What is "active" PVC?

astrorat

There has been a good discussion on another thread about PVC residue on a coin encapsulated by a TPG. Rather than burying this question in that thread, I thought I would start a new thread.

What is "active" PVC?

How does one determine if PVC is "active" or "stable" on the surface of a coin?

amwldcoin

Active PVC is still slimey and moveable as opposed to being hard. Best way I know to say it.

ricko

I consider all PVC to be bad... and never really differentiate... If it is there, I would either remove it.... or, if on a coin for sale, avoid it. Cheers, RickO

Kkathyl

How do you remove it. Acetone? Is it the yellowish orange color I have seen? Can you add an illustration of both active and inactive to help educate us on the subject?

Thanks.

amwldcoin

Most PVC is Green....seems to be lighter in color the more active it is. When it turns hard it is usually Dark Green to Black. I suspect in it's earliest stages it is basically clear and gives a coin with luster a muted look. Acetone is the best thing to remove it with.

I'm sure there are other senarios but this is my observation from my experiences. I usually acetone most coins I submit for grading and you would be surprised how many coins have some PVC on them without being apparent!

@Kkathyl said:
How do you remove it. Acetone? Is it the yellowish orange color I have seen? Can you add an illustration of both active and inactive to help educate us on the subject?

Thanks.

Insider2

AFAIK, PVC usually starts out in a liquid state. Eventually, it becomes solid. PVC is usually appears as tints of green when hardened on the surface but I have seen a whitish haze also. If caught in time it will not damage the original microscopic surface! After that it depends on the amount of magnification.

Here are extreme examples:

On both of these the residue is soft enough to be "pushed" with a sharp sliver of a toothpick so will come right off with acetone. Our host can "fix" both of these. AFAIK, it is always "actively" harming the surface.

Broadstruck

I don't spend any time pondering if it's active or stable as any PVC is bad and prone to grow or worsen if not removed. I don't sweat PVC on Gold as it's inert to surface damage.

SkyMan

Active PVC is the kind that gets you off your couch to deal with it...

Unknown

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Insider2

@afford said:
What would be the thing on the surfaces of the coin, that looks like a couple of round mounded up nodules like the round nodules found in mineral like geode formations, and is emerald green or grass green in color. Looks to be solid and hard.

That would probably be active corrosion.

derryb

think of rust that never sleeps.

Insider2

I was able to find these. Go on to the ancient coin forum and you will see many, many better examples!

Kkathyl

Yikes