Every Finish Option for Metal Parts

This is the comprehensive list — every common metal finishing process, what it does, what materials it works on, and when to specify it.

Mechanical Finishing

Bead Blasting

Glass or ceramic beads propelled at the surface create a uniform matte texture. Hides tool marks, provides consistent appearance. Spec: typically medium (~100 grit) for general use.

• Materials: All metals
• Result: Matte, non-directional texture
• Cost: $

Tumbling / Vibratory Finishing

Parts placed in a tumbler with abrasive media. Deburrs edges, blends surfaces, and can produce a polished finish over time. Great for batch processing small parts.

• Materials: All metals, some plastics
• Result: Rounded edges, smooth surfaces
• Cost: $ (batch process)

Brushing

Abrasive brush or belt creates directional lines. The “brushed metal” look on consumer electronics, appliances, and architectural panels.

• Materials: Stainless, aluminum
• Result: Linear grain pattern
• Cost: $

Polishing / Buffing

Progressive abrasives from coarse to fine, finishing with compound on a buffing wheel. Mirror finish requires multiple stages and significant labor.

• Materials: All metals
• Result: Mirror (#8) down to satin (#4)
• Cost: $$–$$$ (labor intensive)

Chemical / Electrochemical Finishing

Zinc Plating

Electrodeposited zinc layer (0.2–1.0 mil). Protects steel from corrosion via sacrificial protection — zinc corrodes first. Clear, yellow, black, or olive drab chromate conversion coating added after plating.

• Materials: Steel
• Spec: ASTM B633, Class Fe/Zn 8 (8 microns) typical
• Cost: $

Nickel Plating

Hard, bright, corrosion-resistant. Electroless nickel (EN) provides uniform thickness even in recesses — critical for precision parts.

• Materials: Steel, aluminum, copper alloys
• Spec: AMS 2404 (electroless), ASTM B689 (electrolytic)
• Cost: $$

Chrome Plating

Two types: decorative (thin, over nickel) and hard chrome (thick, for wear resistance). Hard chrome: 1–20 mil, 68-72 HRC surface hardness.

• Materials: Steel primarily
• Hard chrome uses: Hydraulic cylinders, mold surfaces, bearing journals
• Cost: $$$

Anodizing (Type II and III)

Converts aluminum surface to aluminum oxide. Type II: 0.2–1.0 mil, decorative, dyeable. Type III (hardcoat): 2–4 mil, extremely hard and wear-resistant.

• Materials: Aluminum, titanium
• Spec: MIL-A-8625
• Cost: $$ (Type II), $$$ (Type III)

Passivation

Nitric or citric acid treatment that removes free iron and restores chromium oxide layer on stainless steel. Not a coating — it’s a cleaning process.

• Materials: Stainless steel
• Spec: ASTM A967, AMS 2700
• Cost: $

Black Oxide

Chemical conversion of steel surface to magnetite (Fe₃O₄). Provides mild corrosion resistance (with oil), attractive black appearance, and zero dimensional change.

• Materials: Steel, stainless, copper
• Cost: $

Phosphate Coating

Zinc or manganese phosphate. Provides corrosion protection, oil retention (for moving parts), and paint adhesion. Common as a pre-paint treatment.

• Materials: Steel
• Cost: $

Applied Coatings

Powder Coating

Electrostatically applied dry powder, cured in an oven. 2–6 mils. Extremely durable, hundreds of colors.

• Materials: Steel, aluminum (conductive metals)
• Cost: $

Wet Paint (Spray)

Liquid primer + color + clear coat. Any color, any material. Less durable than powder but more versatile.

• Materials: Anything
• Cost: $$

Cerakote

Thin-film ceramic polymer coating. 0.5–1.0 mil. Exceptional durability, chemical resistance, and heat resistance (up to 1800°F for some formulations).

• Materials: Metals, plastics, wood
• Use: Firearms, automotive, aerospace, tactical
• Cost: $$$

Need finishing on your parts? Tell us your requirements — material, environment, appearance, and budget.