Rust kills fasteners. The coating protects the steel underneath. Here's how the main options compare in plain terms.
Electroplated zinc
Cheapest option. 5-25 microns thick. Fine for indoor use, maybe sheltered outdoor. It chips if you over-tighten. Not suitable for anything exposed to moisture long-term.
Hot-dip galvanizing
Zinc bath treatment. 40-100+ microns, metallurgically bonded to steel. The go-to for outdoor structural work. Will last decades in normal environments. The tradeoff: thickness can affect thread fit on small fasteners — check the thread engagement if you're using small diameters.
DACROMET
Zinc and aluminum flake in a water-based carrier. Thin (8-12 microns) but performs like much thicker coatings in salt spray tests. Biggest advantage: doesn't cause hydrogen embrittlement. That matters for high-strength bolts (grade 10.9 and up). Used heavily in automotive and structural applications where strength is critical.
Zinc-nickel plating
Electroplated with 10-15% nickel. Better corrosion resistance than plain zinc, thinner than hot-dip. A good middle ground for outdoor use where hot-dip is overkill.
How to pick
- Indoor dry: electroplated zinc
- Outdoor general: hot-dip galvanizing or zinc-nickel
- Coastal or chemical exposure: stainless or DACROMET
- High-strength structural bolts: DACROMET only — plain zinc causes hydrogen embrittlement
Need Help Choosing the Right Coating?
Our technical team can recommend the optimal surface treatment for your specific application environment.
Submit Inquiry →