Pete; I too suspect that the cause of damage shown to your chips is a result of PVC action. As others have mentioned, there was a rather long, very educational thread on this subject some time ago that could be searched in the archives. For those who have commented on the comparative expense of using airtites ... a cheaper and safer alternative would be the old style fold-over cardboard 2x2 holder with the mylar windows. They now come with a double stick surface instead of stapling closed, but the holder will be destroyed if one attempts to re-open it. They can not usually be resealed once torn apart.... but the stapled variety is very inexpensive.