Adhesion of Photopolymer Coatings and Printed Features to Metals: Oxide State, Surface Preparation, Cure Stress and Durability

Adhesion of a photocurable coating or printed feature to a metal is not a property of the resin alone. It is the response of a declared alloy, its near-surface oxide, hydroxide and contamination state, the applied liquid, the evolving cured network, the specimen geometry and the conditioning history. A contact angle, cross-hatch class or pull-off strength can be useful, but none identifies the controlling interface or establishes durability by itself. This review defines a metal-specific qualification architecture. It begins with alloy and surface-state identity, verifies what cleaning, abrasion, activation, conversion or priming changed, and separates wetting, interfacial chemistry, cure conversion, residual stress and mechanical failure. It then requires locus-resolved adhesion testing before and after controlled humidity, immersion, thermal, corrosion or deformation histories. The evidence supports paired chemical and mechanical measurements and shows why aluminium, copper, steel and zinc-coated substrates cannot be placed on a universal adhesion scale. It does not establish a commercial preparation recipe, universal roughness or surface-energy target, transferable cure-stress limit, adhesion threshold, ageing acceleration factor or service-life claim.