ASTM B537-70 pdf free.Standard Practice for Rating of Electroplated Panels Subjected to Atmospheric Exposure.
There are many modes of deterioration in appearancementioned in 4.2 but this list is not exhaustive, and as newplating systems are developed and introduced to industry, theymay well exhibit new types and modes of deterioration.Unlike the protection rating, the appearance rating isbased not only on the area of the defects but also on theirseverity: the degree to which they would detract from thecommercial acceptability of an article of appearance similar tothat of the panel.The appearance rating is based, in the first instance,onthe protection rating. Since corrosion of the substrate alsodetracts from appearance,the appearance rating can be nohigher than the protection rating. If basis metal corrosion is the only defect, there beingno additonal defects affecting only the coating, the appearancerating is the same as the protection rating.If there are surfacedefects not accounted for in the protection rating, the appear-ance rating will be one or more units lower than the protectionrating.This lowering of the appearance rating is referred to inwhat follows as the “penalty.”The inspector must decide, on the basis of best currentpractice and opinion，whether a surface coating defect is (1)very slightly,(2) slightly (3) moderately,or (4) severelydamaging to the acceptability of the appearance.Guidelines aregiven below, but judgment factors inevitably enter into thedecision. Defects only slightly damaging may include very lightsurface pitting that detracts little from the reflectivity，lighttarnish or stain easily removed by mild cleaning (such as wouldbe given, for instance, in normal car-washing practice), super-ficial crack patterns typical of some kinds of chromium plate,and so forth. Such defects, to be categorized as“ slight,”mustnot render the finish commercially unacceptable. Defects moderately damaging include the same typesas in 7.3.1 but more severe， so as to render the appearancequestionably acceptable from a commercial standpoint. Forexample，surface pits that begin to detract from reflectivity;tarnish or stain that, although removable, requires more drastictreatment than routine washing.ASTM B537 pdf download.