An exposure test of porcelain enamels on aluminum was initiated by the National Bureau of Standards and the Porcelain Enamel Institute in 1964.The enamels were returned from the exposure sites to the laboratory at NBS to be measured for changes in gloss and col * or after exposures of six months, one year, and three years.Changes were found to be greatest at Kure Beach and least at Montreal and Los Angeles, with moderate changes occurring at Washington and New York.Although the boiling citric acid test is used as an acceptance test for these enamels, the correlation with color change, particularly at Kure Beach, was not as good as expected.A cupric chloride test was developed which shows an improvement in this correlation.(Author).