NEWSPRINT MANUFACTURE.

Otago Witness, Issue 3882, 7 August 1928, Page 17

NEWSPRINT MANUFACTURE.

NEW ZEALAND WOODS.

ENCOURAGING EXPERIMENTS

The pulp and paper tests upon New Zealand woods, recently supervised in North America by Mr A. R. Entrican, engineer of the New Zealand State Forest Service, consisted of two separate studies, one a laboratory study and the other a commercial pulp and paper mill trial. The Government received a report upon the laboratory study some months ago, but withheld it from publication, since some of the conclusions were likely to be considerably modified by the results of the commercial mill trials. With the re ceipt this week of a report upon the pulp and paper mills trials, the Government finds its action in this regard justified and Mr Entrican is now engaged in modifying and . combining the results of the two studies, so that the complete report upon the work should be ready in about three weeks’ time. In terms, however, of the agreement entered into with the Government of the United States, which undertook the work, it will be necessary to submit to their Forest Products Labora tory, at Madison, the re-written report for approval. This is expected to d day the actual publication of the report until the end of September. In the meantime, the following statement, summarising the results and outstanding features oi the work, is issued for public information. SUMMARISING RESULTS.

The reports show that commercial grades of newsprint may be produced from insignis pine and tawa, and of kraft papers (i.e., wrappings, etc.), from rimu, insignis pine, and a number of other woods. Other classes of paper, such as book, fine printings, etc., may also be manufactured from some of these woods, but, since they are consumed in comparatively small quantities, they do not command the same attention as do newsprints and wrappings, which lead all papers in quantities used. PURPOSE OF TESTS.

It is not enough to know' how to grow trees; it is just as necessary “to know how to use them. Thirty years ago the Government initiated a tree planting programme which has gained momentum steadily, until to-day the Forest Service has planted some 136,000 acres, and expects to establish, this 1928 planting Beason, a further 63,000 acres. The Forest Service is administering, too, a forest domain of over 7,000,000 acres. All these plantations are yielding large volumes of wood, for which it is necessary to develop profitable markets. Some of the forest crop goes into building and constructional timber, some into poles and fencing posts and some into fuel wood. Yet there still remains material in the shape either of woods and mill waste, or of unused species, or of thinnings and improvement cuttings for which no outlet has appeared available largely because we did not know how or for what purpose to use them. intensive study of the situation in dicated that the most promising avenue tor the utilisation of much of the material - r? *'“ e P u P and paper industry, and Government decided accordingly that it should first ascertain if the principal woods were suitable for this purpose. Howto carry out the work was the first prob- ™ aJternatives presented theme ves: That of building a laboratory in New Zealand, or, alternatively, of arran"ing tor a recognised and established w™ r ? to n y ai ?F oad to undertake the work. Eventually, the second alternative was adopted. Not only did it promise to n® o B , ever A l times more economical; this of a local estabe"t would be high, and the developoperational technique very Uh^’t but the results from a recognised would be more readily acceptable by commercial pulp and paper financiers who might be interested in the development of the industry in New Zealand. Most unexpectedly, the Government 9* j e x United States of America was round to be interested in some of the problems involved in the work, and the •forest Service entered into an agreement Ti< e j y the forest products laboratory at Madison, Wisconsin, the foremost pulp and paper research institution of its kind in the world, undertook to study the pulping and paper-making properties of a number of our woods. Mr Alexander R. Entrican was deputed to assist w-ith the work, and to make an industrial survey of the pulp and paper business in North America. V LABORATORY AND MILL TESTS. The laboratory tests initiated at Madison eventually proved so successful that the Government decided to carry the study to a logical conclusion by extending its scope to include a mill scale test under commercial operating conditions. This latter study included a pulping and papermaking trial at the Ladysmith (Wisconsin) plant of the Great Western Paper Company. The results of the laboratory and mill trials are discussed concurrently. WOODS TESTED.

Of the woods studied, two species are indigenous to New Zealand —rimu (Dacrydium cupressinum), a softwood, and tawa (Beilschmiedia tawa), a hardwood and four introduced softwoods—insignis pine (Pinus radiata), Austrian pine (Pinus austriaca), Corsican pine (Pinus laricio), and European larch (Larix europea). The two native species —rimu and tawa —and the introduced softwood —insignis pine—were studied more intensively than the others, the rimu because it is the most widely distributed and commonly used softwood in New Zealand, and the insignis pine since it is the most widely propagated species in the extensive man-made forests established by Government and private interests. The tawa was studied not only, as the principal hardwood of the North Island forests, but as being typical of a group of hardwoods—they all have the same type of fibre—such as bluegum (Eucalyptus globulus) and Tasmanian stringybark (E. obliqua). From a pulping point of view a softwood differs from a hardwood primarily in the shape of its fibre, that of the softwood being comparatively long and slender, with a uniform crosssection throughout its length, while that

of the hardwood is very much shorter, thick at the centre of its length, and tapering away to fine ends. The three remaining woods—Austrian and Corsiean pine and European larch, are some of the minor species included in the Forest Service plantations; Other species included in the Government and private forestation efforts are Douglas fir (Pseudotsuga Douglasii), and western yellow pine (Pinus pondcrosa), but in view of the previous studies on these woods made by the Madison Forest Products Laboratory further work was considered unnecessary. HOW WOOD IS PULPED.

