The zinc coating of steel by hot dipping is confusingly known as galvanizing, although no use is made of electricity in the process. It provides a cheap and effective method of producing a good rust-resisting coating on steel sheet, steel wire and on miscellaneous fabricated steel and cast iron articles, such as tanks, vessels, hardware, pipes and fittings and structural components, most of which will be exposed to the weather, or to damp air or water. Galvanizing is carried out on a very large scale and, with perhaps the exception of paint, is the most widely used protective coating system. Thus in 1965 in the UK, out of the total consumption of 357,000 tons of zinc, a total of 92,052 tons (25%) was used for galvanizing, comprising sheet and strip 23,836 tons, wire 19,596 tons, tube 13,4333 tons, and general 35,187 tons.
The solution for zinc coating during galvanizing the parts are taken from the fluxing solution and well drained, or even dried off, without rinsing, and immersed into the clean molten zinc. They are then withdrawn as quickly as possible, and encouraged to drain by shaking of brushing, special attention being given to the lower edges. The parts are then put aside to cool or quenched in an air blast or in water. The thickness of the zinc coating can be controlled are usually expressed by the weight of zinc and the period of immersion. Coatings are usually expressed by the weight of zinc per unit area; 2 oz zinc per ft2 = 0.0018 in thickness is a usual coating, but thickness of 4 to 6 oz are possible. As a result of surface tension forces, small reentrant crevices and angles, such as screw threads, tend to become clogged, whilst the coating may be thinner than average on sharp edges, except at the bottom edge where may be a thickening.
The solution for zinc coating during galvanizing the parts are taken from the fluxing solution and well drained, or even dried off, without rinsing, and immersed into the clean molten zinc. They are then withdrawn as quickly as possible, and encouraged to drain by shaking of brushing, special attention being given to the lower edges. The parts are then put aside to cool or quenched in an air blast or in water. The thickness of the zinc coating can be controlled are usually expressed by the weight of zinc and the period of immersion. Coatings are usually expressed by the weight of zinc per unit area; 2 oz zinc per ft2 = 0.0018 in thickness is a usual coating, but thickness of 4 to 6 oz are possible. As a result of surface tension forces, small reentrant crevices and angles, such as screw threads, tend to become clogged, whilst the coating may be thinner than average on sharp edges, except at the bottom edge where may be a thickening.