PAPER MAKING

[Music] most of the world's supply of paper is made from the fibrous portion of wood hence the story of paper properly begins in the forest different species of trees are logged for pulpwood in different wooded areas in the united states and canada in this area in northern michigan spruce wood is for a paper mill in estates this camp is operated by a jobber who sells the logs to a mill at a specified price per cord after a hearty breakfast the woodsmen are ready for a strenuous day in the forest in the earlier days woodsmen usually received a monthly wage today their income is largely from piecework the men being paid by the log for sawing and by the cord for hauling note the homemade drains or sleds used for hauling the cut logs from the forest they are designed to slide easily over the snow covered ground the camp foreman marks off strips of timber for each sawyer by cutting a visible portion of the bark a daily record is made of each workers output some of the workers are professional woodsmen who spend most of their working years in the camps others are young men from the farms and villages who work in the woods only temporarily as a means of earning a stake the sawyers work singly each cutting down his own trees each tree is notched then sawed from the rear this method enables the sawyer to fell his tree accurately the many branches must be trimmed from the tree leaving a bare log several feet in length this log is then cut into standard lengths of eight feet these cut logs are then loaded onto the drays by another group of workers these men called haulers they moved the logs from the woods to nearby landings these haulers often own and maintain their own equipment paying for it out of their earnings earnings based on the number of cords hauled the powerful tractors employed must be kept in the best of mechanical condition as they are in continuous operation throughout zero and sub-zero weather these logging operations are carried out during the winter because snow is necessary to skid the logs from the woods to the landings horses once the sole means of transportation in the woods are being replaced at the woods landing the logs are loaded onto trucks by husky workers these men are known as truckers the trucks are often owned by their operators these men are also paid by the court for hauling the logs from the landings to the railway docks in this case 20 or more miles from the camp the strenuous test under which this equipment stands up is a tribute to modern science and industry however in spite of fine equipment hard physical labor still plays an important role in even the most modern of logging operations the spruce forests of ontario canada also furnish much pulpwood for the paper mills of the lake states the logs are floated down fast-moving streams skilled men are loosening logs stuck in the shallow rapids this work in the icy water requires strong sturdy men with great powers of endurance passing the logs over falls is a still greater problem loosening up a log jam like this requires skill and daring the problem may sometimes be solved by building flumes around the falls and shooting the logs through them to the river below after reaching the river mouth on the northern shore of lake superior the logs are drawn together and held in place by a boom which consists of logs chained together end to end from the boom the logs are loaded into large steel barges or boats by conveyor elevators these mechanical conveyors save much time and simplify the work of loading the huge boats each boat holds hundreds of cords of pulpwood although most of the loading is done by mechanical methods a number of workers are required to pack the logs in the hold to ensure the maximum load the use of boats results in a considerable saving as water transportation is much cheaper when shipping from canada from ontario the wood is taken to the paper making centers farther south this load has traveled by way of sault ste marie to the port nearest its destination where the wood will be transferred to cars derricks with huge grab buckets are used to load the railway cars in a relatively short time many cars are loaded and a train load of logs is on its way to the paper mill because of the large amount of water used in paper making the mills are usually located at or near a plentiful water supply adjacent to the mill is the wood yard where a large supply of wood is kept on hand immediately on arrival the cars are measured by scalars who accurately check contents and determine the number of cords for which the logging contractor is to be paid after the wood has been measured it is stored in the yard for future use to be used as needed the logs which have been in the wood yard longest are again loaded on yard cars which take them over to the paper mill on arrival at the log hall the wood is dumped on the moving conveyor which goes to the wood room in the wood room the long length logs are sawed into shorter pieces to facilitate easier handling from the saws the short logs known to the workmen as sticks are conveyed to the drum barker where they are tumbled vigorously for about 30 minutes to remove the bark for further barking imperfect logs are given finishing touches on this machine knots and other defective parts are removed in this knotter saw the sticks are separated at this point one kind for ground pulp the other for sulfite pulp in the sulfite process the wood which is to be reduced to pulp by chemical means is cut into chips the oversized chips are screened off for further reduction the chips of proper size are conveyed on belts to hoppers above the digesters large mills have a battery of several digesters as shown in this scene each with a capacity of many tons of wood and chemicals the digesters are charged from above with wood chips from the storage bins through a charging funnel which connects the bin with the digester the cooking or digesting is done under considerable pressure and at high temperature for a number of hours in this animated diagram showing the operation of a single digester is shown first the charging with wood in the form of properly screened chips which come through the funnel from the hopper above next it is charged with the bisulfite liquor which enters from below this liquor is an acid and is commonly referred to as the cooking liquor in the cooking process which is now shown the acid dissolves the parts of the wood other than the cellulose fibers which are then free to separate from each other after cooking for a number of hours the opening of a valve allows the stock which is under great pressure to blow out into a tank known as the blow pit the cooking liquor which contains all the dissolved portions of the wood is then drained off the fiber stock is thoroughly washed by repeatedly filling the blow pit with water and then draining it off after which it is sliced to storage tanks from the storage tanks the pulp in dilute liquid form is pumped to a series of screens it first passes through a screen known as the knotter which rejects the