We’ve talked regularly in this space about the galvanizing process for steel, one that involves coating metal with a thin layer of zinc to help protect it from the environment and the risk of corrosion. There are several different galvanizing formats possible, and also several possible issues that may arise during these various processes.
At Wasatch Steel, our steel services include helping you process our steel materials in any way you require – and assisting with any possible issues that come up. One such issue during certain galvanizing processes is known as “white rust,” which is an actual layer of rust formed by the zinc that’s supposed to be protecting you from that kind of corrosion. What is white rust, how does it affect steel projects, and how can you prevent it during the galvanizing process?
White rust is so named due to its white, chalky nature. It’s created when zinc, which is used to coat various forms of metal, is exposed to hydrogen and oxygen, leading to the formation of zinc hydroxide.
If you’re familiar with rust and corrosion, this term may sound familiar – it’s not far off from iron oxide, which is perhaps the most common form of rust out there. The difference here, though, is that zinc hydroxide can only form on zinc or zinc-coated materials.
As we noted, white rust forms after an interaction between zinc and hydrogen plus oxygen. The most common occurrence here is when newly galvanized metal comes into contact with water or hydrogen dioxide – white rust is most likely to form directly after the galvanizing process has taken place, as the zinc coating is still forming into stable oxides and has not finished this process completely.
It’s also common to see white rust when storing galvanized sheet metal. Moisture or condensation can often become trapped between single sheets here, creating the interaction that forms white rust. When storing recently galvanized steel sheet, be sure to remove all possibility of moisture to avoid white rust.
There are a few simple steps to take to ensure you won’t deal with white rust when galvanizing steel:
For more on avoiding white rust after galvanizing steel, or to learn about any of our custom steel products or services, speak to the pros at Wasatch Steel today.