During the manufacturing process of aluminum cans, the last step in creating the can takes the opening at the top and rolls it back onto itself, forming a curl. This is what the aerosol valve gasket is eventually sealed on to. The gasket needs a smooth, accurate surface to create a proper seal and prevent gasses and product from leaking. But sometimes, stretch marks or “eye lashing” are left on the curl. With conventional aerosols that use hydrocarbons, the rubber material of the gasket will sometimes swell once it comes in contact with the solution, helping to form a tight seal. But with BOV or chemicals propelled by compressed air, there is no reaction with the rubber, so it is essential to remove these imperfections before attaching the gasket.