Finishes

Fastener Finishes & Coatings: The Complete Guide

Professional Fastener Finishing Services for Nuts, Bolts, Washers & Bespoke Components

_Note that not all of these finishes are available to Trojan Special Fasteners and a number of unmentioned ones are. So, if in doubt, please always ask us and we'll find out if our subcontractors can finish your ordered fasteners in the way you need and want.

Choosing the right finish for your fasteners is just as critical as selecting the correct material, thread form, or dimensional tolerance. The coating or finish applied to a nut, bolt, washer, or bespoke component directly determines its resistance to corrosion, assembly performance, operational durability, torque characteristics, and final appearance. At Trojan Special Fasteners, we supply precision-manufactured fasteners across our complete size range – M3 to M52 in metric, 2BA to 2" in Imperial (BSW/BSF), and #8 to 2.1/4" in Unified (UNF/UNC) – with a comprehensive selection of high-performance finishes tailored to your exact specification.

Whether you require standard electroplated coatings for general engineering, heavy-duty hot-dip galvanising for outdoor infrastructure, or specialist zinc flake systems for automotive and aerospace applications, we work with trusted subcontractors to deliver finishes that meet international standards and exceed your technical requirements. All finishes are available in both left-hand and right-hand thread configurations, with selected coatings suitable for oversize thread applications.

Our Core Finishing Processes

  • Galvanising - For ultimate durability in harsh outdoor and marine environments, discover our hot-dip galvanising process. Ideal for structural fasteners, infrastructure projects, and applications requiring long-term corrosion protection to ISO 10684 and BS EN ISO 1461.
  • Phosphating - Explore our wear-resistant manganese phosphate (Parkerising) and paint-base zinc phosphate coatings on our phosphating page. Excellent for high-friction applications, pre-paint treatment, and oil retention in automotive, military, and industrial assemblies.
  • Zinc Flake Coating - Learn about high-performance, non-electrolytic coatings like GEOMET®, Magni, and Dacromet® on our zinc flake coating page. These coatings eliminate the risk of hydrogen embrittlement, making them suitable for high-tensile fasteners (Grade 10.9, 12.9) and critical aerospace applications to ISO 10683
  • Delta Protekt & Delta Tone – Zinc flake alternatives offering thin, uniform coatings with excellent corrosion resistance and no hydrogen embrittlement risk.
  • Zinc Plating - Discover this versatile and cost-effective electroplated finish on our [zinc plating pagehttps://www.trojansf.co.uk/zinc-plating]. Provides excellent corrosion resistance with bright, yellow, black, or clear chromate passivations to ISO 4042, ASTM B633, and BS 7371.
  • Black Oxide (Blackening) – An economical conversion coating providing mild corrosion protection and an attractive matte black finish. Reduces light reflection and is ideal for military, firearms, tools, and decorative applications.
  • Nickel Plating – Bright nickel, electroless nickel, and nickel-phosphorus coatings provide excellent corrosion and wear resistance. Suitable for electrical, marine, and high-temperature applications.
  • Tin Plating – Offers superior solderability and non-toxic corrosion protection, making it ideal for food processing equipment, electrical assemblies, and marine fasteners to ASTM B545.
  • Electroless Nickel Plating (ENP) – Provides uniform coating thickness on complex geometries with excellent hardness, wear resistance, and corrosion protection. Popular in aerospace, oil & gas, and precision engineering.
  • Passivation – Chemical treatment for stainless steel fasteners to enhance corrosion resistance by removing free iron and promoting the formation of a protective oxide layer (ASTM A967, AMS 2700).
  • Xylan & PTFE Coatings – Dry-film lubricant coatings combining low friction with corrosion protection. Ideal for high-torque, high-temperature, and anti-seize applications.

Self Colour Finish (Uncoated/Bright/As-Manufactured)

For applications where no specific protective coating is required, fasteners can be supplied in their 'self colour', 'bright', 'black', or 'as-manufactured' condition. This means the parts are supplied directly from production with only a light protective oil applied to prevent corrosion during transit and storage. Self colour finish is common for:

  • Indoor assemblies with low corrosion risk
  • Components that will be painted or coated post-assembly
  • High-tensile fasteners (Grade 10.9, 12.9) where coating is not recommended
  • Prototype and development work
  • Cost-sensitive applications

Note: Self colour finish provides minimal corrosion protection and is not recommended for outdoor, marine, or high-humidity environments.

