New Zealand Steel

Is as much the story of the ‘black sands’ of the west coast of New Zealand’s North Island. First noted by Captain James Cook in 1769, these ironsand deposits were long recognised as a rich reserve of metal ore.


The ironsand (titanomagnetite) was formed through the breakdown of rocks originating from volcanic activity in Taranaki 2.5 million years ago. Over time, the heavy, dark sands were transported by ocean currents and deposited on beaches, forming dunes of up to 90 metres high. Early European settlers to the west coast were intrigued by the sands’ magnetic qualities. But experiments to smelt the iron from the ironsand met with little success.

It wasn’t until the 1950s, with both the local economy and steel demand growing, that serious consideration was given to utilising this valuable resource in a home grown steel industry. At about the same time, new technologies were evolving overseas that made possible the use of ironsand in steelmaking.
So in 1959, the government established the New Zealand Steel Investigating Company to determine the technical and economic feasibility of manufacturing steel from indigenous raw materials.
The Birth of New Zealand Steel

New Zealand Steel Limited was incorporated in 1965. The long-term vision of those behind it was to establish a steel industry that would utilise the abundant local raw materials.
In 1966, construction started on a mill at Glenbrook, 65 kilometres south east of Auckland. Commercial operations began in 1968, with imported feed coil being used to produce GALVSTEEL™ steel for domestic and Pacific Island markets.
Meantime, the company had been pioneering the direct reduction process for reducing iron oxide (ironsand) into metallic iron. This culminated in the commissioning in 1970 of iron and steelmaking facilities to produce billets for domestic and export markets.
Expansion continued with the commissioning of a pipe plant in 1972 and a COLORSTEEL® prepainting line in 1982. Total output at this time averaged 300,000 tonnes a year.


Major investment in the 1980s saw the commissioning of continuous slab-casting facilities and both Hot and Cold Strip mills. By 1987, New Zealand Steel was operating as a fully integrated steelworks, producing flat steel products made solely from New Zealand Steel feed stock.
The existing continuous galvanising line was modified in 1994 to produce ZINCALUME® steel, in addition to traditionally hot dipped galvanised products.
Today, the rich ‘black sands’ of the North Island continue to underpin steelmaking at Glenbrook.

Two products produced by New Zealand Steel are Colorsteel® and Zincalume®, are probably the most commonly used roofing products in NZ.


COLORSTEEL® Endura™ and COLORSTEEL® Maxx™ prepainted steel continue the tradition of a great roofing product, with a range of colours to suit every New Zealand home. These two new products have been designed to meet the demands of New Zealand’s range of environments.

The COLORSTEEL® Endura™ prepainted steel range has 24 nature inspired colours – from the dramatic to the subtle. The range of colours will allow your designer to either blend with the local surroundings or use colour to enhance bold design.

The COLORSTEEL® Maxx™ prepainted steel range has been designed for use near the coast, with 18 designer colours to blend with the local environs.

The roof is an integral part of every building. Product selection is an important consideration; the colour of the roof may be used to contrast (or complement) the rest of the house. COLORSTEEL® prepainted steel roofing is suitable for almost every design, long straight lines or gentle curves, which can be used to create stunning homes. Steel’s light weight gives greater design flexibility, while the colours give the designer the choice of blending or creating interest through building design.

COLORSTEEL® prepainted steel products are used extensively in building applications: roofs, fascias, gutters and cladding. Only New Zealand Steel manufactures COLORSTEEL® prepainted steel. Other products may look the same, but they don’t always match the performance of the genuine COLORSTEEL® prepainted steel.


New Zealand Steel Limited introduced ZINCALUME®, zinc/aluminium alloy coated steel, to the New Zealand market in 1994. ZINCALUME® coated steel represents a significant improvement on the traditional zinc coated galvanised steel. Since its introduction, ZINCALUME® coated steel has been widely accepted and has the major share of the steel building products market.

The ZINCALUME® coated steel has been formulated to give a significantly longer service life than a galvanised coating. This is of particular value in New Zealand where the prevailing winds carry corrosive salt laden air many kilometres inland.

The ZINCALUME® steel coating combines the corrosion protection of aluminium with the sacrificial protection of zinc, giving the advantages of both metals. The resulting alloy coating enhances corrosion resistance, making it ideal for such applications as roofing and cladding.

ZINCALUME® coated steel is produced by a continuous hot dip process similar to that used to manufacture galvanised steel. While both ZINCALUME® steel and galvanised steel products have a steel base, galvanised steel has a coating of 100% zinc, whereas ZINCALUME® coated steel has an alloy coating of 43.5% zinc, 55% aluminium and 1.5% silicon. ZINCALUME® coated steel conforms to AS1397:2001.

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