The simplest, and longest-established, method of estimating corrosion is weight loss analysis. A weighed sample (coupon) of the metal or alloy being tested is introduced into a corrosive enviroment and later removed after a certain amount of time has elapsed. The coupon is then removed with as little disturbance as possible cleaned and reweighed. The weight loss is converted to a total thickness loss, or average corrosion rate.
Weight loss measurement is still the most widely used means of determining corrosion loss.