Black Oxide (Blued)
Black oxide (blued) finish: 8-24 h protection once oiled, for dry indoor service where no coating build-up is acceptable.
| Finish Code | TZ007 |
|---|---|
| Environmental Grade | Conventional alkaline oxidising; parts must be oil-dipped before use |
| Salt Spray Standard | 8-24 h after oil dipping; dry indoor service only |
| Appearance / Colour | Black / blue-black |
| Suitable For | All types of screws, steel fasteners and machined parts |
| Features | No dimensional change; requires oil film |
| Environmental Compliance | REACH and RoHS compliant |
Overview
Surface finishing on a fastener is a functional coating, not a cosmetic one: it sets the friction coefficient that determines how much of the applied torque becomes clamp load, and it defines how long the part survives in a corrosive environment. Two finishes that look identical can differ by a factor of several in salt-spray hours and by enough in friction to change the torque specification. This listing: finish code TZ007, salt spray 8-24 h after oil dipping, appearance / colour Black / blue-black, environmental compliance REACH and RoHS compliant.
Advantages
Barrier coatings protect the base metal, while sacrificial coatings protect the steel even at a scratch; the choice depends on whether the joint will be damaged in service.
Hydrogen embrittlement risk separates processes: electroplating on high-strength steel needs a de-embrittlement bake, while mechanical and flake coatings avoid the risk entirely.
Friction coefficient changes with coating: a zinc-flake coating typically runs lower and more consistently than electroplated zinc, which is why torque tables are finish-specific.
Applications
Automotive underhood and body joints, outdoor equipment, marine and coastal installations, electronics hardware, and any joint where the torque specification is tied to a friction value.
Quote the standard, the hours and the acceptance criterion together — a salt-spray figure without the test method is not a specification. Check that the coating process is compatible with the core hardness of the part.
Product information is supplied by Toprecision. Custom parts can be produced to drawing — contact us for samples or a quotation.
FAQ
What does this finish provide?
Finish Code TZ007, Environmental Grade Conventional alkaline oxidising, Salt Spray Standard 8-24 h after oil dipping, Appearance / Colour Black / blue-black.
How does it affect torque and friction?
Carbon Steel.
What should I verify before ordering or installing it?
Quote the standard, the hours and the acceptance criterion together — a salt-spray figure without the test method is not a specification. Check that the coating process is compatible with the core hardness of the part.