Composite-coated flat-rolled sheet metal manufacture

Process for preparing and protecting flat-rolled sheet metal for fabricating pre-coated sheet metal can parts ready for direct use as fabricated for canning comestibles, comprising the steps of

• providing flat-rolled sheet metal selected from the group consisting of flat-rolled steel in the range of about 50 to about 110 pounds per base box and flat-rolled aluminum having a thickness range of about 0.005 inches to about 0.015 inches;
• presenting opposed planar surfaces subject to surface oxidation;
• cold-rolling the sheet metal with roughened rolls to provide a surface texture on each of its planar surfaces which contributes to mechanical interlocking of the subsequently applied coating;
• delivering the cold-rolled textured-surface sheet metal for removal of surface oxidation;
• carrying out removal of oxidation from both textured sheet metal surfaces to present a substrate for application of organic polymeric coating to provide can stock;
• then
• directing the substrate into an E-coat aqueous bath in a manner to avoid oxidation of its textured surfaces,
• selectively applying an organic coating from the aqueous bath solely by electrolytic means so as to stabilize each surface against oxidation while retaining at least a portion of said texture on each said E-coated surface,
• said electrolytic coating from the E-coat aqueous bath being carried out with the sheet metal substrate as the cathode;
• drying said coated surfaces as directed from the E-coat aqueous bath so as to remove moisture and at least partially cure said E-coat organic coating;
• and
• non-electrically applying a smooth-finish outer-surface protective organic coating to produce at least one composite-coated surface on which total organic coating is in the range of above about three mg/in.sup.2 to about twenty-one mg/in.sup.2 of said composite-coated surface and, then
• treating the coated substrate for purposes of curing said organic coatings;
• wherein a lubricant is added to the can stock by incorporating a blooming-compound draw lubricant into the outer-surface organic coating, applying a surface-applied draw lubricant onto the outer surface coating, or a combination thereof;
• and
• wherein the composite-coated sheet metal is free of metal or metal compound coatings.