Apart from the protective coatings mentioned above the fasteners are protected by black paint, and zinc phosphate coating and natural coating are also provided according to customer requirements with a thin layer of protective oil to protect against rust.
Black heat treatment is done by cooling the parts to be blackened by heat in the water-oil mixture at an appropriate and soluble temperature, and to protect it with rust, we use protective oil.
Zinc phosphate coating is a chemical transfer coating of steel surface to keep it from rust preventive oil and provide good corrosion resistance. The paint will be about 10-20 g per square meter, and it will be gray to black. It will provide temporary protection for approximately 48 hours from the natural salt spray.