Throwing power / covering power

Illustrated explanation

A coating must attach, cover the surface and meet thickness requirements

2Throwing power / covering power
A coating must attach, cover the surface and meet thickness requirementsCallout 1 identifies the coating-to-substrate interface and an exaggerated local separation. Callout 2 follows a coating over raised and recessed areas; deposited material can cover both areas yet have unequal thickness. Current term: Throwing power / covering power, callout 2. 1 Attachment at the interface Coating Separation Substrate Adhesion needs its specified assessment Conceptual separation, not a test result 2 Coverage and distribution Exposed face Recess Deposit present ≠ uniform thickness Covering power: deposit presence Throwing power: thickness distribution
  1. Coating adhesion

    Adhesion concerns attachment at the layer-to-substrate interface. Assess it with the specified preparation and test method; thickness and corrosion resistance require their own evidence.

  2. Throwing power / covering powerThis term

    Covering power concerns whether difficult areas receive a deposit. Throwing power concerns the relative thickness distribution; complete coverage can still have a nonuniform coating thickness.

One section locates the interface between a coating and its substrate. Another compares deposit presence and unequal thickness on exposed and recessed surfaces, separating covering power from throwing power.

Conceptual deposited layers with exaggerated thickness and separation. The drawing is not an adhesion test result, a bath-performance prediction or a corrosion rating; actual process and part geometry need assessment.

ReferencesISO 2819:2017 — Electrodeposited and chemically deposited coatings — Adhesion testsISO 2080:2022 — Surface treatment and coatings — VocabularyISO 4527:2003 — Electroless nickel-phosphorus coatingsNickel Plating Handbook — Electroplating fundamentals and coating distribution