cork stopper The cork material has many peculiarity that can not be substituted by the high polymer synthesis material: low specific gravity, good elastics, non-permeability , non-air-leakage, low burning point, and resistance against corrossion of microbes and chemical solvents. Wine -purpose cork stoppers are generally classified under three categories: natural whole cork stoppers, polymer cork stoppers made cork powders processed with pressure-polymerization moulds, and one-plus-one paster cork stoppers with polymeric material between the two natural cork pieces. Natural cork stoppers usually adopts high-grade raw materials. Polymeric cork stoppers are generally made from high-grade and adequate cork powders pressure-polymerized into material mould with a certain density. Agglomerated cork sticks test report: Tests sample Average Max. Min. Moisture(%) 50 8.4 9.0 8.0 Diameter(mm) 50 25.1 25.6 24.6 Length(mm) 50 630.7 635.0 630.0 Apparent Density(kg/m3) 50 264 283 252