Overview
Choosing the right finish is critical for fastener longevity. The wrong finish in a corrosive environment can lead to premature failure, safety issues, and costly repairs.
Quick Comparison
| Finish | Corrosion Resistance | Best For | Relative Cost |
|---|---|---|---|
| Zinc Plated | Low-Medium | Indoor, light outdoor | $ |
| Hot-Dip Galvanized | Medium-High | Outdoor, structural | $$ |
| 18-8 Stainless | High | Wet, food, marine | $$$ |
| 316 Stainless | Very High | Coastal, chemical | $$$$ |
Zinc Plated
Electroplated zinc coating, typically 5-12 microns thick. The most common and economical finish.
- Best for: Indoor use, dry environments, temporary outdoor use
- Avoid for: Long-term outdoor exposure, wet environments
- Lifespan outdoor: 1-3 years before visible rust
Hot-Dip Galvanized
Fasteners are dipped in molten zinc, creating a thick coating (50+ microns) that's metallurgically bonded to the steel.
- Best for: Outdoor structural, fencing, decks, bridges
- Avoid for: Marine/coastal (use stainless instead)
- Lifespan outdoor: 20-50+ years
- Note: Threads may be oversized—use galvanized nuts
18-8 Stainless Steel
An alloy containing 18% chromium and 8% nickel (also called 304 stainless). Inherently corrosion resistant—no coating to wear off.
- Best for: Food equipment, marine (light duty), architectural
- Avoid for: Direct saltwater exposure, chlorine environments
- Note: Lower strength than Grade 5/8 steel
316 Stainless Steel
Contains molybdenum for superior corrosion resistance, especially in chloride environments.
- Best for: Coastal/marine, pools, chemical plants
- Cost: Significantly more than 18-8
- Note: Worth the cost for coastal Georgia applications
For Georgia Outdoor Use
Georgia's humidity accelerates corrosion. Our recommendations:
- Inland outdoor: Hot-dip galvanized (minimum)
- Near coast (within 20 miles): 316 stainless
- Direct coastal exposure: 316 stainless only