Performance in Atmospheric Exposure of an Aluminium Alloy Anodised by the Sulphuric Acid Process for Architectural Use: Report prepared on behalf of the former C.I.D.A. Working Panel for Atmospheric Exposure Testing

Abstract

Specimens of aluminium magnesium silicon alloy to the HE 9 designation of BS 1476 were anodised to two anodic film thicknesses and sealed using four different processes; two methods of surface pretreatment of the metal were used prior to anodising. All the HE 9 material was derived from a single source but specimens were processed by each of the participating member countries in sufficient quantity to allow triplicate exposures to be mounted at five exposure sites throughout Europe. The five sites covered a range of atmospheric conditions and the use of triplicate exposure specimens enabled variations to be made in the degree of maintenance applied to individual replicate groups at each site.Exposure of the specimens began in the Spring of 1965, and they have shown little deterioration during the six years exposure period covered by this report. The present paper illustrates the excellent performance obtained and comments on the small effect on performance which has so far resulted from the variations in processing included in the test programme.