Zinc Chromate Plated Bolts

Whether a screw is galvanized or zinc plated it will feature a zinc shell.

Zinc chromate plated bolts.

The clear zinc bolts are required to remain rust free during a salt spray test. This is a secondary dipping process used on zinc or cadmium plated fasteners. Fasteners are used for fastening and securing materials such as wood metal plastic or concrete. When compared to steel for example zinc corrodes about 30 times more slowly.

They include nuts and bolts threaded rods structural bolts machine screws wedge anchors washers rivets and more in a variety of types and sizes including metric and inch. It increases corrosion resistance and can be colored. Standard clear chromate leave a bluish white hue. Therefore zinc serves as a protective barrier for screws.

Yellow plated bolts have to last 600 percent longer before red rust can appear during the same test. This additional layer passivates the zinc and protects it from white rust. Clear zinc bolts have a lower corrosion resistance according to fastenal. Well zinc can still corrode but it corrodes at a significantly slower rate than other metals and alloys.

For fasteners that need high corrosion or abrasion resistance a chromate conversion coating is applied over the zinc plating for additional resilience. As with cadmium this material is toxic and its use is decreasing. Anoop if you use the torque equation t kdp as explained on our torque page the friction coefficient for zinc plated bolts is 0 22 vs 0 25 for galvanized. If you plug in this value to the equation you will get torque values for zinc fasteners that are roughly 12 lower than galvanized fasteners to achieve the same tension.