Alternative finishes and coatings

Key takeaways

You can specify custom finishes or coatings for carbon steel and stainless steel bigHead fasteners.
Choose coatings for corrosion resistance, surface cleanliness, friction control, or visual appearance.
Coatings affect surface properties only (corrosion resistance, friction, appearance), not mechanical strength.
Coatings can alter torque behaviour, surface friction, and adhesive‑bonding interaction.
Applicability depends on product geometry and coating‑process constraints.
Minimum order quantity: 500 pieces per product type (mixed types cannot be combined).

Customisation scope for alternative finishes and coatings

You can request alternative finishes or coatings for any standard carbon steel or stainless steel bigHead fastener, subject to:

Suitability of the fixing form (e.g. features that can trap residue or other geometric limitations within bulk-coating processes).
Coating‑process capability (e.g. surface coverage issues or witness marks from bulk tumbling or racking).
Minimum order quantity of 500 pieces per product type.

Carbon steel

For carbon steel, the standard zinc‑plated finish can be replaced with higher‑performance corrosion‑resistant systems such as ZinKlad 1000, zinc-nickel plating, or zinc‑flake coatings.

These finishes, listed according to their bigHead reference number, significantly increase corrosion protection or provide specific surface properties:

SC001 → ZinKlad 1000 TnT 12 Clear (Ford S450B)
SC002 → ZinKlad 1000 TnT 15 Black (Ford S450)
SC041 → Zinc Nickel with Clear Trivalent Passivate (DBL9440.49)
SC043 → Zinc Flake Plus VL Sealer (DBL9440.40)

Stainless steel

For stainless steel, optional treatments include nitric passivation or a dry‑film coating such as black Xylan, offering cleaner surfaces, reduced friction, or a consistent aesthetic:

SC036 → Nitric passivate to BS EN ISO 2516:1997 – Method C2
SC047 → Xylan 5230 Black

We can help you choose the optimal coating for your application – get in touch.

What's outside the scope of finish/coating customisation

Complex requests are handled through our Create service. If you’d like to combine multiple customisations – such as coatings plus non-standard thread forms – we can work with you to create a solution.

Design and performance considerations for finishes and coatings

Design impact

Finishes and coatings do not change the overall form and geometry envelope of the bigHead fastener. However, they can influence:

Surface thickness variation from coatings that add measurable layers.
Thread behaviour, especially where coating thickness or low‑friction layers affect torque input.
Adhesive bonding interactions, as coating chemistry may alter surface energy.
Appearance requirements, particularly when specifying uniform black or matte coatings.

Performance impact

The main performance changes relate to corrosion resistance and surface behaviour.

Corrosion resistance

Enhanced coatings provide substantially higher protection than standard zinc plating, with some systems achieving extended salt‑spray performance (e.g. 720–1,000 hours to red rust).

Surface friction and wear

Coatings for carbon steel fasteners with specific torque and tension (TnT) control ensure consistent thread friction for torque-controlled assemblies. Xylan coatings produce a low‑friction surface that can alleviate thread galling issues with stainless-steel fasteners.

Surface cleanliness and passivity

Stainless steel passivation treatments can restore or improve the oxide layer of the bigHead product after manufacturing, enhancing corrosion resistance in demanding environments.

Finishes and coatings do not increase the mechanical strength of the fastener itself. Performance benefits are at the surface level only. For more details, get in touch.

Specification examples for finish/coating customisation

Example 1: Enhanced corrosion resistance (carbon steel)

To specify a carbon steel M1/B20 product with M6 × 20 threaded stud and ZinKlad 1000 (clear) finish:

Product type: M1/B20
Thread × nominal length: M6 × 20
Customisation suffix: SC001

→ M1/B20 M6 × 20 SC001

Friction coefficient: 0.12 (TnT 12)
Meets the requirements of: Ford S450B
1,000 hrs to red-rust (ISO flat plate test)

Example 2: Aesthetic appearance (stainless steel)

To specify a 316 stainless steel sighted SF2/S38A product with M8 × 15 collar and Xylan 5230 Black coating:

Material prefix: S (316 stainless steel)
Product type: F2/S38A
Thread × nominal length: M8 × 15
Customisation suffix: SC047

→ SF2/S38A M8 × 15 SC047

Coating appearance: black, semi-matte

Example 3: Out of scope

A request for 100 pieces of bigHead M1/ B15 M5 × 20 SC043 and 250 pieces of bigHead F2/ S23 M6 × 20 SC043 (DBL9440.40 customisation option) would not meet our minimum order quantity of 500 pieces per product type.

FAQs

Do alternative finishes or coatings change the strength of the fastener?

No. Alternative finishes and coatings only modify surface‑level properties such as friction, corrosion resistance, or appearance. They do not increase the mechanical strength of the fastener.
Can I combine different product types to reach the 500‑piece minimum order?

No. The 500‑piece minimum applies per product type. Mixed configurations cannot be combined to meet the threshold.
Are all bigHead products compatible with every coating option?

Compatibility depends on the geometry of the fixing and the coating‑process limitations (e.g. residue traps, tumbling witness marks). Get in touch with us for advice on compatibility.
Will coatings affect thread performance or torque settings?

Potentially, yes. Coatings such as TnT systems or Xylan influence friction levels, so torque values or assembly behaviour may differ from standard finishes. We can advise where torque‑controlled assembly is important.
When should I choose a stainless steel passivation or a Xylan coating?

Choose passivation when you need improved surface cleanliness or corrosion resistance of 316 stainless steel.

Choose Xylan when you need a low‑friction, anti‑galling surface or a consistent black aesthetic.