The New Zealand Railways Magazine, Volume 4, Issue 10 (February 1, 1930)
The Department's Latest Enterprise
The Department's Latest Enterprise
Kiln-drying timber plant is to be installed at the Otahuhu (North Island) and Addington (South Island) railway workshops, at a total cost of about £20,000, for treatment of departmental supplies of New Zealand timber. The plant will be capable readily of extension to treat timber for other departments.
In making this announcement, the Minister of Railways (Hon. W. B. Taverner) said that the Department was convinced that it would benefit by securing better conditioned, more lasting timber for its constructional work. By cheaper, as well as more effective conditioning, kiln-drying would allow indigenous timber to replace a great deal of imported timber, and would render useful for constructional purposes a considerable amount of sap wood and non-heart grades, that would emerge as an inferior product from the old seasoning process of air-drying.
Greater Use of Local Timber.
It was well known that the New Zealand timber industry in its attempts to secure higher utilisation of the tree, and, therefore, better economies, had in some cases found a difficult problem in the comparatively small percentage of heart. Any conditioning process that would secure higher results from non-heart timber, the profitable disposal of which had been a longstanding trouble with sawmillers, would therefore be of vital help to the industry, and he hoped the two kilns would become of national importance, in that they would provide the constructional shops of the Railway Department with better timber at less seasoning cost, make available for them a greater proportion of New Zealand timber, and inspire the timber industry and all wood users with the idea of higher utilisation and greater economy through the medium of artificial drying.
Evidence of the success of kiln-drying abroad was complete. The evidence of its success as applied to New Zealand timbers was not as complete as it might be. He hoped that that would no longer be the case when the Railway Department's kiln-drying was in full operation. He wished to emphasise that in this enterprise the Department had the valuable co-operation of the Department of Forestry.
“Kiln-drying,” continued the Minister, “will enable a direct financial economy to be effected. Substantial though this saving is, the better service, the longer life, and lower maintenance cost that may be expected from vehicles constructed with kiln-dried timber is far more important. Compared with air-dried timber, economy will be effected in the milling process in the workshops, because with the kiln-dried article there will be less warping and shrinkage. A more regular product will be treated in the workshops, and loss due to handling and milling timber that afterwards proves serviceable will be cut out.
Less Foreign Timber.
“An approximate analysis of the two million feet to be used annually at the Otahuhu workshops indicates that without kilns it will include 350,000 feet of imported hardwoods. With kilns that figure will fall to 100,000 feet. Without kilns the requirement of scarce and costly kauri will be 500,000 feet, and rimu 600,000 feet, but with the kilns kauri can be reduced to 100,000 feet, while rimu will be increased to 1,000,000 feet. As rimu is the timber in principal production in New Zealand, and a timber intimately wrapped up with the non-heart problem, these figures are very informative, and will, I think, be widely noticed and appreciated.
“Continuing the comparison, the use of kilns will, it is estimated, increase the use of totara from 150,000 feet to 200,000 feet, increase matai from 100,000 to 200,000 feet, and will reduce the quantity of imported timber to a corresponding extent, as kiln-drying should make not only for greater utilisation of the non-heart portion of the tree, but also the greater utilisation on the varieties of trees in a native forest. Some New Zealand timbers are not suitable for the Railway Department's purposes when air-seasoned, but become so when kiln-dried.
Air-Drying and Pests.
“Coming to the point of salvage of non-heart timbers, it has to be borne in mind that the time taken by air-seasoning relative to kiln-drying not only means money, but means also greater risk to such timbers from exposure, because sapwoods are susceptible to the attack of pests while being air-seasoned. It is expected that kiln-drying will altogether overcome that difficulty, and will provide a sufficiency of the standard finished product, while reducing timber stocks and storage space required for air-seasoning, and will be both better and cheaper for the Department, besides assisting an important New Zealand industry.”