Fastener Q&A: What Is The Difference Between Electro‑Galvanized And Hot‑Dip Galvanized Fasteners
Many overseas customers often get confused when choosing zinc‑plated fasteners. We sort out the most frequently asked technical questions about two mainstream galvanizing processes for industrial bolts and screws.
Question 1: What is electro‑galvanizing for fasteners?
Electro‑galvanizing is an electrolytic surface treatment that forms a thin zinc coating on the fastener surface. It features a bright and smooth appearance with a thin zinc layer, suitable for indoor dry working environments.
Question 2: What is hot‑dip galvanizing for bolts?
- Hot‑dip galvanizing immerses cleaned fasteners into molten zinc liquid to form a thick zinc alloy protective layer
- It delivers excellent salt‑spray and anti‑corrosion performance for outdoor and coastal projects
- The thicker zinc layer may slightly change thread size, requiring matching over‑size nuts during assembly
- The surface finish is matte silver grey instead of bright polished appearance
Parameter & Application Comparison Table
| Galvanizing Type | Zinc Coating Thickness | Salt Spray Resistance | Best Application Scenario |
| Electro‑galvanized | 5‑15 μm | 24‑72 hours | Indoor machinery, cabinet and general assembly |
| Hot‑dip galvanized | 45‑85 μm | 500‑1000 hours | Outdoor construction, bridge, coastal and marine projects |
Practical Purchase Suggestion： If your project works in humid, coastal or outdoor environments, hot‑dip galvanized fasteners are recommended. For indoor equipment with high requirements for surface appearance, electro‑galvanized screws will be the better choice. You can send us your project environment requirements, and our technical team will recommend the most cost‑effective fastener surface treatment for you.