01
Hot-dip galvanized
Matte silver grey
Immersion in molten zinc
Surface protection and performance
Metal coatings
for bolts and fasteners
Processes backed by quality certificates and technical criteria for thickness, adhesion, coverage, corrosion resistance and inspection.
Corrosion protection
Technical alternatives
5 coating families
Documented quality
Traceability for every process.
Coatings applied to bolts, fasteners and metal components come with quality certificates issued in accordance with the applicable technical standards and validated by qualified technical staff.
Visual guide
Five coatings, five different behaviours.
Appearance helps identify the system, but the final selection must answer to the real service conditions.
02
Zinc plated
Bright silver
Zinc electroplating
03
Yellow chromate
Iridescent gold
Zinc with chromate passivation
04
Zinc flake
Grey with a lamellar texture
Heat-cured zinc flakes
05
Xylan / PTFE
Available in several colours
High-performance fluoropolymer
Coating comparison
Colour, protection and performance for each application.
Colour makes it easy to tell coating alternatives apart; the technical selection always depends on the real service condition.
Standards and processes
Protection is specified, not improvised.
01
ASTM B633-23
Zinc electroplating and chromate passivation
Thin zinc coating with a smooth, bright finish. Passivation produces the characteristic iridescent yellow chromate appearance.
- Light silver or blue-tinted coating
- Iridescent yellow chromate
- Thin, uniform film
Indicative application
Indoor use and applications where a clean appearance and thickness control matter most; it offers less resistance to prolonged outdoor exposure.
02
ASTM F1941-25
Zinc and zinc-alloy coatings for fasteners
Sets out requirements for electrodeposited coatings applied specifically to steel bolts, nuts and other fasteners.
- Thickness and adhesion
- Coverage and corrosion resistance
- Post-treatments and inspection
Indicative application
Industrial fasteners whose coating must be documented against defined process, performance and inspection criteria.
03
ASTM A153-23 · ASTM F2329-23
Hot-dip galvanizing
Immersion in molten zinc followed by centrifuging to remove the excess, giving a thick, uniform layer with high corrosion resistance.
- ASTM A153: hardware and non-threaded items
- ASTM F2329: primarily threaded items
- Matte grey, opaque and thicker coating
Indicative application
Standard industrial protection for outdoor use and environments with significant corrosion exposure.
04
ASTM F3393-24
Zinc flake coatings
Non-electrolytic system of zinc flakes, with or without aluminium, oven-cured to produce a uniform, highly adherent film.
- Classification, thickness and adhesion
- Controlled coefficient of friction
- Corrosion, performance and inspection
Indicative application
High-strength fasteners and joints with controlled torque–tension requirements.
05
Heat-cured process
PTFE-based fluoropolymer · Xylan
Combines high-performance resins with dry-film lubricants to protect against corrosion, chemical attack, wear and abrasion.
- Low coefficient of friction
- Moisture repellency
- Electrical insulation
- Chemical, thermal and abrasion resistance
Indicative application
Applications requiring controlled friction, non-stick behaviour, anti-galling performance and durability in demanding environments.
Selection criteria
The ideal coating depends on the service conditions.
Assessing these factors makes it possible to define effective corrosion protection for the service life of the component.
- 1
Exposure environment and corrosivity category to ISO 12944.
- 2
Operating temperature and contact with chemical agents.
- 3
Material and property class of the bolt or fastener.
- 4
Applicable technical standards and expected service life of the component.
ASTM F3393-24
Advantages of heat-cured coatings.
The non-electrolytic process is particularly relevant for high-strength fasteners and complex geometries.
- 01
Resistance of up to 5,000 hours in salt spray testing, per a specification based on ISO 12944.
- 02
Free from hydrogen embrittlement, since no electrolytic process is involved.
- 03
Uniform film on complex geometries and threads, without excessive build-up.
- 04
Controlled coefficient of friction for torque–tension requirements.
- 05
A range of colours through final layers or topcoats.
- 06
High chemical and temperature resistance, depending on the system applied.
- 07
Modern formulations free of hexavalent chromium and low in volatile organic compounds.
Critical decisions
The coating is part of the safety and performance of the bolt.
This should not be treated as an optional decision: the environment, the strength of the fastener and the standard all shape the outcome.
Service life against corrosion
The question is not only which coating looks better, but how long the bolt must last before corrosion appears in its real environment.
Total cost of the decision
Choosing correctly from the start can reduce replacements, maintenance, downtime and the risk of incompatibility during installation.
Hydrogen embrittlement
A critical risk in high-strength fasteners when processes do not comply with the applicable standards and technical controls.
Coating selection
What level of protection does your fastener really need?
Share the material, property class, environment, temperature and expected service life. Our technical team will review the right alternative.