A study of the weathering resistance of vitreous enameled architectural panels \Was begun by the National Bureau of Standards in 1939. The study involves t,64 one-foot-square panels, representing 14 types of enamel and a like number ~f 4-by 6-in. laboratory specimens. At the end of the first year of exposure at 1C0ur locations selected for different climatic conditions, over half of the panels ~howed no visible weathering effect, and in no case did weathering produce any ~ailure of the enamel to protect the underlying metal from rusting.The full-mat enamels were found unsuited for architectural use where appearance is important, because of fading and of difficulty in cleaning. Mild fading, found on some of the non-acid-resistant colored enamels, was associated with a minute pitting of the enamel surface, probably caused by the presence of acidforming gases in the atmosphere. The enamels of high acid resistance did not s how this effect.

A study of the weather resistance of porcelain-enamel ed architect ural panels was begun at the National Bureau of Standards in 1939. The s tudy in vol yes 864 I-foo t-square panels and a like num ber of 4-b y 6-illch laboratory specimens. A previou s report (H)42) gave t he res ults after 1 year of expos ure. The prese nt paper describes t he condition of the panels after 7 years of weathering at Washin gton, D . C., St. Louis, Mo. , Lakeland, Fla., a nd Atlantic City, N. J.The res ults of t he 7-year inspection showed a good correlation between the ac id resistance of enam els and their resistance to weatherin g. \Vh ere ini t ial coverage was complete and no m echani cal damage had occulTed, protection of th e m e tal by the ell a rn el for all specim ens \\:1S unimpaired aft e r 7 years.Fading of colored en amels occ urred only on t hose pa nels with \'er y poo r acid res i~ta'lce .

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A new type of ceramic coating for the protection of low-carbon steel in high-temperat ure service was d eveloped during the war at the National Bureau of Standards and was used by the Army and Navy on the exhau st system s of certain a ircraft and other vehicles. The outstanding features of these coatings are (a) high resistance to chipping unde r repeated thermal hock, (b) protection of the metal against ox idation during prolonged expo. ure at temperat ures up to about 1,250° F , (c) freedom from the crac kin g and blistering produced in conventional porcelain enamels under comparable conditions of high temperature and severe Lhermal gradients, and (d) a mat surface wh ich does not show high lights and , t herefore, decreases t he visibility .