Why Do We Plate or Coat Fasteners?

Applying protective coatings and finishes to fasteners delivers multiple engineering and operational benefits:

  • Forms a Protective Barrier – Many industrial electroplating processes create a sacrificial barrier on the substrate that protects the base metal against atmospheric corrosion, chemical attack, and galvanic reactions. Plated parts can last significantly longer, need less frequent replacement, and perform reliably under extreme conditions.
  • Prevents Corrosion & Oxidation – Zinc, zinc alloys, cadmium, and other coatings act as a sacrificial anode, corroding preferentially to protect the underlying steel. This is critical in marine, automotive, construction, and outdoor applications.
  • Reduces Friction & Prevents Galling – Coatings such as zinc-nickel, cadmium, and PTFE-based finishes improve lubricity, reduce installation torque, and prevent thread galling and seizing, particularly important in stainless steel assemblies.
  • Increases Hardness & Wear Resistance – Electroplating with nickel, electroless nickel, or hard chrome makes brittle or soft materials stronger and more durable. Plated surfaces are less susceptible to damage when struck, dropped, or subjected to abrasive environments, increasing component lifespan.
  • Increases Thickness & Build-Up – Certain plating processes, such as electroless nickel and copper, can be used to restore worn or undersized components, improve overall quality, and extend substrate longevity.
  • Enhances Appearance – Decorative finishes such as bright nickel, chrome, brass, and black oxide improve aesthetics for furniture, architectural fittings, consumer products, and point-of-sale displays. A cheaper way to achieve a premium appearance than manufacturing from solid precious metals.
  • Promotes Adhesion for Multi-Layer Coatings – Copper plating provides a smooth, uniform surface finish ideal as an undercoating to facilitate adhesion with additional coatings such as nickel or chrome in multi-layer systems.
  • Prevents Tarnishing – Some electroplating types protect against premature tarnishing in metals like brass, copper, and silver. Products such as silverware, electrical contacts, and decorative hardware retain their attractiveness and hold their value over time.
  • Conducts Electricity – Silver, gold, and nickel plating enhance electrical conductivity, making them indispensable in electronic components, PCB hardware, telecommunications equipment, and battery terminals. Cost-effective and efficient conductivity solutions.
  • Resists Heat – Plating processes such as gold, zinc-nickel, electroless nickel, and ceramic-based coatings can withstand extremely high temperatures. These protect engine parts, exhaust components, and industrial equipment from thermal damage, extending their operational lifespan.
  • Absorbs Light & Energy – Black electroless nickel and black oxide finishes absorb light and energy, ensuring compliance with industry standards in aerospace, automotive, aviation, optical instruments, and solar energy applications.
  • Ensures Standards Compliance – Many industries mandate specific coating standards (ISO, ASTM, BS, DIN, DEF STAN, AMS) for safety-critical applications in aerospace, automotive, rail, oil & gas, and defence sectors.

Why do we plate or coat fasteners?

