STEEL SASH

Evening Star, Issue 19843, 17 April 1928, Page 2

STEEL SASH

VALUE OF METAL SPRAYING GUARANTEE AGAINST RUST A reprint article of American origin, which extolled wood sasli in respect to a comparison with that of the steel variety, appeared in this column a fortnight ago. It has elicited the following response from a contributor : “An article has recently appeared in your columns condemning the steel sash. In view of the growing demand and extensive use of this product in New Zealand, it seems only right that something should be said in its favor. “The growth of this industry is indicated by the fact that since its commencement in New Zealand some sixteen years ago there are now no loss than' five companies _ producing steel windows in the dominion. The advancement of building construction has found the steel cash a necessity, due to its superiority over the wood sasli, and it can now be seen in all our modern buildings, schools, offices, and in the hotter-class brick residential property. And here we can name, as of local interest, such buildings as the Medical School, ‘Evening Star,’ ‘ Times,’ Public Trust, Queen’s, and our new Town Hall.

“ In comparison with the wood sash it can be said that the steel sash is everlasting, strong, durable, and impervious to attacks from vermin or atmospheric conditions. “Made of British rolled mild steel sections, their strength is undoubted; at the same time the heavy frames, mullion, and transom bars necessary in the wood sash are dispensed with in the steel, thus giving maximum ventilation and daylight from the window opening. “Steel sashes are made, to any design, however ornamental, and to sizes required by the architects. The opening portions can also be made to open in or out, hung at side, top, bottom, vertically or horizontally pivoted. Thus an architect finds an extensive range of types and sizes from which to choose. “ Furthermore, the sloel sash is constructed so that the glass can bo cleaned from the inside; this is essential in our modern many-storied building, and a boon to a housewife in a private residence. The alternating seasons, heat, and moisture have a damaging effect on the wood sash. Jn the winter wo find our wood sash requires planning to allow It to operate easily; with the next summer heat the wood dries and shrinks, and we are constantly annoyed by its rattling. Such annoyance does not exist with the steel sash, as the change of” temperature is not sufficient to affect the metal“lt is said that steel window frames will rust; so will any thing else made of steel rust unless it is properly cared for. This problem of oxidisation due to atmospheric conditions has been a ticklish one for manufacturers for some years. Happily it can now be said that rust can be definitely prevented, and this is done by what is known as the ‘ Sclioop 1 process of metal spraying. This process is new to New Zealand, and we think merits some explanation here. “The surface of the steel is primarily sandblasted to remove all scale and impurities from its surface. On to this surface any non-ferrous metal can then bo sprayed, zinc being used, as an anti-corrosive. The zinc is applied by what is known as the ‘pistol.’ This ‘ pistol ’ consists of a small aluminium box with a nozzle on the front side. The zinc is fed into the roar of the pistol in the form of wire by a. small air turbine contained in the pistol. To the underside of the pistol arc attached three tubes—one air line, one oxygen, and one coal gas. The compressed air drives the turbine, whilst the oxygen and coal gas unite, in’ the nozzle, which is lit at the forward end. The oxygen and compressed coal gas burning atomises the zinc wire and j forces it through the nozzle in the form of a spray, which readily adheres to the surface to which it is directed.

“ Coming from the sandblast room the steel has a roughened matt surface, and to this the zinc is immediately applied. So small arc these particles of zinc meeting the roughened surface of the steel that the two metals may be almost said to alloy with one another at this point. This application is not done until the steel sash is completely fabricated, so that it is then hermetically sealed against all weather conditions. Thus can steel sashes be guaranteed against rusting. “This process of metal spraying is carried out in Dunedin, and apart from the local buildings mentioned above it is interesting to note that the steel sashes supplied to the N.Z-11. new workshops at Hillside and Addington by the firm have also been zinc coated. The process of metal spraying is by no means confined to the steel sash, as it is used m connection with all structural work, such as bridges, tanks, etc. In the steel sash industry it is largely used in England and Australia, and as, with the advancement of building construction during this century, the wood structure has been replaced by the steel and concrete type, so must the steel sash supersede that made of wood.”