Abstract: A process for producing a heat-shrinkable polypropylene film, which comprises stretching a film of a polypropylene resin firstly in one direction, then heat-treating it, and further stretching it in a direction perpendicular to the direction of the first stretching.

Abstract: An aluminum or aluminum alloy is electrolyzed in an electrolytic bath composed of an aqueous solution containing at least one of hydroxides and salts of alkali or alkaline earth metal and further optionally including at least one substance capable of forming barrier-type layer selected from the group consisting of inorganic acids, organic acids and ammonium salts of weak acids by applying an alternating current to form a grain-like or wooden like pattern on the surface thereof. The thus obtained grain-like pattern may be directly subjected to usual coloration treatments or may be anodically oxidized prior to the usual coloration treatment.