From the manufacturer:
Permanent, acid-free polyvinyl acetate formula that has lay-flat properties, dries clear and remains flexible. It is water soluble so it can be thinned easily to extend drying time. Formulated specifically for preservation materials to prevent them from becoming brittle with age. Use on paper, board, framing, collage and other porous surfaces. This package contains 8 oz. of adhesive. Made in USA.