Coin trays and PVC

[Basileus Nikephoros Antialcidas]

Hello. I am moving my collection to PVC free flips. Before these I had my coins on a red velvet tray. The seller told me it was made by a good manufacturer (I will not tell the name as I think it is against the forums rules) which I know that they use safe materials. Now after a year it stuck to my head that as the tray was not on the brands website, maybe the seller by accident sold me a tray of an other brand. I don't know but can a velvet tray contain PVC, or PVC is used only to soften flips and also if it has, if I removed my coins and no damage is visible, could later be developed because they used to be in contact with that chemical, or because I removed them I saved them?

[Bill W4]

I don't think the tray would harm your coins.  I keep my coins in trays; tags, non pvc plastic on top and  coin on top of that.  Never had a problem.  Of course I don't have that many coins.

[cmcdon0923]

I believe that PVC is used in plastics as a softener, hence the reason that non-PVC flips are somewhat brittle.  Assuming so, I would doubt that they would add a softener to a plastic tray as it needs to be stiff.


Craig

[shanxi]

No, PVC is a very stable material, e.g. it is used for window frames. PVC makes no problems at all. Pure PVC will not damage your coins.

The problems are the plasticizers.  Plasticizers are used to improve the flexibility of PVC. High amounts (20% to 50%) of the low molecular weight substances are added to the PVC. Unfortunately these plasticizer do not stay within the polymer. After some years they tend to form sticky films on the surface, and on the coins if the material was used for coin flips.

Fortunately there are other materials which are flexible without plasticizers, and therefore without these problems.

[Basileus Nikephoros Antialcidas]

No, PVC is a very stable material, e.g. it is used for window frames. PVC makes no problems at all. Pure PVC will not damage your coins.

The problems are the plasticizers.  Plasticizers are used to improve the flexibility of PVC. High amounts (20% to 50%) of the low molecular weight substances are added to the PVC. Unfortunately these plasticizer do not stay within the polymer. After some years they tend to form sticky films on the surface, and on the coins if the material was used for coin flips.

Fortunately there are other materials which are flexible without plasticizers, and therefore without these problems.

Culd they be used on velvet trays?

[shanxi]

As far as I know, the trays are sometimes made of PVC (without plasticizers no problem). I don't think that the velevt inlays are made of PVC, but I don't know what material is used. (Polyacrylates?)

[Basileus Nikephoros Antialcidas]

As far as I know, the trays are sometimes made of PVC (without plasticizers no problem). I don't think that the velevt inlays are made of PVC, but I don't know what material is used. (Polyacrylates?)

Thank you very much. So I should not worry, either way I don't see any problem at all on the coins, and I will move them on PVC free flips. The only thing that buffles me is that I think that from the side that my silver coin are touching the surface of the velvet seem to have started getting a golden patina in the creases, very beautiful and natural patina, but I think it is more prominent from the side that they touch the velvet, could this be any bad indication, or my coins just started to patinate? But why it is not as prominent from the one side than the other?

[Callimachus]

Could the glue / rubber cement that holds the velvet down be giving off fumes or gasses that tarnish the coins?

[cmcdon0923]

How long have the coins that you think are beginning to tone been in these trays?

I have bright red copper tokens that have been sitting in some trays I made over 25 years ago that are almost as bright as the day I put them in. 


Craig

[Basileus Nikephoros Antialcidas]

How long have the coins that you think are beginning to tone been in these trays?

I have bright red copper tokens that have been sitting in some trays I made over 25 years ago that are almost as bright as the day I put them in. 


Craig

About a year. Maybe less. I don't know, maybe I bought them like this and don't remember the toning so well.

[PMah]

As Shanxi and Craig indicate, the question is about the chemical composition of the material.   "Velvet" is a description of the cut of the fiber of the underlying material, and it means the fiber was cut across the round end and the coin is in contact with those short ends, rather than the side of the fiber, as with a knitted sweater.  If the material was a natural fiber like wool or silk, the "Velvet" would be very soft, which is why rich people had "velvet" ermine robes and such, because it was exceptionally expensive to craft.   If the material was a modern hard plastic, it could be like a toothbrush.
  You would have to ask the manufacturer about the material.   I doubt any tray manufacturer in 2020 uses a natural fiber, so it all depends on the plastic. 

[cmcdon0923]

I doubt that any manufacturer would use a material the trays could affect the coins in that short a period of time.  I've had a few cleaned silver coins wrapped in relatively high sulfur content paper (brown paper bag) for a few years in an attempt to darken them, and they've hardly changed at all.


Craig

[Robert_Brenchley]

How fast coins tone depends very much on the local atmosphere. I find silver coins in flips tone in a couple of years, but I live a few hundred yards from a major road junction and I know the air round here's pretty polluted. If I still lived on the Cornish moors it would probably be a different story.