From the Manufacturer:
For all of its usefulness, acetate does cause a few headaches — ink that won't stay, a yellow or grayish cast to old acetate, edges that curl. The alternatives are expensive and sometimes just don't suit the purpose.
Dura-Lar is the acetate alternative. It combines the best features of Mylar® and acetate, and offers a variety of products so that you can purchase the film that suits your needs precisely. It is always consistent in color and overall clarity, and won't discolor with age.
Dura-Lar is archival quality, safe for overlaying artwork, and it lays flat. It will remain dimensionally stable for as long as you need.
Designed for layouts, color separations, protective covering, or overhead transparencies.