Fundamentals of Corrosion Protection by Organic Coatings

An overview of the principal factors involved in the initiation and propagation of the corrosion of painted steel is presented. One of the major protective functions of the paint system is to act as a barrier to electrolyte; corrosion begins at sites where penetration of electrolyte has occurred. Loss of paint adhesion, caused in most cases by cathodically produced alkali, results in the spread of corrosion. Improved corrosion protection can be obtained by use of alkali-resistant paint binder resins. Corrosion inhibitive pigments can improve performance by slowing the overall corrosion rate; conversion coatings can slow the lateral spread of alkali attack.