Feature Benefit Description
Absorbs Light & Energy Ensures compliance with industry standards Black electroless nickel plating absorbs light and energy essential to many manufacturing processes in industries such as aerospace, automotive and aviation.
Conducts Electricity Cost effective and efficient conductivity solution Silver plating can be used to enhance electrical conductivity which makes it useful in the manufacture of electronic components.
Enhances Appearance A cheaper way to improve aesthetics Jewelry is often plated with a thin layer of a precious metal to make it more desirable.
Forms a Protective Barrier Plated parts can last longer and need to be replaced less frequently, and are more likely to hold up under extreme conditions. Many types of industrial electroplating create a barrier on the substrate that protects it against atmospheric conditions such as corrosion.
Increases Hardness Plated surfaces are less susceptible to damage when struck or dropped, which can increase their lifespan. Electroplating is sometimes used to make brittle materials stronger and more durable.
Increases Thickness It improves overall quality and increases longevity of the substrate. Palladium plating is becoming an increasingly popular choice in manufacturing processes where extreme thickness is required.
Prevents Tarnishing Products such as silverware retain their attractiveness and hold their value over time. Some types of electroplating protect against premature tarnishing in certain kinds of metals and also reduce the likelihood of scratching.
Promotes Adhesion It provides a smooth and uniform surface finish. Copper plating is an ideal solution for providing an undercoating that facilitates adhesion with additional coatings.
Reduces Friction Nickel plating improves performance and reduces premature wear and tear. Nickel plating can reduce the build-up of friction in certain materials such as electrical connectors.
Resists Heat Plating with these metals protect engine parts and components from damage caused by extreme temperatures, which can increase their lifespan. Plating processes such as gold or zinc-nickel are capable of withstanding extremely high temperatures.

Fastener Finishes Comparison Chart

FINISH TYPE CORROSION PROTECTION TYPICAL THICKNESS COST APPEARANCE BEST APPLICATIONS HYDROGEN EMBRITTLEMENT RISK TEMPERATURE RESISTANCE STANDARD
Hot-Dip Galvanising Excellent (1000+ hours NSS) 45-85µm Medium Dull grey, rough texture Outdoor structures, marine, infrastructure, M8 and above None < 200°C BS EN ISO 10684 / ISO 10684:2004 / ASTM A153 / ASTM F2329 / ASTM B695 / DIN EN ISO 10684 / BS EN ISO 1461
Zinc Electroplating (Clear) Good (96-240 hours NSS) 5-15µm Low Bright silver General engineering indoor applications decorative High (Grade 10+) < 100°C BS EN ISO 4042 / ISO 4042:2022 / ASTM B633 / ASTM F1941 / DIN 50961 (superseded) / BS 7371-4
Zinc Electroplating (Yellow) Very Good (240-480 hours NSS) 5-15µm Low Golden yellow Automotive outdoor equipment moderate corrosion High (Grade 10+) < 100°C BS EN ISO 4042 / ISO 4042:2022 / ASTM B633 / ASTM F1941 / DIN 50961 (superseded) / BS 7371-4
Zinc Electroplating (Black) Very Good (240-480 hours NSS) 5-15µm Low-Medium Matte black Military firearms tools aesthetic applications High (Grade 10+) < 100°C BS EN ISO 4042 / ISO 4042:2022 / ASTM B633 / ASTM F1941 / DIN 50961 (superseded) / BS 7371-4
Zinc Flake (GEOMET) Excellent (720-1000+ hours NSS) 6-12µm High Dull silver-grey Automotive aerospace high-tensile fasteners None < 300°C BS EN ISO 10683 / ISO 10683:2018 / No direct ASTM equivalent / DIN 50969 (superseded by ISO) / Proprietary: Dörken MKS / Delta-MKS
Phosphate (Manganese) Moderate (48-96 hours NSS) 5-20µm Low-Medium Dark grey-black Pre-paint high friction oil retention Low < 400°C ASTM A966 / ASTM D6968 / DIN 50938 / MIL-DTL-16232 Type M (Parkerising)
Phosphate (Zinc) Moderate (24-48 hours NSS) 2-8µm Low Grey Paint base rust prevention temporary protection Low < 200°C ASTM D6968 / ASTM B633 Type IV / DIN 50938 / MIL-DTL-16232 Type Z
Black Oxide Poor (8-24 hours NSS) 0.5-1µm Very Low Matte black Indoor decorative low reflection requires oil None < 150°C ASTM D769 / DIN 50938 / MIL-DTL-13924
Nickel Plating (Bright) Very Good (200-500 hours NSS) 12-25µm Medium-High Bright silver Electrical marine decorative Moderate < 400°C BS EN ISO 2081 / ISO 2081:2008 / ASTM B633 Type V / ASTM B689 / DIN 50966 / AMS 2423
Electroless Nickel Excellent (500-1000 hours NSS) 12-25µm High Uniform grey Complex shapes wear resistance aerospace Low < 400°C ISO 4527:2003 / ASTM B733 / ASTM B656 / DIN 50966 / AMS 2404 / MIL-DTL-26074
Tin Plating Good (100-200 hours NSS) 5-15µm Medium Bright silver Food processing electronics soldering Low < 230°C ISO 2093:1986 / ASTM B545 / DIN 8513 / MIL-DTL-46843
Chrome Plating Good (200-400 hours NSS) 5-15µm High Mirror bright Decorative wear resistance automotive trim High < 425°C ASTM B177 / ASTM B456 / DIN 50966 / AMS 2460
Passivation (Stainless) Excellent Chemical treatment only Low Natural steel finish Stainless steel enhancement clean appearance None Material dependent ASTM A967 / ASTM A380 / SAE AMS 2700 / AMS QQ-P-35
PTFE/Xylan Coating Moderate to Good 10-25µm High Various colours available Low friction anti-galling high temperature None Up to 260°C (PTFE) / 290°C (Xylan) Proprietary: Whitford Xylan / Chemours Teflon
Delta Protekt/Tone Excellent (720-1000+ hours NSS) 6-12µm High Silver-grey or coloured Alternative to zinc flake automotive None < 300°C Similar to BS EN ISO 10683 / DIN 50969 / Proprietary: Dörken Delta-Protekt / Delta-Tone
Self Colour/Bright Poor (0-8 hours NSS) Oil film only Lowest Natural steel (grey/silver) Indoor only cost-sensitive pre-paint None Material dependent N/A

