JULY, 1936
INDUSTRIAL AND ENGINEERING CHEMISTRY
2. Practically negligible protection is reached with many paints long before the integrity of the coating is seriously impaired, especially on those woods, like white pine and redwood, that hold paints well. 3. Deep chalking, deep checking, and cracking of coatings lead to loss of protection in advance of failure in integrity. Coatings in which chalking and checking penetrate slowly, or in which checking and cracking are long delayed, retain approximately their initial protection until very serious flaking or scaling has developed. The initial protection by coatings, however, varies widely with different kinds of paint and cannot be determined by visual examination. 4. I n the common uses of house paints on wood, protection is of minor importance. For special uses in which maintenance of protection may be important, good aluminum priming paints followed by ordinary paints are especially useful because disintegration of the top coats can be made to reveal the need for repainting a t a time when the protection is still satisfactory and the surface is still in good condition for repainting.
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Literature Cited (1) Browne, E". L., Am. Paint Varnish Mfrs'. Assoc., Sci. Sect' Circ. 290. 202 (1926): Fed. Paint Varnish Production Clubs' OficiG-D
