Why does Print File chooses polyethylene over polypropylene for their negative preservers?

For almost thirty years, Print File has manufactured negative preservers from polyethylene, an archival material proven safe for maximum long-term storage. We use polyethylene since the alternative polypropylene, creates a greater static charge, which consequently attracts more dirt and dust to the negative. In addition, dust and scratches are more noticeable on enlarged negatives; therefore, it is imperative that the conditions to reduce dust and scratches be controlled as much as possible. We optimize these conditions by manufacturing our negative preservers from polyethylene.