Edco Copper Foil is a high quality copper foil. Edco foil has the strongest adhesive in the industry and longest shelf life. Edco Copper foil uses a "dead soft Copper" that adheres closely to your glass. This saves you time and makes your finished work stronger and more attractive. Edco copper fiol is specially formulated to withstand every chemical normally used in stained glass work, so you will always be pleased with the final results. Edco copper foil lasts and lasts, so you dont have to use it all right away, even a year later, its as good as the day you opened the package.