In general there are two principal methods of pulp manufacture—mechanical and chemical. The mechanical is accomplished by pressing short logs of wood from which the bark has been removed against a rapidly revolving grindstone. The axis of the log is placed parallel to the axis of the stone, which is kept cooled, and the pulp removed by a shower of water sprayed continuously on the stone face. The product is -variously termed wood pulp,” “ ground wood,” or “ mechanical pulp,” and finds intensive use in newsprint paper, cheap catalogue and book papers and boards. Ordinary newsprint “ furnishes ” contain from 60 to 85 per cent, of it, the amount being limited only by the strength requirements of the sheet, which are met by certain admixtures of chemical pulp. Obviously the production of pulp by this means is cheaply done. The principal items of cost are the power used in grinding, and the wood. The product, however, is of a somewhat evanescent character. Containing, as it does, all the wood substance, it is subject to deterioration, and particularly to discolouration. It is thus limited to papers designed for temporary use, or for filling in with more durable fibres. Ground wood fibres, however, possess certain qualities of opacity and stiffness which are often valuable.

Chemical pulp is produced by removing all bark, decayed wood, and dirt, etc., from logs, chipping the cleaned wood, and cooking the chips with various liquors at high temperature and under pressure. For a light coloured fibre s litable for newsprint, etc., a sulphite liquor is employed; for dark, .tough fibres used in wrappings, etc., a sulphate liquor; and for light coloured hardwood fibres suitable for book and other bulky papers, a soda liquor. The chemicals dissolve away from the fibres the encrusting material which holds them together, so that, in general, fibres produced chemically are much longer and stronger than those produced mechanically, where one fibre is torn from another by the grindstone, and so considerably damaged in the process. PULPING TESTS—GENERAL. In planning the pulping tests, three major objectives were set up, their importance being considered in the order named:—

1. To produce a pulp or pulps suitable for newsprint. 2. To produce a satisfactory kraft pulp for wrappings, etc. 3. To produce bleached chemical palps for fine papers. In pursuance of the first ’objective, pulping tests were made by means of the mechanical, sulphite, and combined me-chanical-chemical processes, the greater part of the work being devoted to insignis pine and tawa as the most suitable species available. Rimu, larch, and all of the pines, were pulped by the sulphate process in order to evaluate their possible utility for kraft papers. Pulping tests by the soda process were limited to tawa. Bleached chemical pulps were produced from insignis pine sulphite and sulphate pulps, and from tawa sulphite and soda pulps. GROUNDWOOD PULPING TRIALS.

In general, ground wood pulps from insignis pine were found equal to spruce in yield and strength, but inferior from the standpoint of colour and dirt. The colour, of .course, is an inherent property of the wood, but the dirt is due to the prevalence of knots and core or pith rot, so that it should be controllable within certain limits . In the logs used for the original laboratory test, the cort rot was a serious factor, whereas in the second shipment used for the mill tests, it was almost negligible. Clearly the problem is one for the silviculturist to solve.

Being a hardwood, and very shortfibred, the tawa yielded a pulp much inferior in strength to both insignis pine and spruce. At the same time, the pulp was of good colour, and in the case of immature trees, comparatively free from dirt, so that for a filler it is fairly satisfactory. Even from the second shipment of pulpwood, comprising a fairly large proportion of mature logs in which a black discolouration was quite common, a fairly clean light-coloured pulp was obtained at the pulp mill, since the black dye proved to be highly water soluble. The tawa yield per cord was about 10 per cent, higher than in the case of spruce. Neither in the case of insignis pine nor of tawa was the power consumption for grinding excessive. The rimu was found too dark, and the larch and other pines too patchy to yield a satisfactory grade of groundwood. SULPHITE PULPING TRIALS.

