Archival Methods Slide File Box 11-3/8x2 x 2-3/8", 3 Pack, Tan Made from fully bleached, high alpha cellulose pulp. It does not contain any post consumer waste recycled pulp. Paper is free of metal particles, waxes, plasticizers, residual bleach, peroxide, sulfur content is less than 0.0008% reducible sulfur. The lignin content is measured by the phloroglucinol test with a Kappa number of 5 or less. Metallic Impurities, Iron will not exceed 150 ppm and copper shall not exceed 6 ppm. No optical brightening agents are used in the pulp. The paper contains a minimum of 3% calcium carbonate (CaCO3) with a pH range 8-9.5