Hot Dip Galvanizing of Architectural/Smooth Finish Steelwork


Hot Dip Galvanizing of Architectural/Smooth Finish Steelwork

Hot Dip Galvanizing (HDG) is the preferred first choice for steel treatment due to its maintenance-free and durable finish, which provides outstanding corrosion protection, predictable performance and a long lifespan. While the positives of HDG heavily outweigh the negatives, there is one use-case where HDG is not recommended – Architectural/Smooth Finish Steelwork.

HDG is a protective treatment process where steel members are immersed in a bath of molten zinc. The molten zinc and steel react to form a series of zinc-iron alloy layers, with the coating thickness attributed to the mass of the steel being galvanized. The steel is also immersed in degreasers, acid, water and other solutions throughout the process, as required. For a video walkthrough of the galvanizing process, please click HERE.

The primary purpose of HDG is to provide corrosion protection to the steel, and this is the basis of its use in construction. When it comes to the finish of HDG steel members, steel composition, cooling rate, bath chemistry all affect the appearance of galvanizing, along with any variation in the HDG process. Ash and Dross is also formed during the process, which can cause bumps/lumps in the finish of the HDG steel.

HDG is a complicated and irregular procedure, with many variables along the process, depending on the type, size and shape of the steel members. Unfortunately the finish of HDG cannot be controlled to the required extent, and as such is not suitable for use in architectural steelwork unless excessive preparation work is completed by your painter. Epoxy/Duplex Coated steel is also affected as it is sprayed over the top of whip blasted HDG steel.

When it comes to architectural steelwork, we recommend discussing your steel needs with your engineer to determine suitable treatments that will provide both the corrosion protection and desired finish. As always, Metwest Steel is willing and ready to assist in these discussions to provide input on practicality and pricing.

Yours sincerely,

Ryan Gillam
General Manager