The laboratory evaluation of paint as a protective coating is usually made with test panels of a single metal, such as iron. However, paint systems are frequently used on structures which may consist of a combination of metals, such as iron and copper, brass or bronze. It is well known that, when two different metals are connected in the same structure in an aqueous environment, one of the metals corrodes at a higher rate and the other at a lower rate than either would corrode normally, if they were not coupled. This is galvanic corrosion.
The degree of acceleration or deceleration of corrosion depends upon several factors, one of which is the relative position of the two metals in the familiar electrochemical series. Steel and copper or copper alloys are common metals which are often used together in diverse structures. When these structures are exposed in aqueous environments, such as...
