What coatings do there exist on fasteners?

Sharardization:  (see our Auto-Lok Nuts) Sherardizing is a lasting, anti-corrosive, temperature and wear resistant layer which is applied uniformly over the entire surface of the fastener.Sherardizing produces an ideal surface for other processes such as rubber to metal bonding and the application of organic oils, stains, lubricants and sealants and provides a cost effective, high performance alternative to hot dip galvanizing. Anodization Anodizing is an electrolytic passivation process used to increase the thickness of the natural oxide layer on the surface of  the fastener. Anodising increases corrosion resistance and wear resistance and provides better adhesion for paint primers. Anodising changes the microscopic texture of the surface and changes the crystal structure of the fastener near the surface. Thick coatings are normally porous, a sealing process is often needed to achieve corrosion resistance. Anodised aluminium surfaces are harder than aluminium but have low to moderate wear resistance that can be improved with increasing thickness or by applying sealers. Zinc Flake coated (see some of our camloc fastener receptacles) Zinc Flake Coating is a generic term for the coatings consisting predominantly of Zinc Flakes usually with a small quantity of Aluminium. The flakes are about 1µm thick and are bonded together with inorganic or organic compounds. The coatings come under brand names such as Geomet® and Dacromet® and are used extensively by the Automobile Industry to give salt spray resistances exceeding 600 hours with a thin coating, making them ideal for fasteners. This coating does not induce Hydrogen Embrittlement, which means that high tensile fasteners can be safely coated.   Galvanised coating (typically not for our products) Fasteners hot dip galvanized at high temperature take on a uniform, matt grey.The initial cost of hot dip galvanizing threaded fasteners is generally a little higher than zinc plating  the cost per year of rust-free life prove that hot dip galvanizing is by far the most economical coating. High strength bolts up to grade 8.8 can be galvanized without difficulty. Grade 10.9 bolts may require blast-cleaning as an alternative treatment prior to hot dip galvanizing and there may be some tempering back.