Black or darker base coat for Zinc and Black Chromate plating

A. The problem occurs due to :

1) Insufficient bonding between the passivate and plated zinc.
2) Insufficient time allowed for the passivated film to cure , which is not hard enough to take a threading operation.

Bond between Plate and passivate can improve with selection of the right Zinc Plating Process which does not co deposit organics which inhibit bonding , and, use of suitable activators in line to activate such deposits . Good housekeeping is the eventual answer, Correct process selection is the long term answer. The Question does not state which process is used: Acid , cyanide or alkaline zinc ?

It is Alkaline Non Cyanide Zinc that bonds best with Black silver based chromate.
2) Cure: The chromate film needs 24 to 48 hours to cure fully.
3) Topcoat: A water soluble Acrylic based topcoat over the black passivate will improve chip resistance when used correctly.

What I am saying is chipping of the film is indicative of poor plating post treat practice. The problem is solvable without changing the base to a darker metal.

A. Black chrome as featured in the AnoBlack Cr data sheet at our website and widely available from other shops has been used for the heads of fasteners used to hold avionic controls in aircraft cockpits. The more abrasion resistant black withstands rigors of repeated assembly and adjustment. Alternatively, you may try a salt bath nitriding process such as QPQ from Kolene. It achieves a black nitride surface that is superior to any plated coating.