PVC removal and NCS

drjules

HI

I have just taken my first dip into the "big coin league" with the purchase of a 1927 proof UK crown. Very nice coin with a significant amount of the proof finish intact but there is just a spot or two (less than pin head size) of PVC bloom on the high points. Please be gentle with me as I bought a raw coin, but it was a decent price compared to catalogue. Hey the coin even came with previous receipt and customs label from 1986 so I guess it has sat in that packaging for twenty years.

Two questions:

1. Will the PVC greenery get worse now the coin is out of the offending holder?
2. Has anyone here used NCS to have PVC damage removed? How does proof silver hold up to this type of cleaning.

BTW there is no way I'm going to try cleaning this myself!

Dr J

Preussen

1. PVC will eventually damage the surface of the coin, and should be removed as soon as possible.
2. I've personally never used NCS for PVC removal, but I understand they do so with good results. I've used "koinsolv" and acetone successfully, myself. Once done, there is no evidence of the removal (if it is done in time). Good Luck, - Preussen

MacCrimmon

pictures?

It may be best to have it conserved. If NCS thinks they can 'successfully' conserve the coin, they will. If not, you're out the exam fee. Pay for the guarantee at full book price. Also, no need to slab just because NCS conserved the coin......you can just send it to me.

drjules

Thanks for the advice.

You say you wouldn't use NCS, is this because of cost, not trusting someone else to clean your coin or that you can do the job yourself? Also how does acetone affect the proof finish?

Dr J

rhound1977

<< <i>1. PVC will eventually damage the surface of the coin, and should be removed as soon as possible.
2. I've personally never used NCS for PVC removal, but I understand they do so with good results. I've used "koinsolv" and acetone successfully, myself. Once done, there is no evidence of the removal (if it is done in time). Good Luck, - Preussen >>



Me too (#2 above)

drjules

I'll try to get some decent pics of the coin to show the PVC marks. I'm struggling with getting accurate colours and the correct white balance at the mo though

Dr J

ccrdragon

acetone will not affect the proof finish in any way and will dissolve any PVC on the surface of the coin - just make sure to use pure acetone and NOT finger nail polish remover because of the additives. I have dipped a number of proof silver coins and cannot tell the difference between the ones that have been dipped and the ones that have not.

Preussen

<< <i>Thanks for the advice.

You say you wouldn't use NCS, is this because of cost, not trusting someone else to clean your coin or that you can do the job yourself? Also how does acetone affect the proof finish?

Dr J >>



Sorry - I didn't mean to imply that I wouldn't use NCS for the PVC removal, I just never have. I used NCS once for conservation, on a coin that was already in a NGC slab...it made more sense than cracking it out, conserving it myself, and resubmitting.

In the early stages, PVC can generally be removed with a quick rinse in koinsolv or acetone. These are considered neutral solvents, and they don't affect the coin's surfaces (luster, toning, etc.). If you don't want to try it, I believe NCS would be the way to go. Let us know how it turns out? - Preussen

drjules

Hey just a thought. Does anyone have any (scrap) silver coinage with PVC damage I could hone my cleaning skills on before I take the plunge with the crown. I would happily pay melt value or just return the coin to you after I have seen the results.

Dr J