NSS = Neutral Salt Spray testing per ISO 9227 / ASTM B117. Hours indicate typical red rust appearance.

Size Ranges & Thread Forms Available

At Trojan Special Fasteners, we can apply finishes to our complete manufacturing range:

  • Metric: M3, M4, M5, M6, M7, M8, M9, M10, M11, M12, M13, M14, M15, M16, M17, M18, M20, M22, M24, M25, M26, M27, M28, M30, M32, M33, M34, M35, M36, M38, M39, M40, M42, M45, M48, M50, M52, M56 in coarse, fine, extra fine, and hard-to-find pitches.
  • Imperial (BSW/BSF/BA): 2BA to 2" including 1/4", 3/16", 5/16", 3/8", 7/16", 1/2", 9/16", 5/8", 11/16", 3/4", 7/8", 1", 1.1/16", 1.1/8", 1.3/16", 1.1/4", 1.5/16", 1.3/8", 1.7/16", 1.1/2", 1.5/8", 1.3/4", 1.7/8", 2", 2.1/4", 2.1/2"
  • Unified (UNC/UNF): #8 to 2.1/4" including 1/4", 5/16", 3/8", 7/16", 1/2", 9/16", 5/8", 3/4", 7/8", 1", 1.1/8", 1.1/4", 1.3/8", 1.1/2", 1.3/4", 2", 2.1/4"

Both left-hand and right-hand threads available. Selected finishes available in oversize thread configurations.

Current Industry Standards for Fastener Finishes

We ensure all finishes comply with relevant international, European, British, and American standards:

ISO (International Organisation for Standardisation)

  • ISO 2081 – Electroplated nickel coatings
  • ISO 3892 – Conversion coating of metallic materials
  • ISO 4042 – Electroplated coatings systems for fasteners
  • ISO 4520 – Electroless nickel coatings
  • ISO 4524 – Metallic coatings - test methods for electroplated gold and gold alloy coatings
  • ISO 9587 – Stress relief to prevent hydrogen embrittlement (pre-plating)
  • ISO 9588 – Heat treatment to reduce hydrogen embrittlement (post-plating)
  • ISO 10683 – Non-electrolytic zinc flake coatings
  • ISO 10684 – Hot dip galvanised coatings on threaded fasteners

British Standards (BS / BS EN)

  • BS 729 – Hot dip galvanised coatings on iron and steel articles
  • BS 1706 – Electroplated coatings of cadmium and zinc on iron and steel
  • BS 3382 – Electroplated coatings on threaded components
  • BS 7371 (Parts 1-7) – Coatings on metal fasteners
  • BS EN ISO 4042 – Electroplated coating systems
  • BS EN ISO 10683 – Zinc flake coatings
  • BS EN ISO 10684 – Hot dip galvanised coatings