Unbleached sulphite constitutes from 20 to 30 per cent, of the average newsprint paper, and in line with the major objective of the study, the principal effort in the sulphite pulping experiments was directed towards the production of a grade of pulp suitable for newsprint. Incidentally, some attention was given to the bleaching of the pulps produced, in accordance with the minor objective of producing a bleached sulphite stock. . Only three woods —rimu, tawa, and insignis pine—were successfully reduced by this process. The experiments with rimu indicated that this species can be readily reduced to pulp by the sulphite method, but the product is too dark for use in newsprint unbleached. It could, however, .be used for sulphite wrappings, etc. Insignis pine was reduced to a suitable quality of pulp for use in newsprint paper without bleaching, the yields and strength quality being comparable with those of sulphite pu’~ from white spruce. Although the pulp produced at the laboratory was inferior in colour to spruce pulp, that manufactured at the Ladysmith pulp mill almost equalled •' the commercial grades of spruce sulphite in colour. The yields-per cord, based on both the laboratory and mill tests, are fully as good as. those obtained from spruce.

Immature tawa was readily pulped under laboratory conditions, the nature of the product being determined by the cooking methods used. By employing an H-hour cooking schedule, a satisfactory pulp for book paper, bleaching easily, i.cts produced. Reduction of the total time to about nine hourr gave a pulp suitable for newsprint purposes, and obtainable in high yield. In the mill tests the large proportion of mature wood us:’d yielded a somewhat different class of pulp, still of good colour, but rather “ shivey ’’ in character. It was, however, actually refined without difficulty, and in all probability altered cooking condition! will reduce or even eliminate this small difficulty. The yields per cord in both series of tests were from 10 to 20 per cent, higher tha for spruce. SULPHATE PULPING TRIALS.

All five softwoods—rimu, Corsican pine, Austrian pine, insignis pine, and European larch—were reduced without difficulty by the sulphate method, and a pulp produced comparing favourably with the so-called “ Number One ” kraft pulp on the North American market.

Rimu produced the best pulp, with the woods following in the order given above. Rimu slabwood yielded a slightly inferior pulp to that secured from roundwood The semi-kraft process differs from the regular sulphate process in that the cooking liquor is impregnated into the chips under pressure prior to the steaming or cooking action, and all unabsorbed chemical is removed befre actual pulping begins. The chips are not completely pulped, but merely softened, the final pulping being effected by disintegration in a grinding device, such as a rod mill, li.mu, insignis pine, anA larch were pulped by this method, and tire savings in chemicals and increases in pulp yield are remarkable in view of the quality of the pulp produced, which, although darker and somewhat inferior to the straight sulphate pulps, is most promising for lower grades of kraft papers and boards.

•SODA PULPING TESTS. Pulping experiments by this process wert? limited to tawa. Not unexpectedly the tawa soda pulps were weak, but they possessed excellent bulk and opacity, and will serve for book and similar grades of paper. SEMI-GHEMICAL PULPING TESTS. Tawa was also pulped by the semichemical process, which is quite similar to the semi-kraft process already described, except that a neutral instead of an alkaline cooking liquor is used. The objective was a light-coloured pulp suitable as a substitute for the tawa sulphite pulp, but the stock produced was unsatisfactory for this purpose, both on account of colour and cleanliness, although having excellent possibilities in the field of fibre board, container and building boards, etc. PAPER-MAKING TESTS. Practically all the paper-making work, both in the laboratory and at the mills, was concentrated upon the production of newsprint from various pulps and furnishes. In the case of both wrappings and papers using sulphite or soda bleached stocks, the pulps were so similar to the standard North American and European pulps that extensive paper-making experiments were unnecessary, and only a few laboratory trials were made as demonstrations. All were quite successful. INSIGNIS PINE NEWSPRINT.

The first laboratory efforts to produce a newsprint, followed standard North American and European practice and combined varying proportions of groundwood and sulphite pulps, papers of corresponding “furnishes” being produced from both spruce and insignis pine. The insignis pine newsprint excceeded in strength the spruce newsprint, but was of somewhat poorer colour, and when made from pulpwood containing core rot, knots and blue stain, w'as dirtier. Cleaner papers resulted from pulpwood from which these defects were eliminated, and, when run over the printing presses of the Wisconsin State Journal, behaved exceedingly well, and W'ere declared by the publishers to be equal to the average commercial newsprin; in regard to colour, bursting s-rength, and printing qualities. Certainl” had the pulpwood used for the laboratory tests been as free from core or pith rot as that-used by the mill trials, the complaints as to dirt would have been much less serious, and perhaps even negligible. Summarised, it w’ould appear that a good commercial grade of newsprint, consisting of 25 per cent, sulphite and 75 per cent, groundwood, ma be produced from insignis pine.

INSIGNIS PINE—TAWA NEWSPRINT.

