What Is Zinc Flake Coating?
Zinc flake coating is a protective surface treatment that helps prevent steel from rusting. Unlike traditional zinc electroplating, the process does not use an electrical current to deposit zinc onto the component.
Most zinc flake systems contain tiny zinc and aluminium flakes within a special binder. The manufacturer applies the coating to the steel surface and then cures it under controlled conditions.
Once the coating cures, the overlapping metal flakes form a protective layer. This layer helps slow down corrosion in two ways:
- Barrier protection: The overlapping flakes help prevent moisture and corrosive substances from reaching the steel surface.
- Sacrificial protection: Zinc corrodes preferentially to steel and helps protect the underlying material.
As a result, zinc flake coatings can provide strong corrosion protection without requiring a thick coating. This makes them useful for fasteners, clamps, brackets and other components where accurate dimensions matter.
How Does Zinc Flake Coating Work?
Manufacturers use several methods to apply zinc flake coatings. The exact process depends on the coating system and the shape of the component.
- Surface preparation: The manufacturer cleans the steel to remove dirt, grease and other contaminants.
- Coating application: The manufacturer applies the zinc flake material using methods such as spraying or dip-spin coating.
- Curing: Controlled heat helps the coating form a durable protective layer.
- Additional protection: Some systems use extra coating layers or topcoats to improve performance.
- Quality checks: The manufacturer checks coating thickness, adhesion and other required properties.
Unlike electroplating, the zinc flake application process does not generate hydrogen through electrical deposition. Therefore, it can help reduce hydrogen embrittlement risks for certain high-strength fasteners. However, manufacturers must still control the complete production process.
What Is GEOMET Coating?
GEOMET® is a proprietary zinc flake coating technology from NOF Metal Coatings. It uses a water-based, chromium-free system to protect steel components against corrosion.
The coating contains zinc and aluminium flakes within a specialised binder. Together, these materials provide barrier and sacrificial protection.
Key Features of GEOMET
- Chromium-free zinc flake coating technology.
- Water-based coating system.
- Non-electrolytic application process.
- Relatively thin protective layer.
- Corrosion protection for suitable steel components.
- Optional topcoats for specific performance requirements.
GEOMET coatings appear in several industries, including automotive manufacturing, construction and mechanical engineering. In addition, manufacturers use them on selected fasteners, clamps and cable containment accessories.
GEOMET is a specific coating technology rather than a general name for every zinc flake finish.
What Is DACROMET Coating?
DACROMET® is an established zinc flake coating technology associated with NOF Metal Coatings. Manufacturers have used it for corrosion protection on fasteners and other metal components.
Traditional DACROMET formulations contain chromium compounds, including hexavalent chromium chemistry. In contrast, GEOMET uses chromium-free technology.
Environmental and product regulations have encouraged the development and adoption of chromium-free coating systems. Consequently, GEOMET and other chromium-free technologies have become important alternatives in many industries.
GEOMET vs DACROMET: Comparison
| Feature | GEOMET | DACROMET |
|---|---|---|
| Coating family | Zinc flake | Zinc flake |
| Technology | Chromium-free system | Earlier chromium-containing system |
| Application | Non-electrolytic | Non-electrolytic |
| Corrosion protection | High when correctly specified | High when correctly specified |
| Common uses | Fasteners, clamps and industrial components | Industrial fasteners and metal components |
Both technologies provide zinc-based corrosion protection. However, their chemical formulations differ. The exact coating specification determines the performance of each system.
Zinc Flake vs Hot Dip Galvanising (HDG)
Hot dip galvanising protects steel by immersing prepared components in molten zinc. The process creates a zinc coating that bonds to the steel surface.
Zinc flake coating uses a different approach. Instead of dipping steel into molten zinc, manufacturers apply a coating containing zinc and aluminium flakes before curing it.
Both methods help protect steel against corrosion. However, they differ in coating thickness, application and typical uses.
Zinc Flake vs HDG Comparison
| Feature | Zinc Flake | HDG |
|---|---|---|
| Application | Applied and cured coating | Immersion in molten zinc |
| Typical thickness | Often around 6–15 microns | Often several tens of microns or more |
| Corrosion resistance | Depends on coating system | Depends on zinc thickness and environment |
| Thread tolerance | Well suited to close tolerances | May require thread allowances |
| Common uses | Clamps, fasteners and smaller components | Strut channels, supports and structural steel |
The figures above show common coating ranges rather than fixed specifications. Manufacturers may use different thicknesses to meet particular standards.
