NGC question

Cladiator

What causes the yellow discoloration of the normally white plastic inserts in NGC slabs? I've got a few NGC coins with this issue. If it's supposed to be sealed airtite for the coins protection..........???

coinfreak499

Plastic is porus (I think) so nothing is totally "airtite". PCGS slabs usually cause more milk spots than NGC and quicker. But i'm not sure how it is caused.

ER

You know they are not airtite.

thebeav

<< <i>You know they are not airtite. >>



Absolutely....Remember some of the threads about people that have stored their coins in the attic and such?

Paul

dorkkarl

uh, if your slabs are turning yellow, i'd hate to guess what the air in your house is doing to your lungs!

K S

Conder101

No he's right, there are a small numbr of NGC slabs out there where the insert is a yellowish creme color instead of the standard white. They were the result of a bad batch of plastic inserts and I have only seen them on one variety, either NGC 5 or 6 I don't remember which at the moment. I don't know if they were yellow from the start, or if the plastic missed the addition of a UV stablizer. (Many plastics will turn yellow if they are exposed to ultraviolet light. To prevent this a very small amount of a chemical is added to the molten plastic which keeps it from changing color.) The yellow tint to the slab isn't usually noticable on an individual slab, but if you put it next to a normal slab it is quite obvious.

Cladiator

excellent info, thanks conder!