158 



CdiKulidii Forestry Journal, April, 1C)20. 



The manufacture of newsprint 

 paper begins with the tree, so that it 

 is of the greatest importance to take 

 good care of Canada's forests, whose 

 spruce and fir form the foundation of 

 the paper industry. When the wood 

 arrives at the mill, cither by floating 

 down the rivers or hauled by rail, it 

 must be sawed into blocks from two 

 to four feet long, and the bark re- 

 moved. For newsprint paper this is 

 usually done by tumbling the blocks 

 in huge barrels made of steel angle 

 irons. Part of the barked blocks go 

 to the groundwood mill and the rest 

 to the sulphite mill, since newsprint 

 paper contains approximately 80% of 

 groundwood pulp and 20% of sul- 

 phite pulp. 



Making Pulp on a Grindstone. 



In the groundwood mill the blocks 

 are held by hydraulic pressure flat 

 against a revolving grindstone, and 

 the fibres are rubbed off. Everything 

 that was in the wood — and often 

 other things besides, remains in the 

 pulp. The pulp from the grinders is 

 mixed with water and screwed 

 through strainers to remove big sliv- 

 ers, knots, etc., and most of the water 

 is then removed to make less material 

 to handle. In some plants the thick 

 pulp is pumped directly to huge stor- 

 age tanks in the paper mill or further 

 dewatered and formed into sheets 

 which are folded into bundles or 

 ■"laps" containing about 35% fibre. 



Wood is Cooked to Make Sulphite 

 Pulp. 



The first operation in the sulphite 

 mill is to chip the blocks into small 

 pieces to facilitate the penetration of 

 the cooking liquor. The liquor is pre- 

 pared by burning sulphur and dis- 

 solving gas in lime water or in water 

 which is trickling over limestone in a 

 tower. The solution is bi-sulphite of 

 calcium, hence the name "sulphite" 

 for this kind of pulp. 



The chips and cooking liquor are 

 fed into huge boilers or digesters. 

 The cooking is done by steam for 

 about eight to ten hours. By this 



pnx-ess ab(jut one-half the solid mat- 

 ter in the wood is removed, lea\ing 

 (inly tlie comj^aratively pure cellu- 

 lose fibre. A cord (A wood yields ap- 

 pniximately r)ne-half ton of ^ul])hite 

 ]iul|), wliilc llie s.'inu' cord would yield 

 about a ton f)f groundwood ])\\\\k 



\\'hen llic cooking is c(jmplete th:; 

 chi])s are blown from the digester to 

 a blow-pit where they strike a plate 

 and are broken down to a pulp form. 

 The pulp is washed to free it from re- 

 sidues of the cooking liquor, and the 

 non-cellulose constituents of the 

 wood. After being washed, the pro- 

 cesses of the screwing, thickening, 

 etc., are practically the same as for 

 ground wood pulp. 



The Paper Mill is an Interesting 

 Place. 



One would hesitate, to believe that 

 the milky-looking liquid passing the 

 paper machme screens, through slats 

 only ten thousandths of an inch wide, 

 could possibly be formed into a pro- 

 duct which could be used for printing 

 the daily news or for wrapping a par- 

 cel. Yet such is the perfection of the 

 paper machine and the skill of the 

 paper maker that this wonderful re- 

 sult can be accomplished with in- 

 dividual fibres averaging only an 

 eighth of an inch, or less, in length. 



In the most modern mills, where 

 the production is kept high and manu- 

 facturing costs low, the pulps are 

 simply run from the "slush" storage, 

 in the proper proportions, into large 

 mixing tanks, from which it goes to 

 the paper machines. Many mills still 

 use the original mixer, the beater, 

 and necessarily so where the pulp is 

 handled in laps. In the beater the 

 fibres are brushed and rubbed be- 

 tween a revolving roll and a station- 

 ary plate, a process which, besides 

 mixing the fibres, improves their 

 papermaking cjuality. 



The mixed pulps or "stuff" is run 

 into storage tanks, called stuff chests* 

 Ml the machine room and pumped to 

 a regulator which allows just the 

 right amount to flow continually to 

 the paper machine, the excess going 

 back to the chest. Before the stuff 



