I have had these silver/copper/zink coins in an Optima M storage sheet for over 20 years. Now the plastic is starting to turn yellow. anyone any suggestions why?
(http://i457.photobucket.com/albums/qq296/hannu2009/img06232015_0001_zpsvrxbfngt.jpg) (http://s457.photobucket.com/user/hannu2009/media/img06232015_0001_zpsvrxbfngt.jpg.html)
eeeekkkkk!!!!!!!!!!!!!!!!
Are they sitting against paper? I assume the sheets aren't PVC.
Really strange, the yellowing parts are the sliding inserts and i can have one yellow and one clear in one sheet, also there is no consistency if I have an original black separator sheet against it. Also it is not dependent on the coin metal type, I have clear and yellowish sheets with same silver coins. It has to be the plastic compound gone wrong in some inserts. There are only original components in that folder, no paper or other sheets.
The coins are not affected.
I have to pull them out and put in my new cardboard holders and mylar sheets. That'll be the next project.
Plastics can be like baking a cake, sometimes it looks good but does not taste right. I used to work as an engineer for a big Japanese company making air conditioners. one year we had a batch of name badges that after about 6 months started to drip off the indoor unit onto the floor like honey. Something went wrong with the compound in the manufacturing process and the plastic started to "melt" in room temperature.
This is the reply I got from the manufacturers about these pages:
on the pages with sliding inserts there is a combination of materials:
- the inside (which is in contact with the collectible) is made of rigid, unplastizised PVC;
- the outside is made of soft vinyl (PVC) because it must have the flexibility to handle the sliders.
Although, they have changed color, it is the appearance of the item, and will not affect the coins.
In my opinion, even if the view that the rigid PVC is safe is correct, the fumes from the outer pages pose a risk to anything exposed to them, including other coins which may be nearby. I feel they should come with a warning.