4 min read
Zinc vs Stainless Fasteners
Two of the most common finishes — but they behave very differently when the weather turns.
Zinc-plated steel fasteners are inexpensive and offer moderate corrosion resistance for indoor and protected outdoor use. The zinc layer is sacrificial — it corrodes preferentially to protect the steel underneath — but once it's gone, the bolt rusts fast.
Stainless steel fasteners (typically 18-8 or 316) resist corrosion through a chromium-oxide layer that re-forms when scratched. They cost 3–5× more than zinc but last decades in wet, salty, or chemical environments.
Rule of thumb: indoor and dry → zinc. Outdoor, marine, food-grade, or chemical exposure → stainless. And never mix zinc and stainless in a wet joint — galvanic corrosion will eat the zinc.
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