3.4.1 Type I, IB 7 and IC coatings. Type I and IB coatings shall be theresult of treating aluminum and aluminum alloys electrolytically in a bathcontaining chromic acid to produce a uniform anodIc coating on the metalsurface. Type IC coatings shall be the result of treating aluminum andaluminum alloys electrolytically in a bath containing mineral or mixedmineral/organic acids (non-chromic acid) to produce a uniform anodic coatingon the metal surface. Unless others speclfied in the contract , purchaseorder or applicable drawing, Type I coatings shall not be applied to aluminumalloys with a nominal copper content in excess of 5.0 percent; nominal siliconcontents in excess of 7.0 percent; or when the total a]lowable contents ofnominal alloying elements exceed 7.5 percent. Heat treatable alloys which areto receive a Type I, IB, or IC coating shall be in the required temperobtained by heat treatment, such as -T4, -T6, or T73, prior to anodizing.