Galvanized steel is a popular option for the cost-conscious engineer. The main thing that makes it attractive is that it includes zinc to improve durability and corrosion resistance.
There are other benefits too -- no wonder it’s the budget material of choice for many projects. But did you know that there are different methods used to galvanize steel? Two of the most widely used, electrogalvanization (aka cold galvanization) and hot dipped galvanization, produce significantly different final products.
When you’re comparing hot dipped galvanized vs. galvanized steel made in other ways, remember each method has its advantages. When choosing galvanized steel, make sure you know which galvanization method is used so you get a product that suits your needs.
‘Hot Dipped’ Galvanized vs Galvanized: Advantages and Disadvantages
Hot Dipped Galvanized Steel
Hot dipped galvanization is exactly what it sounds like -- the material is dipped in a molten bath of zinc to coat the material. Before that, the material is put through a rigorous, 7-step cleaning process using caustic materials to ensure the metal is primed for zinc bonding.
Hot dipping in zinc produces a thick, durable galvanization, one you can depend on to stand up to outdoor and heavy use.
Advantages of hot dipped galvanization are numerous:
- Lasts significantly longer than electro galvanization
- Standard coating is up to 10x thicker than coating produced by electrogalvanization
- Hot dipping creates a pure zinc exterior coating and an iron-zinc alloy on the steel’s surface. The alloy created is strong enough to stand up to many types of impact.
- Can be used to pregalvanize materials before assembly, including steel sheets, wire, and tubing. Can also be used to batch galvanize fully fabricated items.
Electrogalvanization is done by immersing steel in a bath of saline and zinc. Electricity is applied to the solution, which causes electrons from the zinc to bond to the steel. The zinc forms a layer on top of the steel that protects against corrosion.
The process gives your material a smooth, attractive finish. However, that finish won’t be nearly as durable as a finish produced by hot dip galvanization.
Advantages of electro galvanization include:
- More cost-effective than hot dipped galvanization
- The coating produced is uniform
- Leaves a clean finish that is attractive and appropriate for architectural applications where aesthetics are a priority
What Do You Value?
Hot dipped galvanization can produce a material that’s extremely durable, with a thick coating of zinc that’ll stand up to abrasions and weathering in a way electrogalvanization can’t match. However, the beautiful finish produced by electrogalvanization is impossible with hot dipping.
The process you choose should depend on whether you prioritize durability or appearance. (In life, doesn’t it always seem to come down to form vs. function?) If you need, say, hot dipped galvanized square tubing for an infrastructure application, hot dip makes sense. If that steel tubing needs to look exceptional -- and doesn’t need to be exceptionally durable -- nobody will judge you for picking electrogalvanization.
If you want to look at other options, such as galvannealed steel, click here for a related blog post.