What is the difference between galvanising and powder coating?

Galvanising is corrosion protection: zinc metallurgically bonded to the steel, inside and out. Powder coating is a hard coloured finish baked on top. One stops rust, the other decides the colour and protects the zinc from going dull.

For anything outdoors that you want to forget about, yes. Powder coat alone on bare steel looks identical on day one and fails from every chip and drilled hole. Galvanising underneath means a chip is cosmetic rather than the start of a problem.

Can existing gates be galvanised?

An existing item can sometimes be stripped and dipped, but it has to be sound and free of filler and old paint first. Whether that is worth doing against replacement depends on the item, and we will give you an honest view.

What colours can I have?

Any standard powder coat colour. Black, anthracite and dark green are the most requested for domestic railings and gates, with matching colours picked up from existing ironwork where there is some.

Will powder coating chip?

It can, like any hard finish, usually from an impact rather than weather. On galvanised steel a chip is a cosmetic touch in, which is why the order of the two processes matters so much.

How long does the finish last?

A properly galvanised and powder coated gate or railing run will go decades outdoors with nothing more than washing. That is the whole argument for steel over painted ironwork on a boundary you do not want to think about again.

Metal Fencing and Gates

Galvanising and Powder Coating Explained

Why the finish decides how long steel work lasts, and what to check on any quote you are given.

Two identical looking gates can be twenty years apart in service life, and the difference is almost never the steel. It is what was done to it after it was welded.

There are three finishes you will be quoted. Painted bare steel, which looks right for a year. Powder coating straight onto bare steel, which looks right for several. And hot dip galvanising followed by powder coating, which is the one that is still sound when the house changes hands.

This page explains what each one actually does so you can read a quote properly, whoever you end up buying from.

The numbers that matter

Hot dip galvanising: The fabricated item is dipped in molten zinc, which bonds to the steel inside and out, including inside hollow sections
Powder coating: A dry polyester powder applied electrostatically and baked, giving colour and a hard surface
Correct order: Galvanise first, then coat. Coating over bare steel leaves nothing protecting the metal once the coat is chipped
Weak points: Site drilled holes and site cuts, which is why any adjustment on site is treated before handover
Maintenance: A wash. No annual repainting, unlike wrought iron finished in paint alone

If a quote says powder coated and does not mention galvanising, ask the question. The answer tells you what you are actually buying, and it explains most of the price difference between two quotes for the same gate.

What it suits

Any steel that will live outdoors in a British winter
Gates and railings within reach of road salt or a busy junction
Side returns, light wells and anywhere that stays damp and unventilated
Coastal or exposed sites, and anywhere replacement means digging up a drive

There is one honest exception. On a restoration where the client wants traditional painted wrought iron and is happy to maintain it, paint is a legitimate choice. It is a maintenance commitment, not a shortcut, and it should be a decision rather than a surprise.

Galvanising and Powder Coating Explained by Capital Fencing Ltd (1)

Galvanising and Powder Coating Explained by Capital Fencing Ltd (2)

Galvanising and Powder Coating Explained by Capital Fencing Ltd (3)

How the job runs

1. Fabricate first
Everything is welded, drilled and finished before it goes anywhere near the zinc, because dipping a completed item protects the welds and the drilled holes too.
2. Galvanise
Hot dip galvanising coats inside and out, including the inside of hollow posts and rails, which is exactly where rust starts on a painted gate.
3. Coat and cure
Powder applied and oven cured for a hard, even colour that does not need annual attention.

Questions we get asked

What is the difference between galvanising and powder coating?: Galvanising is corrosion protection: zinc metallurgically bonded to the steel, inside and out. Powder coating is a hard coloured finish baked on top. One stops rust, the other decides the colour and protects the zinc from going dull.
Do I need both?: For anything outdoors that you want to forget about, yes. Powder coat alone on bare steel looks identical on day one and fails from every chip and drilled hole. Galvanising underneath means a chip is cosmetic rather than the start of a problem.
Can existing gates be galvanised?: An existing item can sometimes be stripped and dipped, but it has to be sound and free of filler and old paint first. Whether that is worth doing against replacement depends on the item, and we will give you an honest view.
What colours can I have?: Any standard powder coat colour. Black, anthracite and dark green are the most requested for domestic railings and gates, with matching colours picked up from existing ironwork where there is some.
Will powder coating chip?: It can, like any hard finish, usually from an impact rather than weather. On galvanised steel a chip is a cosmetic touch in, which is why the order of the two processes matters so much.
How long does the finish last?: A properly galvanised and powder coated gate or railing run will go decades outdoors with nothing more than washing. That is the whole argument for steel over painted ironwork on a boundary you do not want to think about again.

Ask what is under the colour

On any metalwork quote, ours or anybody else's, ask whether the steel is galvanised before coating. Call 07885907880 and we will happily talk through a quote you have been given elsewhere.

Related metal work: Vertical bar fencing, Side and pedestrian gates, Palisade fencing. Main hub: metal fencing and gates.

By town: Barnet, Enfield, Hertford, Watford, St Albans, Hatfield, Welwyn Garden City, Stevenage.