knots and coarse pieces of incompletely cooked chips much of the objectionable material is eliminated at this step it next passes through the thickener where some of the water is removed from the thickener the pump passes to a reserve tank next the stock goes to the unbleached stock screen where the remaining course materials are screened off the accepted stock is then passed through the decker where it is thickened to produce white paper stock for printing purposes the pulp is bleached as shown in this diagram the center screw mixes the stock with the bleach the degree of bleaching is regulated by the ratio of bleach liquor to pulp and by temperature and time after bleaching the pulp is pumped to washers where the dissolved coloring matter and spent bleach liquors are washed out after washing the pulp is screened again the accepted stock goes to the wet machines where the pulp fibers are formed into a sheet on a wire covered cylinder the fibers are picked up by a woolen felt blanket and are wound up on a press roll from which the pulp is removed in the form of sheets or laps this is the final stage in the conversion of wood to pulp by the sulphite process small trucks are used to transport the lap stock to the storage room back in the wood room the logs to be used for ground pulp are sorted out and conveyed to the storage room an operator on this floor is continually on duty to keep the elevators loaded with logs to be lowered to the grinding machine below the grinders are powerful machines each containing a huge grindstone such as this one the stone surface has been carefully prepared to ensure uniform pulp texture the stone revolves partially submerged in water which serves to lubricate the stone surface prevents overheating and facilitates removal of the fibers from the stone surface the revolving stone reduces the sticks to pulp as they are forced against it by hydraulic pressure at this point as is true all along the line tests are made to ensure uniform quality after screening and bleaching the ground wood pulp is ready for the beaters the beta room is the junction point for all raw materials that go into paper the operation of the beater may be observed in this empty beater a revolving cylinder with a number of blades causes the stock to circulate around the mid feather this action mixes the ingredients and cuts hydrates and brushes the fibers thus ensuring the best possible paper texture the beaters are charged with the ground pulp in a liquid or slush form clay alum rosin sizing and color are added then the sulfite lap stock is introduced all these operations are under the careful supervision of the head beater man from the beaters the stock goes to machines known as the jordans which subjected to a further beating this is the final treatment the stock receives before it goes to the paper machine in large mills such as this one there are a number of paper machines the refined stock diluted to more than 99 percent water is pumped in a continuous stream to each machine as it enters the machine the stock passes through screens to the flow box from here the stock flows over the fordreneer wirecloth belt this revolving endless belt screen is in constant agitation as the water is drawn through the screen the paper making solids or fibers are set into sheet form the upper portion of the four draineer wire moves toward the press section since a continuous stream of stock is spouted onto the wire a continuous web of paper is formed on its surface enough water is removed and the fibers are sufficiently compacted so that the sheet can support its own weight as it is transferred to the woolen blankets of the presses which press out more of the water the remaining water is removed as the paper is carried on an endless canvas over the steam rollers of the dryer section next along the line the coating materials are added then with further drying over heated polished steel rollers the paper finally passes through the machine calendars where pressure between heavy iron rollers gives the desired finish greater smoothness and gloss may be secured if desired by running the paper through super calendars the pressure on the paper as it passes between the polished steel rollers and hard pressed paper rollers produces the higher smoothness and better gloss in the testing stations samples of stock from the different stages of production as well as finished paper from the various machines are subjected to various tests in this laboratory finished papers are being tested for opacity for weight for tensile strength gloss and smoothness the permanence of the paper's coating is also being determined in a dusting test its ability to endure folding is measured in this folding machine if the paper is to be delivered as sheets it is sent to a cutter where a blade on a revolving cylinder cuts the roll paper into single sheets of the desired size when more exact sizes of sheets are desired the cutter stock is further trimmed paper leaving the cutters and trimmers is piled on skids for inspection the sheets are inspected and counted by hand all defective paper half sheets and so forth are rejected much experience goes into the development of the skills and dexterity necessary for such speedy work cutting trimming inspecting and counting the sheets are packed in cases and properly marked and labeled the cases are loaded directly into cars for shipment or stored for future orders if the paper is for roll stock it is marked with reference numbers wrapped in heavy paper weighed and then labeled for shipment most of the paper used in printing magazines is shipped in large rolls the use of electric trucks cranes lifts and other labor saving devices reduces the truly hard labor in the mill to a minimum with the role safely packed in the cars they are now ready to ship to all parts of the country tons of paper are used annually by all branches of the printing industry on arrival at the printing establishments the large rolls each weighing about a ton are placed in storage to be ready for immediate use each roll averages about 10 000 feet in length two rolls one above the other are placed on continuous rotary presses several magazine pages are printed on this continuous sheet later they are cut into sections ready to be inserted into final magazine form this high speed sheet fed press is printing five color reproductions using large cut sheets instead of rolls the printed sections or pages of a magazine are placed in the binding machine which gathers and binds sections in one operation the binding machine has completed the assembly operation and the conveyor takes the almost finished publication to the last operation cutting and trimming a large razor sharp cutting blade trims any remaining rough edges on the head foot and side of the magazine this is the story of manufacture and use of high-grade book and magazine paper the development of economical methods of making this paper is playing a tremendous role in placing a wealth of well-illustrated current reading material the reach of all who read