TIMBER EXPERT.

Press, Volume LVIII, Issue 17452, 12 May 1922, Page 8

TIMBER EXPERT.

VISIT OF MR H. D. TIEMANN.

THE DRY B3MT METHOD,

Mr Harry D. Tiemann, Master of Engineer,- Master of Forestry, and dry kiln expert .for the United States of -America, who is at present visiting New Zealand by invitation of the Forestry Department and the New Zealand Sawmillers' Federation, arrived in Christchurch yesterday, and in the evening met a number of local business people interested in the production and use'of 'timber. Mr Tiemann is regarded as ; the world's greatest expert on the subject of timber season-: ing, and brought into' operation a 8 B e * cial kiln for this work, known as tne "Tiemann Kiln." Mr Tiemann said last evening that the commercial value of timber depended on the efficiency of the seasoning it received. Where timber was to be used permanently in a warm temperature as m a well-heated house, such timber re-, quired to be seasoned to a greater extent than was possible by the open air method of seasoning. Kun-oryint would be essential to prepare the timber for the use to which it was to b put. An approximate cost of Kiln-ary-lßß aJr \gM atrsft the timber in a more uniform condition. For the finest grades of work, kiln-drying was essential even -if the timjoer had been air-dried betoie. Another advantage was that with the kiln-drying ■ method . was possible to fulfil an order at short notice. .Kilndrying also wou'.d. properly sterilise the wood as'against insect pests. The process of kiln-drying was no more an artificial method than air-drying. The difference was that with the kiln method there was complete control or the conditions, whereas with air-drying ;here was no such control. The prejudice against kiln-drying arose from a lack of knowledge of what kiln-drying signified, and also as a result of the poor processes employed. Different kinds of timber required different lengths of time for kiln-drying. An oak board would require 40 days to dry in the kiln from the green, whereas a piece of Douglas fir would take only 24 hours. There was an advantage m leaving dry-kilned timber out in the open—in a protected shed —for two weeks after it left the kiln, and before it was used, although if the process was properly followed there was no real necessity for such additional air-dry-ing. Lumber .required certain conditions for the best drying, and dry kiln was intended to produoe those conditions. If the atmospheric conditions could be controlled that would be the same as using a dry kiln. The three factors under control in a dry kiln were: —(1). The circulation of the air ; (2) the humidity of the air; and (3) the temperature, of the air, the importance of those, factors being according to the order given. ■ . , .L Mr Tiemann then'explamed at length the different methods adopted in producing tho dry kiln process, also the operating methods in the practical working of the kiln. In reply to a question, Mr Tiemann said that lack of knowledge on the. part of the operators' was responsible for bad conditioned timber kiln-dried. Poorly driod kiln timber, he added, was. always •worse - than ■ air-dried * ■timber. It wis preferable that' the timber should be kiln-dned direct from the saw-mill, but that was not always possible. The better plan then would be to stack the timber,. and. air-day it until the free ■water was removed. The hydroscopic moisture would then be removed in the. ! kiln-dtyingi - ■ - - - ' ■ - . ; To-day Mr Tiemann will give- a demonstration at Mr C. E. Otley's dry kiln, and he will leave for Wellingtou to-night.

, TIMBER SEASONING.

Mfi TIEMANN'S VIEWS.

During a chat with a "Wellington reporter, Mr Tiemann said he had been visiting Australia at the instigation of the Victorian Forest Commission,. who had retained his services from the United States Government for the purpose of obtaining his advice in regard of the kiln-drying, or seasoning, of. native timbers. • He has been in Victoria. for six months, and in West Australia about a month, lie has been giving lectures and conducting experiments of an extensive and varied ciiaracter in the drying kilns, Ihe length iof time taken for seasoning not only depends upon tiie nature of the. timbers, but. also the suitability of tne kiln. Australian woods are hard, and take longer either by the air or kilni processes. About thirty days is the aver-, age seasoning time in kilns for Ijin lumberbut some will take six weeks, while Oregon pine can be seasoned in twenty-four hours. Whsther New Zealand pines can be dried in anything like a month remains to be seen, as it is not yet known if they will stand the high temperature of the kilns, but it iB anticipated that some of the Dominion timbers will respond to correct kiln processes in three weeks.

Kiln-drying is the application of scientific principles to the seasoning Of lumber.

Mr Tiemann was met by the director of the Forest Service, Mr Ellis, and the engineer in forest products, Mr Entrican, and the- latter gentleman stated that kiln-drying in New Zealand had not up to now been as successful as had been hoped. Mr Tiemann would, in the course of his visit, . inspect several of the kilns and give advice as to their proper management, pointing out where errors had been made Mr Tiemann remarked that he'would be specially interested in totara, kauri, rimu, and white pine, and he ■would also investigate the matai,' or black pine. The object of kiln-drying was not, perhaps, so much, to shorten the time of Seasoning as to ensure that the timber was properly seasoned. Unless it is done properly, great losses are likely « ccur through cracking, honeycombing, and warping, resulting in imperfections after the article has been manufactured.

Such were especially likely to occur, in hard woods if the seasoning S' 1 "* especially in such J*tides as tables, cupboards, desks and household furniture. ' ana The protection of. Australian forests against destruction, especially by fire was a point which had interested him ..abided Mr Tiemann. The tendeßcy , n a-new country is to discbunt drtuture. values for immediate interre?ult that n <> attention' is paid to the value of the timber land as a national aeset, and this valuable material is frequently allowed to be Sl2&.T* * a +li reS b€en J lighted indiscrimin+!fi r i?° uu n of acres of noble trees, .almost priceless timber, have been reduced to ashes. It is" tiie duty of.the Government to care for the future interests of the country, and it is essential that the present forest lands, .or a considerable portion of them, should be preserved. The destruction is not so much a question of present value of the wood destroyed as of

(Continued at foot of next column,j

the future value of the land for the permanent production of timber. Mr Tiemann agreed that America had greatly depleted her timber resources, and where she once exported wood pulp, ..she now imports two-thirds of that supply from, Canada. America, was far ahead of Australia, however, in forest fire prevention, although in the past she had lost 81 million acres of timber through fires and careless use.