ASTM (American Society for Testing and Materials)

  • ASTM A153 – Zinc coating (hot-dip) on iron and steel hardware
  • ASTM B487 – Measurement of metal and oxide coating thickness by microscopical examination
  • ASTM B545 – Electrodeposited coatings of tin
  • ASTM B633 – Electrodeposited zinc coatings on iron and steel
  • ASTM B695 – Zinc (hot-dip galvanised) coatings on iron and steel hardware
  • ASTM B849 – Pre-treatments of iron or steel for reducing risk of hydrogen embrittlement
  • ASTM F1940 – Process control verification to prevent hydrogen embrittlement
  • ASTM F1941 – Electrodeposited coatings on threaded fasteners
  • ASTM F2329 – Zinc coating, hot-dip, for bolts, screws, washers, nuts

SAE (Society of Automotive Engineers)

  • SAE J429 – Mechanical and material requirements for externally threaded fasteners
  • SAE AMS 2700 – Passivation of stainless steel

DIN (Deutsches Institut für Normung - German Standards)

  • DIN 267 (Parts 1-28) – Fasteners - Technical specifications
  • DIN 50961 – Electroplated zinc coatings on iron materials
  • DIN 50969 – Non-electrolytic zinc flake coatings
  • DIN 50979 – Corrosion protection of threaded fasteners

Obsolete, Withdrawn & Superseded Standards

Many older standards remain referenced in legacy drawings, maintenance manuals, and long-lifecycle industries. We maintain expertise in these discontinued specifications:

British Standards (Withdrawn/Obsolete)

  • BS 729:1971 – Superseded by BS EN ISO 1461
  • BS 1706:1990 – Superseded by BS EN ISO 2081 and BS EN ISO 4042
  • BS 3382:1973 – Superseded by BS EN ISO 4042
  • BS 3382-1:1991 – Withdrawn, replaced by BS EN ISO 4042
  • BS 7371-1:1991 to BS 7371-6:1998 – Superseded by BS EN ISO 10684 and BS EN ISO 4042

ASTM (Withdrawn Standards)

  • ASTM A490 – High-strength structural bolts (Replaced by ASTM F3125)
  • ASTM F1136/F1136M-11(2019) – Zinc/aluminium corrosion protective coatings (Withdrawn 2025)
  • ASTM F2280-14 – "Twist off" type tension control bolts (Withdrawn 2016)
  • ASTM F2403-09 – Machine screws, carbon steel, 60,000 psi (Withdrawn 2016)
  • ASTM F2674-07 – Zinc coating, hot-dip, metric fasteners (Withdrawn, superseded by F2329)
  • ASTM F2833-11(2017) – Corrosion protective coatings with zinc rich base (Withdrawn 2025)
  • ASTM F3019/F3019M-19 – Chromium-free zinc-flake composite (Withdrawn 2025)
  • ASTM F436M-11 – Hardened steel washers metric (Withdrawn 2016)
  • ASTM F568M-07 – Carbon and alloy steel externally threaded metric fasteners (Withdrawn 2012)
  • ASTM F835M-11 – Socket button and flat countersunk head cap screws metric (Withdrawn 2015)
  • ASTM F871M-98 – Electrodeposited coatings on threaded components [Metric] (Withdrawn 2001)
  • ASTM F912M-11 – Alloy steel socket set screws metric (Withdrawn 2015)
  • ASTM F959M-13 – Compressible-washer-type direct tension indicators metric (Withdrawn 2016)

DIN (Superseded by ISO/EN)

  • DIN 267 parts – Superseded by EN/ISO equivalents
  • DIN 50961 – Largely superseded by ISO 4042
  • Many individual DIN fastener standards replaced by ISO equivalents

International Obsolete Specifications

  • MIL-DTL-16232 – Cadmium plating (low hydrogen embrittlement) - Largely replaced by AMS-QQ-P-416
  • MIL-F-495 – Cadmium or zinc coating on ferrous fasteners (Obsolete)

Note: If your drawings reference any obsolete or withdrawn specifications, please contact our technical team. We maintain extensive cross-reference databases and can identify modern equivalent standards or re-create obsolete finishes where technically feasible and commercially viable.

