Fasteners are often produced in a range of coating options. Coating affects the durability and cosmetic finish of a product. Below is a brief run through of the options available from us.
Black in colour, they are generally used on nuts, washers, screws and bolts that are most likely to be welded
The process that involves an electrolytic application of zinc to metal. This produces oxidation of the protected metal, and the zinc coating acts as a barrier to corrosion.
Bright Zinc Plated
The most common, silver looking, and provides effective corrosion protection on steel fasteners.
A zinc plating is applied with a black passivate on steel fasteners to provide corrosion resistance and a cosmetic look for applications of the same colour. There are a number of zinc alloy processes that are available; zinc-iron, zinc-cobalt, zinc-nickel, zinc-tin alloy.
Zinc Yellow Passivate (ZYP)
This coating is achieved using the same method as Zinc Black but with different alloys to achieve a particular cosmetic look.
Highly corrosion resistant and is electrically conductive. Primarily copper and zinc alloy. Generally available in most metric and imperial sizes. Be warned – the price can be volatile!
Similar to bright zinc but slightly more of a yellow tint and very shiny and smooth. Very hard wearing and durable. Mostly used on machine screws.
Dark grey plating for steel parts for corrosion resistance and lubricity.
Old style plating which offers protection from corrosion and resists the growth of mould and bacteria. No longer commonly used.
A2 Stainless Steel
Most common stainless steel A2(304). Offers excellent corrosion resistance for most applications. Widely available in metric and imperial.
A4 Stainless Steel
Marine grade A4(316). Offers increased resistance to chloride corrosion compared to A2(304). Widely available in metric sizes and can be sourced in imperial threads.
A4-80 Stainless Steel
The same as A4 but a higher grade. Only available in metric sizes.
Similar process as Zinc plating but a thicker layer is applied. Has a higher corrosive resistance than zinc. Commonly used in agriculture and marine industries.