Derek,
I don't really know what causes the bleeding. I believe that some of the plastic pages can speed up the process...but I don't remember the best kind of pages to have. I think I remember that the softer/more flexible holders and pages have more problems than the pages that are stiffer/more brittle. Hopefully someone else will come along with more information .

Most of our chips are in the cardboard holders in 12-pocket pages; some are in plastic flips in the 20-pocket pages. We don't have too many problems...then again, we have very few chipcos in our collection. If we had a lot of red Chipcos, I think I'd have 'em in airtight holders...just to be safe.