Material Compatibility & Substrate Considerations

Not all finishes are suitable for all base materials. Critical compatibility factors include:

  • Alloy Steel (Grade 8, 10, 12) – Hydrogen embrittlement risk with electroplating; zinc flake coatings preferred for Grade 10 and above
  • Aluminium – Anodising, chemical film (Alodine), or dry-film lubricants
  • Brass & Bronze – Limited coating options; typically polished or lacquered
  • Carbon Steel – Compatible with most finishes (zinc, galvanising, phosphating, nickel, chrome, black oxide)
  • Stainless Steel (303, 304, 316, A1, A2, A4) – Typically passivated rather than plated; PTFE/Xylan coatings for anti-galling

Hydrogen Embrittlement Prevention

High-tensile fasteners (hardness ≥320 HV, typically Grade 10.9, 12.9, and case-hardened components) are susceptible to hydrogen embrittlement during electroplating processes. To mitigate this risk:

  • Specify zinc flake coatings (GEOMET®, Magni, Dacromet®) which eliminate hydrogen absorption
  • Request baking/de-embrittlement heat treatment within 4 hours of plating (per ISO 9588, ASTM F1940, DIN 50969-2)
  • Use mechanically applied coatings (hot-dip galvanising, zinc flake) instead of electroplating
  • Specify lower-strength substrates where possible
  • Request process certification and batch testing

Important: Even with baking, electroplating cannot completely eliminate hydrogen embrittlement risk in high-tensile fasteners. For safety-critical applications, specify zinc flake or mechanical coatings.

Coating Thickness & Thread Tolerances

Coating application increases the effective diameter of external threads and decreases internal thread diameters. Typical coating thicknesses:

  • Electroplated Zinc: 5-15 microns (0.0002"-0.0006")
  • Hot-Dip Galvanising: 45-85 microns (0.0018"-0.0033")
  • Zinc Flake: 6-12 microns (0.00024"-0.00047")
  • Electroless Nickel: 12-25 microns (0.0005"-0.001")
  • Cadmium: 5-12 microns (0.0002"-0.0005")

To maintain thread gaugeability after coating, we can supply:

  • Oversize external threads – Pre-plating undersize manufacturing
  • Oversize tapped nuts – Post-coating tapping to restore thread fit
  • Thread class adjustments – Specifying appropriate tolerance class for coated fasteners

Consult our technical team for coating thickness recommendations for your specific assembly torque requirements.

Industries We Serve with Fastener Finishing

  • Aerospace & Aviation
  • Agricultural Equipment
  • Architectural Ironmongery
  • Automotive & Heavy Vehicle
  • Construction & Infrastructure
  • Defence & Military
  • Electronics & Telecommunications
  • Food Processing & Pharmaceutical (stainless steel passivation, tin plating)
  • Furniture & Joinery
  • Marine & Offshore
  • Mining & Quarrying
  • Oil & Gas
  • Power Generation & Renewable Energy
  • Rail & Transportation

Quality Assurance & Testing

All finishes applied through our subcontractor network undergo rigorous quality control:

  • Salt spray testing (NSS) to ISO 9227, ASTM B117
  • Coating thickness measurement by XRF, magnetic induction, or microscopic cross-section
  • Adhesion testing per ISO 2819, ASTM B571
  • Torque-tension testing for lubricated coatings
  • Hydrogen embrittlement testing per ISO 15330, ASTM F1940
  • Visual inspection for surface defects, coverage, colour matching
  • Batch sampling and certification per ISO 2859, MIL-STD-105

Full material traceability and certification available upon request; please request this at the quotation and order stages.

Frequently Asked Questions About Fastener Finishes

Q: What is the best finish for outdoor applications?

