Glossary

PFAS-free zinc flake coatings are corrosion-protective fastener finishes that use thin zinc and/or aluminum flakes in a binder system, but are formulated without PFAS chemicals, often called “forever chemicals.” PFAS stands for per- and polyfluoroalkyl substances, a broad family of fluorinated chemicals known for resisting heat, oil, water, and chemical attack, but also for environmental persistence and growing regulatory concern.

In fastener applications, zinc flake coatings are commonly used as an alternative to electroplated zinc, especially where high corrosion resistance is needed without introducing hydrogen embrittlement risk from acid pickling or electroplating. The coating is typically applied by dip-spin, spray, or rack process, then cured. Instead of forming a solid metallic zinc deposit like plating, the finish creates a layered barrier of overlapping metallic flakes. Those flakes act a bit like roof shingles, making it harder for moisture, oxygen, and salts to reach the steel underneath.

A PFAS-free version means the coating system avoids fluorinated additives that may have historically been used to improve lubricity, water repellency, release properties, chemical resistance, or friction control. This matters because many manufacturers and end users are moving away from PFAS-containing materials due to environmental, health, and compliance pressures.

For fasteners, the challenge is that the coating still has to do several jobs at once: resist corrosion, maintain consistent torque-tension behavior, avoid galling or seizing, meet coefficient-of-friction requirements, survive handling, and remain compatible with mating parts. A good PFAS-free zinc flake coating should still provide strong salt spray performance and predictable assembly behavior, but the formulation may rely on non-fluorinated lubricants, sealers, or topcoats to replace what PFAS-containing chemistry used to provide.

In plain fastener terms: PFAS-free zinc flake coatings are modern corrosion-resistant finishes designed to protect bolts, nuts, washers, and other steel parts while reducing reliance on persistent fluorinated chemicals. They are especially relevant for automotive, heavy equipment, construction, energy, and industrial applications where corrosion performance and compliance requirements both matter.

Zinc flake coating is a non-electrolytic finish made of zinc and aluminum flakes in a binder, applied by spraying or dipping and then cured with heat. Despite being thin, it offers very high corrosion resistance, often exceeding 1,000 hours in salt spray testing. It eliminates the risk of hydrogen embrittlement, making it especially suitable for high-strength fasteners and critical applications in industries like automotive and aerospace.

Blog Post: What Are Zinc Flake Coatings and Why Are They Important