Which Is Better: Zinc Flake or HDG?
Neither finish offers the best solution for every installation.
Zinc flake can provide strong corrosion protection on smaller components while maintaining relatively thin coating dimensions. Therefore, manufacturers often choose it for specialist clamps and fasteners.
HDG provides a substantial zinc coating and remains a common choice for structural supports, strut channels and outdoor steelwork.
For example, an installation may use HDG strut channel alongside zinc flake-coated fixings. However, installers should assess the corrosion resistance and compatibility of the complete assembly.
Zinc Flake vs Bright Zinc Plated (BZP)
Bright Zinc Plated (BZP) is a widely used finish for nuts, bolts, washers, threaded rods and general construction fixings.
The electroplating process deposits a layer of zinc onto steel. Manufacturers often add passivation to improve corrosion protection and appearance.
Although BZP and zinc flake both use zinc-based protection, their coating processes differ.
| Feature | Zinc Flake | BZP |
|---|---|---|
| Process | Non-electrolytic coating | Electroplating |
| Appearance | Often grey or silver | Typically bright silver |
| Corrosion resistance | Can provide high protection | Depends on plating and passivation |
| Hydrogen embrittlement | Low risk from coating deposition | Requires controls for susceptible steels |
| Typical uses | Specialist clamps and fasteners | General-purpose nuts, bolts and rods |
Is Zinc Flake Better Than BZP?
Many high-performance zinc flake systems offer greater corrosion protection than basic BZP finishes. However, the exact result depends on the coating specification, thickness and testing requirements.
BZP remains a practical and economical choice for many dry internal installations. In contrast, a suitable zinc flake system may provide additional protection in more demanding conditions.
Can Zinc Flake and HDG Be Used Together?
Yes, zinc flake-coated components can often work alongside hot dip galvanised steel. However, the complete assembly must meet the installation requirements.
For example, a cable containment system may combine:
- Hot dip galvanised strut channel.
- Zinc flake-coated suspension clamps.
- Compatible threaded rods, nuts and washers.
Both finishes use zinc-based corrosion protection. Nevertheless, this does not guarantee equal performance across every component.
Before combining finishes, consider moisture, salt exposure, coating damage, load requirements and the expected service conditions.
Can Zinc Flake and BZP Be Used Together?
Zinc flake and BZP components can often work together when their dimensions and fixing arrangements match.
For example, an installer may use a zinc flake-coated clamp with a compatible BZP threaded rod.
However, the BZP component may offer less corrosion resistance than the zinc flake-coated clamp. Consequently, the threaded rod could become the first part of the assembly to show corrosion in a damp environment.
Therefore, installers should choose every component according to the expected exposure conditions rather than relying on the protective finish of one part.
Can Zinc Flake Be Used with Stainless Steel?
Some installations combine zinc flake-coated steel with stainless steel components. However, mixed-metal corrosion requires careful consideration.
When dissimilar metals make electrical contact in the presence of moisture, galvanic corrosion may occur.
Zinc is generally more anodic than stainless steel. As a result, zinc-based coatings may corrode preferentially under suitable conditions.
The level of risk depends on moisture, salt exposure, component size and the design of the assembly.
For coastal, chemical or persistently wet environments, installers should follow the relevant project specification and seek appropriate technical guidance.
Does Zinc Flake Coating Prevent Rust?
Zinc flake coatings help delay corrosion, but no protective finish can guarantee complete protection in every environment.
Several factors affect coating performance:
- Coating type and thickness.
- Surface preparation and application quality.
- Additional protective topcoats.
- Exposure to moisture, salt and chemicals.
- Mechanical wear and installation damage.
- Maintenance and operating conditions.
Manufacturers often use salt spray testing, including tests under ISO 9227, to assess corrosion performance.
However, salt spray test hours do not translate directly into years of outdoor service life. Actual performance depends on the environment and the complete coating system.
Where Is Zinc Flake Coating Used?
