Enamel rating is an industry standard test that is used to check the integrity of coatings or lacquer on cans, ends and other metal packaging. A can is filled with conductive electrolyte (typically 1% saline solution), then a small, safe voltage is applied between the electrolyte and the metal can body. If the inner protective coating (traditionally referred to as "enamel") has been applied perfectly, it will act as a conductivity barrier between the eletrolyte and the metal product. Therefore, any metal exposure caused by microscopic imperfections in the lacquer is determined by measuring the amount of electrical current flowing through the system. Flat products such as ends/lids and samples from coated sheets can be tested with dedicated adapters.