All three of our poly materials have passed the Photo Activity Test. This test was run by an independent lab certifying that our poly materials are safe for long-term storage.
 (PE) is a by-product of natural gas. It is a soft clear material that has some give to it. It has excellent contact clarity. 3mil is by far the most popular thickness. Our polyethylene is made from 100% pure-virgin material. Use for Long-term storage.
POLYPROPYLENE (PP) is a crystal-clear, high sheen, crisp material. We use bi-oriented polypro which means that when the material is made, it is stretched in both directions so that in time it will not "pucker" (decreasing the clarity). Use for Long-term storage.
ARCHIVAL POLYESTER (PET) (Mylar) is an inert material of the highest clarity. We use DuPont inert Melinex® or a suitable equivalent. Polyester (Mylar) will not discolor, damage, or adhere to items placed inside it. It is a sturdy film that beautifully displays, timelessly protects, and gives extra support to fragile documents. Used by the Library of Congress. Indefinite Storage.