Screws with zinc: everything you need to know

Screws with zinc are a standard option for construction projects. However, screws with zinc may be hot-dipped galvanized steel, electroplated, or mechanically plated. All options are feasible, trustworthy solutions for your projects, but what’s the difference between them, and when should you use each?

How do different zinc-coated screws vary?

Hot-dipped galvanized steel, zinc-plated, and mechanically plated screws are all coated in zinc but require different manufacturing processes. The coating method used will depend on the size and shape of the screw as well as its intended use.

Hot-dipped galvanized screws are soaked in molten zinc to create a coating approximately 1.0 mm thick. High strength fasteners are usually hot dipped in order to make sure that the strength isn't compromised by corrosion.

Meanwhile, zinc-plated screws are placed in a solution of water, saline, and zinc, then treated with an electrical current to form a coating about 0.2 mm thick. As a result, hot-dipped galvanized screws provide approximately five times as much protection from the elements as zinc-plated screws, but are less aesthetically pleasing. 

One key difference between electroplating and hot dipped galvanizing is the consistency of the zinc coating.  Electroplating is much more controllable from a thickness standpoint, which is better for even coverage of threaded fasteners. Meanwhile, hot dipped screws can have issues with too much coating in between the threads and other small features

Can zinc-coated screws rust?

Zinc corrodes about 30 times more slowly than steel, serving as a protective barrier for screws. That being said, zinc-coated screws are rust-resistant, not rust-proof. So be aware that zinc-coated screws will ultimately rust under the right outdoor conditions.

Over 99% of the fasteners SFS sells for exterior use are coated with VistaCoat on top of the zinc, ensuring these fasteners are safe for exterior use.

Hot-dipped galvanized screws are the most rust-resistant and, as a result, are best suited for outdoor applications. However, if rust is a significant concern, you should explore stainless fasteners instead. Stainless steel fasteners provide cost savings in the long run due to less failure and a longer lifetime of the building when used externally.

When should you use different zinc-coated screws?

The various types of zinc screws have differing uses. Zinc-plated screws are typically used for interior applications unless an additional coating is applied over the zinc plating. This is due to their tendency to rust under specific outdoor conditions. Additionally, zinc-plated screws have a shiny finish, making them more appealing for indoor use.

Meanwhile, hot-dipped galvanized screws are typically used for exterior applications and in structural attachments. It is codified in the international building code to use hot-dipped galvanized screws in this manner.

Optimize your use of zinc screws with SFS

Zinc-coated screws are an excellent option for many projects. However, depending on the conditions your fasteners will be exposed to, you must consider different types. Evaluate both the situational use of your screws and the desired aesthetics to determine which option is best for your project.

For examples of SFS screws that leverage the rust-resistance of zinc, we welcome you to check out the 1/4-14 ZAC® Type 17-AB and #17 ZAC® Type AB in our metal-to-metal self-tapping collection. Similarly, many of our clip screws are zinc-plated. 

Regardless of whether you choose SFS screws made with zinc, steel, or other alloys, expect nothing short of industry-leading quality standards. We consistently test, re-test, and innovate to ensure our fasteners redefine the limits of strength, corrosion resistance, and efficiency. 

Have additional questions about when to use various screws with zinc?
Members of the SFS team are ready to help. Call 610-376-5751 to consult with a specialist. Alternatively, if you’re curious about other metals frequently used in commercial fasteners, read 300 vs. 400 stainless steel (including 410 vs. 304) or 304 vs. 316 stainless steel screws.