NextDayScience's parafilm is a flexible, waterproof, thermoplastic, sheet rolled with paper in between to prevent self-sticking. It is almost colorless, semi-transparent, tasteless, and odorless, is supplied 0.127mm (0.005") thick. It sticks firmly and quickly to itself, and is capable of closing petri dish edges or covering flask mouths or culture tubes. It has an outstanding resistance to alcohol, common acids, air and other gases, and slightly diluted alkalies. At 82°C - 93°C (180°F - 200°F), it becomes soft enough to "glue" together cloths, papers, leathers, etc. At 21°C (70°F), it can expand 200% and return partly to its normal size. It is packaged in handy dispenser cartons.