What galvanic corrosion is
When two dissimilar metals are in direct contact with moisture present, an electrochemical reaction accelerates corrosion of the less noble metal — so a mild steel bolt in a stainless railing corrodes faster than it would on its own, staining and weakening the joint.
Why it shows up at fixings first
Fixings are where dissimilar metals most often meet, and base plates are where moisture most often collects — which is exactly why our base plate guide emphasises matched fasteners alongside sealing.
The straightforward prevention
- Use stainless fasteners with stainless fabrication — matched grade where possible
- Isolate dissimilar metals with a non-conductive washer or gasket where contact is unavoidable
- Keep the joint sealed so moisture can't sit in the contact zone
What to ask your fabricator
Simply ask what grade the fasteners are. A fabricator who's thought about this will answer specifically — and if the answer is vague, that's worth pressing on, since this is a genuinely common cause of premature corrosion complaints.