Q. What are different types of fastener finish. What is importance of each finish?
Answer: The following are the five most popular types of coatings for fasteners that may meet your requirements:
Clear Zinc: This is one of the most popular fastener coatings available in the market. Inexpensiveness is one of the main reasons for their immense popularity. The clear zinc coated fasteners can withstand oxidative damage. Thus, the clear zinc coatings are recommended for conditions, where they are exposed to high humidity, and stand a high risk of rusting.
Yellow Zinc: The yellow zinc coating is applied electrically to the fasteners. These coatings are ideal for conditions where the fasteners may come in contact with water or other liquids. The yellow zinc coating is also ideal for humid conditions. These coatings need to be applied precisely to inhibit corrosion.
Gray Phosphate: This is another important fastener coating which is designed to improve the lifespan of fasteners. However, this type of coating is not recommended for conditions where there is a high risk of corrosion. For example: gray phosphate coated fasteners are not ideal to use in marine applications. This means they should only be used in dry settings such as vehicles or interiors of buildings, etc.
Hot Dip Galvanized: Also, referred to as HD, this coating is applied on steel to protect it from corrosion. The hot dip galvanized fasteners are coated with zinc. These fasteners are generally considered for outdoor applications where they will be exposed to extreme weather conditions such as snow, heat, and rain. The HD fasteners are also ideal for coastal areas where the salt content is higher.
Electro Galvanized (EG): These fasteners have a thin layer of zinc coating which offers frugal corrosion protection. The EG fasteners are used in areas where less corrosion protection is needed such as kitchens, bathrooms, or other areas that are susceptible to humidity or moisture. Most fasteners used in roofing are electro galvanized and are replaced before the fastener starts wearing.
There are many other coatings but only few popular are discussed here.