Functional purpose
State whether the finish controls corrosion, wear, friction, conductivity, appearance, cleanability or another measurable function.
Manufacturing finishes
Specify the surface as an engineered system—not a colour at the end.
A defensible finish decision connects functional purpose, substrate, pretreatment, masking, build, acceptance method and rework authority.
Control sequence
Six decisions turn a finish name into an inspectable requirement.
Use the sequence during design review and RFQ preparation. Unknown inputs are questions to close—not neutral assumptions.
Substrate and state
Identify the base material, heat treatment and incoming surface condition; the same finish can behave differently on another substrate.
Pretreatment
Cleaning, conversion, activation, blasting or polishing steps need an agreed process basis where they affect adhesion or appearance.
Build and masking
Define thickness or build where relevant, plus threads, fits, contact faces, sealing zones and other areas that must be protected.
Acceptance method
Tie colour, texture, thickness, adhesion, corrosion or visual acceptance to a named method and controlled viewing conditions.
Rework authority
State whether stripping, touch-up, local repair or recoating is allowed and which characteristics must be reverified afterwards.
Decision matrix
Compare finish families through substrate, function and verification.
These rows guide clarification. They are not a universal compatibility table or a statement of supplier capability.
| Finish family | Typical substrate | Decision basis | Evidence to define |
|---|---|---|---|
| Anodising | Aluminium | Oxide type, colour, thickness/class, sealing, contact areas and dimensional allowance. | Process/specification record, thickness or class evidence where required, controlled appearance review. |
| Passivation | Stainless steel | Alloy, prior fabrication/cleaning state, selected chemistry/specification and contamination risk. | Named process route, batch record and any specified verification or cleanliness result. |
| Powder coating | Metals | Pretreatment, powder system, colour/gloss/texture, cure, masking and film-build effects. | Approved colour/texture basis, batch/process record, thickness/adhesion checks when required. |
| Plating | Metals | Deposit system, undercoat, thickness distribution, hydrogen-embrittlement risk, contacts and fits. | Specification, thickness evidence, bake or process record when applicable, lot traceability. |
| Blasting / brushing / polishing | Metal surfaces | Directional grain, abrasive/media, roughness, edge treatment, contamination and cosmetic zones. | Approved comparator or measurable roughness, controlled lighting/distance and handling controls. |
| As-machined / conversion only | Process dependent | Allowed tool marks, burr/edge state, cleaning, preservation and any local functional surface requirement. | Drawing-defined roughness or visual comparator, deburr record and final inspection evidence. |
Claim boundary
Selection guidance is not release authority.
This guide does not certify a material, finish, supplier or part. The controlled drawing/specification, validated process route and authorised technical decision remain decisive.
Source notes
External engineering context used for this guide.
01Protolabs — Anodizing vs. Powder Coating02NIST SP 960-9 — Surface Engineering Measurement Standards
Sources provide general context. Customer specifications, standards and verified project evidence govern each release.
Apply it to a live requirement