Popular anti-rust finishes
- Zinc plating — good protection, great value, many colours; the default for general screws/bolts.
- Phosphate — mid-level protection, matte surface, excellent paint adhesion; popular as a paint primer or with an oil top-coat.
- Black oxide — baseline protection, sharp black look, almost no dimensional change; needs oil to help.
Quick comparison
Overall corrosion: zinc (especially dark chromate) > phosphate > black oxide.
Cost/value: zinc and black oxide are usually economical; phosphate depends on the job.
Looks: glossy/matte black from black oxide and phosphate; zinc offers several colours.
Thread dimensions: black oxide changes them least—best for tight fits.
What we recommend
Outdoor / high corrosion: zinc with yellow/green chromate plus a sealer.
Before painting: phosphate as a primer.
Indoor, sharp black look: black oxide plus oil.
Unsure? Tell us the service conditions and budget and we will compare and propose the best value.
FAQ
Which finish protects best?+
For pure corrosion, zinc with dark chromate plus a sealer lasts best at a good price; very harsh duty has specialty coating systems.
Does black oxide stop rust?+
At a basic level, and it needs oil. It suits indoor/decorative use more than heavy corrosion duty.
Can phosphate be used alone for rust?+
Phosphate gives mid-level protection and is usually paired with oil or paint, so it works best as a primer rather than alone.
Free Engineering Tools
- Hardness Converter HRC ↔ HV ↔ HB
- Which Steel Grades Harden — and How Far
- Fastener Weight: pcs ↔ kg
- Finishing Specification Builder for Purchasing and QC
- Salt Spray Test Plan Builder
- Coating thickness → thread fit (GO/NO-GO)
- Hydrogen Embrittlement — is baking required?
- Bolt Tightening Torque & Proof Load
- Thread Engagement Length
- Bolt Size Estimator (from load)
- Bolt Property Class — Mechanical Properties (ISO 898-1)
Related comparison guides
- Zinc plating vs Dacromet / zinc flakeZinc plating vs Dacromet: which coating for screws and bolts?
- Black oxide vs PhosphateBlack oxide vs phosphate: which finish for screws, nuts and bolts?
- Electroplated zinc vs Hot-dip galvanizingZinc plating vs hot-dip galvanizing: which one does your fastener need?
- Zinc plating vs Zinc-nickelZinc plating vs zinc-nickel: when is the upgrade worth paying for?
- Barrel plating vs Rack platingBarrel plating vs rack plating: how small fasteners are actually plated
- Zinc phosphate vs Manganese phosphateZinc phosphate vs manganese phosphate: match the coating to the job it does
Technical content review
Reviewed by the V.S. Heat Treatment QA and production team—heat-treatment and finishing operations since 1994 under an ISO 9001:2015 quality system.
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