produce a by-product and that's the risky bit in my opinion.

[VickySilver]

Hmmm, seem to recall the stronger acid "donating" H+ to the weaker acid (i.e. pushing it onto the weaker). What does that mean? Very strange reactions with some of these organic acids, where they will combine with each other, have polar moments and all kind of craziness in that a part of the molecule may be differentially charged. So which is reacting with the metal and are there any irreversible reactions taking place? I don't know, just that its not straight acid/base reactions...

[Mr T]

My chemistry knowledge never went that far but yeah, there's probably quite a bit going on - likewise the chemistry of an alloy is probably not straight-forward.