Cable Basket Suspension Systems
Suspension clamps and hanging plates support wire cable baskets from threaded rods. Zinc flake finishes can provide corrosion protection while maintaining accurate component dimensions.
Flange Clamps and Beam Fixings
Zinc flake-coated flange clamps provide fixing options for compatible beam-mounted support systems. Installers use these components in cable containment, pipework and other building services applications.
Concrete Anchors and Throughbolts
Selected throughbolts use zinc flake coatings for corrosion protection. However, installers must always follow the manufacturer’s approved load ratings, substrates and installation instructions.
Cable Tray Accessories
Specialist cable tray accessories can also use zinc flake finishes. These coatings help protect smaller steel components used in cable containment systems.
Zinc Flake and GEOMET Products at Direct Channel
Direct Channel Support Systems supplies a range of specialist clamps, suspension supports and fixing products with protective zinc flake finishes.
The range includes products with genuine GEOMET coating as well as products with other zinc flake finishes.
GEOMET Suspension Clamps
Our GEOMET suspension clamps provide practical support options for compatible wire cable basket installations.
M6 Suspension Clamp Central Support – GEOMET Zinc Flake Finish
Designed for M6 threaded rods, this hanging plate supports central and paired wire basket suspension arrangements.
M8 Suspension Clamp Central Support – GEOMET Zinc Flake Finish
Suitable for M8 threaded rods, this support clamp provides a practical fixing option for overhead wire cable basket installations.
Zinc Flake Flange Clamps
Our zinc flake flange clamps provide fixing solutions for compatible steel beams and support systems.
Zinc Flake Concrete Throughbolts
Selected Rawlplug throughbolts feature zinc flake protective finishes for suitable anchoring applications.
- M8 x 80mm Zinc Flake Throughbolt
- M10 x 65mm Zinc Flake Throughbolt
- M12 x 80mm Zinc Flake Throughbolt
- M16 x 140mm Zinc Flake Throughbolt
Frequently Asked Questions
Is zinc flake the same as galvanised steel?
No. Zinc flake coating and hot dip galvanising use different processes. Both provide zinc-based corrosion protection, but their coating structures and typical applications differ.
Is GEOMET the same as DACROMET?
No. Both belong to the zinc flake coating family. However, GEOMET uses chromium-free technology, while traditional DACROMET formulations contain chromium compounds.
Is zinc flake coating suitable for outdoor use?
Some zinc flake systems are suitable for outdoor applications. However, the coating specification and expected environmental conditions determine suitability.
Can I use a zinc flake clamp with BZP threaded rod?
Often yes, provided the components are mechanically compatible and the complete assembly meets the required corrosion and loading specifications.
Can zinc flake fixings be used with HDG cable tray?
Yes, in many applications. However, installers should check mechanical compatibility, environmental exposure and the relevant project requirements.
Is zinc flake better than stainless steel?
Not necessarily. Zinc flake is a protective coating, while stainless steel is a corrosion-resistant material. The best choice depends on the environment, material grade and installation requirements.
Does zinc flake coating contain chromium?
It depends on the system. GEOMET uses chromium-free technology, while traditional DACROMET formulations contain chromium compounds.
What standards apply to zinc flake coatings?
ISO 10683 covers non-electrolytically applied zinc flake coating systems for fasteners. In addition, ISO 9227 describes salt spray corrosion testing. Other standards may apply depending on the product and application.
Conclusion: Choosing the Right Protective Finish
Zinc flake coating provides an effective way to protect steel components against corrosion while maintaining relatively thin coating dimensions.
GEOMET and DACROMET are established technologies within this coating family. However, their formulations and performance specifications differ.
Compared with basic BZP finishes, suitable zinc flake systems can offer greater corrosion resistance. Meanwhile, HDG remains a common choice for larger steel supports and structural components.
For cable containment installations, the right finish depends on the complete assembly. Therefore, contractors should consider threaded rods, clamps, channels and fixings together rather than selecting each component in isolation.
Need Help Choosing the Right Finish?
Direct Channel Support Systems supplies cable containment products, threaded rods, brackets, clamps and specialist fixings for commercial and industrial installations.
For product advice, bulk quantities or trade pricing, contact our team.
Telephone: 0121 270 8507
Email: orders@directchannel.uk.com
