Preventing Corrosion with Protective Paint Coatings

Red lead, the best known corrosion inhibitive pigment and the one with the longest record of successful performance, is used as the sole pigment or in combination with other pigments incorporated in a suitable binding medium or vehicle. It is used to keep the metal surface in a non-corroding or passive state. To reduce painting costs, protective coatings should be carefully applied to a properly prepared surface. Factors to be considered in formulation and proper use of red lead paints are given, and for guidance of the maintenance engineer, a classification of red lead paints according to intended exposure conditions, and a reference listing of current specifications useful as a procurement basis is included. Factors governing performance of paint coatings are listed as: Nature of metal to be coated, surface preparation, intended environmental conditions and paints, primers, topcoats. Illustrations show results after exposure of several surface preparation methods and application schedules. Protective paint systems for principal exposures are recommended, and a guide for selection of the correct red lead paint keyed to environments is given in tabular form.