Materials & grades
Materials, finishes & grades
Which finish survives three miles from the Atlantic.
Coastal reality
Which metal survives here
Three miles from the Atlantic, the finish matters as much as the size. This is where the cheap fastener costs you the most.
| Finish | Use it for | How it holds up |
|---|---|---|
| Zinc plated | Indoors, dry, out of sight | Rusts outdoors in a season near the coast |
| Hot-dip galvanized | Outdoor framing, fencing, treated lumber | Years outdoors; the thick coating is what protects it |
| 304 stainless | General outdoor use, docks a few blocks inland | Excellent, may tea-stain in direct salt spray |
| 316 marine stainless | Oceanfront, docks, boats, pool areas | The right answer on the barrier island |
| Brass / bronze | Decorative hardware, marine trim | Soft — decorative strength only |
| Bolt grade | Head marking | Strength |
|---|---|---|
| Grade 2 | No marks on the head | Basic. General light-duty assembly. |
| Grade 5 | Three radial lines | Medium-high. Automotive and general construction. |
| Grade 8 | Six radial lines | High. Suspension, towing, structural. |
| Stainless 18-8 | Often marked A2 / 304 | Corrosion first, strength second. |