Before comparing finishes, answer these—they decide most of the choice for you:
| Finish | What it does | Best for | Relative cost |
|---|---|---|---|
| As-cast / deburr | Raw cast surface, edges broken | Hidden, non-critical parts | Lowest |
| Shot blasting | Uniform matte texture; cleans & preps surface | Pre-treatment before coating; even cosmetic matte | Low |
| Chromate conversion (chem film) | Thin corrosion-resistant conversion layer; paint base; conductive | Functional corrosion protection, electrical grounding | Low |
| Anodizing (Type II / III) | Hard, integral oxide; wear & corrosion resistant; colorable | Durable cosmetic + wear surfaces | Medium ($0.10–0.30/cm²) |
| Powder coating | Thick, tough, UV-stable colored film | Outdoor & automotive, bold color | Medium ($0.12–0.35/cm²) |
| E-coating | Electro-deposited, 100% uniform thin film into cavities | Complex parts needing complete corrosion defense | Medium–High |
| Polishing | Bright, smooth decorative surface | High-end cosmetic parts | High (labor) |
A quick note on castings specifically: high-silicon casting alloys (like A360/A380) anodize to a duller, grayer finish than wrought aluminum because the silicon does not anodize. If a bright decorative anodize is essential, that drives alloy and finish choice—see our material comparison guide.
The two most-asked-about finishes, side by side:
| Factor | Anodizing | Powder Coating |
|---|---|---|
| Layer | Integral oxide (grows into metal) | Applied film on top |
| Dimensional buildup | Minimal (tight tolerances) | Thicker film |
| Wear resistance | Excellent (esp. Type III hardcoat) | Good |
| Color range | Limited, metallic look | Wide, any RAL color |
| UV / outdoor | Good | Excellent |
| On cast alloys | Duller (silicon effect) | Hides surface, consistent color |
Pick anodizing for tight tolerances, wear surfaces, and a metallic look. Pick powder coating for bold color, heavy outdoor/UV duty, and to mask a cast surface.
Traditional hexavalent chromium chromate coatings are being phased out under RoHS and REACH. For new designs, specify RoHS-compliant trivalent chromate (Cr3+) or alternative conversion coatings. If your part ships into the EU or to RoHS-bound customers, confirm the finish chemistry up front to avoid a costly re-spec later.
There is no single best finish—it depends on environment, function, and budget. Powder coating suits outdoor colored parts, anodizing suits wear surfaces and tight tolerances, e-coating suits complex parts needing full corrosion defense, and chromate conversion is a low-cost functional option.
Yes, but high-silicon casting alloys anodize to a duller, grayer finish than wrought aluminum because silicon does not anodize. For a bright decorative anodize, alloy choice and surface prep matter.
Anodizing gives a thin, integral, wear-resistant layer with minimal dimensional buildup and a metallic look. Powder coating gives a thicker, tough, UV-stable film in any color. Choose by whether you need tolerance and wear (anodize) or color and outdoor durability (powder).
Shot blasting cleans the surface and creates a uniform texture that improves coating adhesion and durability, so it is commonly used as a pre-treatment before powder coating, painting, or anodizing.
Hexavalent chromium chromate is being phased out under RoHS and REACH. RoHS-compliant trivalent (Cr3+) chromate and other conversion coatings are the current alternatives.
Tell us your part's environment, function, and budget—Matson Alucasting will recommend the right finish and apply it in-house, from shot blasting to anodizing, powder coating, and e-coating.