Hardcoat Blind Holes or Through HolesThrough holes (TH on drawing at right) will hardcoat evenly up to twice the length of the diameter (X).Blind holes (BH on drawing at right) will only hardcoat to a depth equal to the diameter of the hole (X=Y).

MaskingMasking is required where no build up is desired or when a part needs both anodizing & chemical conversion. All threaded holes, 1/4" or smaller, are typically masked when hardcoating unless otherwise specified. Holes with heli-coils must be masked. Any dissimilar metal (steel, brass, bronze) or any form of plating will burn off in the anodizing tank unless masked.http://www.anodizing.org/Reference/reference_guide.html