A: Hot-dip galvanising (ISO 10684) or zinc flake coatings (ISO 10683) offer the longest service life in outdoor, marine, and corrosive environments. For structural fasteners, hot-dip galvanising is typically specified to BS EN ISO 1461.

Q: Can high-tensile fasteners (Grade 10, 12) be zinc plated?

A: Electroplated zinc is not recommended for Grade 10 and above due to hydrogen embrittlement risk. Specify zinc flake coatings (GEOMET®, Magni) or mechanical galvanising instead. If electroplating is essential, rigorous baking and testing per ISO 9588 and ASTM F1940 are mandatory.

Q: How do I specify a coating on my drawings?

A: Use standard callouts such as "Zinc Plate per ISO 4042 – Fe/Zn 8 c" or "Hot Dip Galvanise per ISO 10684". Include coating thickness, passivation type (clear, yellow, black), and any special requirements (e.g., "with post-plate baking" or "tap oversize").

Q: What is the difference between galvanising and zinc plating?

A: Zinc plating is an electroplated coating (5-15 microns) applied in a bath, offering good corrosion protection and tight dimensional control. Galvanising is a hot-dip process (45-85 microns minimum) providing a much thicker, more durable coating for long-term outdoor use, but with rougher surface texture and looser tolerances.

Q: Are all finishes available on all fastener sizes?

A: Most finishes are available across our full M3-M52 metric and 2BA-2" imperial range. However, some processes have practical limitations – for example, hot-dip galvanising is not recommended below M8 due to thread fill issues, and some specialist coatings may have minimum batch quantities. Contact us to confirm availability for your specific requirement.

Q: What is the lead time for finished fasteners?

A: Standard finishes (zinc plate, galvanising, phosphate) typically add 7-14 days to manufacturing lead time. Specialist coatings (zinc flake, electroless nickel) may require 3-4 weeks depending on subcontractor scheduling and batch consolidation. Urgent requirements can often be accommodated – please enquire.

Q: Can you match a finish from a sample or competitor product?

A: Yes, send us a sample and we'll analyse the coating type, thickness, colour, and texture to replicate it. We can cross-reference competitor specifications and provide equivalent or superior alternatives.

Q: Do you provide certification and test reports?

A: Yes, we can provide full material traceability certificates, coating thickness reports, salt spray test results, torque-tension data, and compliance declarations to customer-specific or industry standards. Specify certification requirements at quotation stage.

Q: What if I need a finish not listed on this page?

A: We work with a network of specialist subcontractors offering exotic coatings including PTFE (Xylan), ceramic, silver, gold, electroless nickel, anodising (aluminium), and bespoke multi-layer systems. Contact our technical team with your requirement.

Q: Can stainless steel fasteners be plated?

A: Stainless steel is typically passivated (ASTM A967, AMS 2700) rather than plated to enhance the natural corrosion resistance. For lubricity and anti-galling properties, dry-film lubricants (PTFE, Xylan) are recommended. Electroplating stainless steel requires special surface preparation and is rarely specified.

Q: What is 'yellow zinc' versus 'clear zinc'?

A: Both refer to zinc plated fasteners with different chromate passivation topcoats. Clear (also called 'blue' or 'bright') offers moderate corrosion resistance with a silvery appearance. Yellow (also called 'gold' or 'dichromate') provides enhanced corrosion protection with a golden-yellow tint. Black chromate offers the best corrosion resistance with a dark appearance. Note: Traditional hexavalent yellow chromate is now largely replaced by RoHS-compliant trivalent chromates.

Q: Are your finishes RoHS and REACH compliant?

A: Yes, all standard finishes comply with RoHS (Restriction of Hazardous Substances) and REACH (Registration, Evaluation, Authorisation of Chemicals) regulations. We no longer use hexavalent chromium passivations except where specifically required by legacy aerospace/defence approvals.

Q: How do I prevent galling with stainless steel fasteners?

A: Galling (cold welding) is common with stainless steel-on-stainless assemblies. Solutions include: dry-film lubricants (PTFE/Xylan), silver plating, copper-based anti-seize, wax coatings, or using dissimilar materials (e.g., stainless bolt with bronze nut). Reduce installation torque and use controlled tightening procedures.