In their initial stages the efforts to produce a satisfactory insignis pine newssheet were discouraging, and attention was directed to the production of a new type of newsprint, based on a study of the theory of paper formation, and on Benjamin m Australia, on the use of hardwoods for newsprint. From this experiments by Miller in America, and work a theory was evolved and experiments instituted to test its soundness. In ordinary newsprint practically the whole of the tearing strength and a great part of the tensile strength, is given by the long sulphite fibres of the softwood.

Groundwood, on the other hand, contributes opacity to the paper, and gives it a good bursting strength. How to obtain the same results, using a mixture of softwood and hardwood pulps, was the problem to be solved. The experiments confirmed the theory that a small amount of long fibred insignis pine sulphite pulp (about 15 per cent.) should still be used to give tearing strength to the sheet, that hardwood sulphite from tawa (about 50 per cent.) should be substituted for a large part of the softwood groundwood to give bursting and tensile strength and that a fair proportion of hardwood groundwood from tawa (about 35 per cent.) should provide the necessary opacity. So successful were the initial experiments along these lines that attention w r as concentrated upon the problem of producing a combined softwood-hardwood newsprint, and eventually some very fine sheets equal to and better than the commercial softwood newsprint, were produced and run over the presses of the Wisconsin Journal. The laboratory test, however, lacked one very important essential. All the papers were produced on a slow running

machine, and considering the fact that this furnish of combined softwood and hardwood sulphites and hardwood groundwood was an altogether new one, it was thought advisable to extend this portion of the study to a commercial scale, and to have the paper produced on full sized fast running machines. The Government duly made arrangements to this effect through Mr Entrican and the Madison Forest Products Laboratory, a shipment of insignis pine and tawa being pulped by the Great Western Paper Company at its Ladysmith plant, and made into paper at the Wisconsin Rapids plant of the Consolidated Water Power and Paper Company. The commercial trial fully justified itself, not only in producing a newsprint whose colour, strength, cleanlines and finish were equivalent to that of standard news, but in solving many practical pumping and papermaking problems which had not been apparent in the laboratory tests ana which will be reflected in the design and operation of any pulp and paper mill which -may be foun 1 feasible in this country. One remarkable feature about the combined insignis pine-tawa pulps is the high finish which they may be given, sufficient indeed to make the paper useable for machine finish book or rotogravure paper. Some of this M.F. book and some dry finish wrapping paper was indeed actually produced at the conclusion of the. newsprint runs. FUTURE DEVELOPMENT.

Originally the study was made as one of the management problems in connection with the State forests and plantations. With its successful conclusion, the logical step is to initiate a further study which will cover the actual commercial possibilities of establishing a pulp and paper industry in New Zealand. In addition to making a study of the technique of pulping and papermaking processes, Mr Entrican has been engaged upon an investigation of the economical and financial as-ects of the industry, both in North America and Europe, and the Government will now carry his work to a logical conclusion by initiating a new study whereby he will be seconded from his usual duties to mak a detailed field examination of the commercial possibilities in promising localities. The study will cover wood supplies, transportation, chemical supplies, water, power and fuel, manufacturing and other facilities, labour conditions, etc., and will probably take some six months to complete.

A word of caution regarding the tendency to over-enthuse on the commercial possibilities of the industry is very necessary at this juncture. The industry is such a highly technical one, and involves such a large capital investment, that the utmost care must be exercised in its establishment in New Zealand, otherwise a precipitate failure will unduly prejudice the later development and expansion of the industry. To achieve economical results, mills should be of considerable size. For instance, the minimum size for a complete newsprint mill (i.e., both pulp and paper) is probably 100 short tons (20001 b per day. if not more, and this would involve a capital investment of about £1,000,000. New Zealand’s consumption of paper, however, is small, and further than that, the world market for both pulp and paper is in a parlous condition, and unlikely to recover for at least five years. Clearly we must proceed cautiously, and lay a sure foundation for the permanent wellbeing of the industry, relying in the early stages on our domestic and nearby markets. and leaving the development of world markets to a more favourable opportunity. APPRECIATION. Both the laboratory and pulp and paper mill trials have been beset with difficulties throughout, and an expression of appreciation is due to the staff of Madison Forest Products Laboratory for their tenacity of purpose in bringing to a successful conclusion a problem of no small magnitude. The members of the staff —all of them are prominent in different lines of pulp-and paper research —engaged upon the work were C. E. Curran, chemist in forest products; E. R. Schafer, associate engineer in Forest Products; W. H. Mc-nsson, associate chemist in Forest Products; G. H. Chidester, assistant engineer in Forest Products, and P. K. Baird, associate chemist in Forest Products. The work was supervised by Mr Clark C. Heritage, in charge of the section of pulp and paper, in co-operation with Mr A. R. Entrican, engineer of the New Zealand State Forest Service.