What Is Galvanising and Why Is It Done to Steel Doors?

When looking for steel doors for your business or your home, you’ve probably noticed that many of them are galvanised. What does that mean and why is it important? Galvanising is named for an Italian scientist from the seventeenth century who invented a process for bonding metals with the use of electricity. Now, most steel doors and other steel applications are galvanised through a process called “hot dip galvanisation.” It is popular because it is quick and very effective.

Hot Dip Galvanising

In hot dip galvanising, zinc is heated to about 450 degrees Celsius. The zinc is molten by the time it reaches this temperature. The steel items are then dipped into the liquid zinc, which binds to the outside of the steel. When the steel is lifted out of the zinc bath, the zinc is exposed to the air. In its excited state, the zinc readily transforms into zinc oxide. This eventually cools and hardens, creating a coating over the steel. At this point, the steel has been galvanised. Galvanising is a great option if you don’t want to purchase more expensive stainless steel.

Zinc as a coating protects the underlying steel from rust or corrosion, even in harsh weather conditions. Properly galvanised roller shutter doors can last for decades. In an inland area away from saltwater, a galvanised steel door can last for over one hundred years without rusting. In addition to the coating creating physical protection from rust, zinc also protects by being a sacrificial anode.

A Sacrificial Anode

When the zinc coating on your steel doors is scratched, you don’t need to panic. You can help protect the coating by painting the door or by applying some kind of oil to the scratched portion. The oil will drive out water and prevent it from rusting or corroding. The galvanised zinc portions will continue to work, even if there are scratches and the underlying steel is exposed. The steel will not corrode because zinc is a sacrificial anode. This means that zinc is charged differently than the underlying steel on an atomic level. Since it is charged differently, it is actually easier to corrode than the steel. Therefore, as corrosion and rust attempt to take hold, the zinc will corrode but the steel will not.

Weather Protection

A shutter door needs to remain stable and reliable for decades. It can keep your house or your business secure from bad actors as well as bad weather. Bad weather can adversely affect your business in ways that are often worse than the effects of criminals. A galvanised door will prevent that from happening. It needs to be galvanised because a rusty door will not open or close properly. Also, rusty metal becomes fairly weak and can be easily broken. If a door can be broken open or if it fails to close completely, it will not offer the type of protection you need.

Look for good quality shutter doors that are made for harsh weather. They will come from a reliable manufacturer who protects their doors with the latest galvanising techniques in order to help keep you safe.

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