Our 100% cotton fiber base is a xerographic laser/LED vellum transparentized with environmentally friendly solvents, and surface treatment is applied to produce an extremely smooth faced sheet with excellent pickup and minimal solvent migration. Lines and graphics come out clear, sharp, and dense on our vellum. Modern technology has created our xerographic laser/LED vellum. Lines and graphics come out clear, sharp, and dense. 100% cotton means that our vellum will stand up to long term archiving needs. Properties Thickness: 20Lb / .75gm Opacity: 50% Best Printing Remember to always print on the preferred side of the media. The preferred side is always on the outside of the roll unless otherwise noted. Handle print media by the edges to prevent dirt and oils from contaminating the print area. Best results are achieved when operating at 65-85F degree and 25-70% humidity. Storage Always store laser/xerographic media in a cool dry area. If storage conditions vary from printing conditions, allow the product to adjust before beginning to print. Archiving 20Lb Transparentized Vellum is produced from 15% cotton fiber.