Читать книгу The Art of Paper-Making - Alexander Watt - Страница 6

Table of Contents

TREATMENT OF RAGS.

Preliminary Operations.—Sorting.—Cutting.—Bertrams' Rag-cutting Machine.—Nuttall's Rag-cutter.—Willowing.—Bertrams' Willow and Duster.—Dusting.—Bryan Donkin's Duster or Willow.—Donkin's "Devil."

Preliminary Operations.—Before the rags are submitted to the various processes which constitute the art of paper-making, they are subjected to certain preliminary operations to free them from dirty matters, dust, and even sand, which is sometimes fraudulently introduced into rags to increase their weight. This preliminary treatment may be classified under the following heads, namely:—Sorting; Cutting; Willowing; Dusting.

Sorting.—The rags being removed from the bags or bales in which they are packed, require first to be sorted according to the nature and quality of the fabrics of which they are composed; thus linen, cotton, hemp, wool, &c., must be carefully separated from each other; the thickness of the substance, its condition as to the wear it has undergone, and the colour of the material, all these considerations are taken into account by the women and girls who are employed in the operation of sorting. The finer qualities are set aside for writing-paper, inferior sorts being used separately, or mixed, according to the requirements of the manufacturer. Blue rags are generally separated from the rest and kept for the manufacture of blue paper, but most of the other coloured rags require bleaching. In sorting rags, a good deal of judgment and skill are required to avoid mixing the better qualities with those of an inferior class, which would occasion loss in the manufacture. It is also important that those of inferior colour should not be mixed with the finer qualities, which would be liable to affect the colour and deteriorate the quality of the paper. Paper manufacturers generally classify the rags obtained from home sources, that is, from different parts of the United Kingdom, under the following heads:—

Home Rags.

New cuttings.

Linen pieces.

Cotton pieces.

Fines (whites).

Superfines (whites).

Outshots (whites).

Seconds (whites).

Thirds (whites).

Colours or prints.

Blues.

Gunny, clean.

Gunny, dirty.

Rope (white).

Rope (hard).

Rope, bagging, etc.

Foreign rags are distinguished as below:—

Belgian Rags.

White linens.

Mixed fines (linens and cottons).

Grey linens.

Strong linens.

Extra fine linens.

Blue linens.

Superfine white cottons.

Outshot cottons.

Seconds.

Half jute and linen.

Light prints.

Mixed prints.

Blue cottons.

Fustians.

Black calicoes.

White hemp, strings, and rope.

Tarred hemp, strings, and rope.

Jute spinners' waste.

Jute waste.

New.

White linens.

Grey linens.

Blue linens.

Unbleached cottons.

White linens and cottons.

Print cuttings (free from black).

Blacks.

Fustians.

French Rags.

French linens.

White cotton.

Knitted cotton.

Blue cotton.

Coloured cotton.

Black cotton.

Marseilles whites.

Light prints.

Mixed prints.

New white cuttings.

German Rags.

S. P. F. F. F.

S. P. F.

F. F.

F. G.

L. X. F.

L. F. R. blue.

C. S. P. F. F. F.

C. F. B. blue.

C. F. X. coloured.

Trieste.

P. P. white linen (first).

P. white linen (second).

S. fine greys.

X. coloured cottons.

Leghorn.

P. L. linens.

P. C. cottons.

S. C.

T. C.

Turkey and Beyrout.

Bright reds.

Alexandria.

Whites. Blues. Colours.

Baltic and Russian.

S. P. F. F.

S. P. F.

L. F. B.

F. G.

F. F.

B. G.

L. F. X.

Woollen rags are only used to a very moderate extent in blotting and filtering papers and also in coarse papers and wrappers. Many attempts have been made to bleach woollen rags, but the severity of the treatment required invariably ended in a destruction of the fibrous substances mingled with them. It is customary to dispose of such material for re-making into common cloths, and for shoddy. Rags collected in large cities, in consequence of the frequent bleachings they have been subjected to, are considerably weakened in fibre, tearing easily, and are therefore subject to loss in process of manufacture into pulp. Country rags, being coarser and greyer because less bleached, are stronger in fibre and give a better body to the paper. In sampling rags it is necessary to take precautions against the fraudulent "tricks of the trade," which are often resorted to to cheat the manufacturer. Samples should be taken from the interior of the bags or bales, to ascertain if the material in the interior is equal in quality with that at the outside—that is to say, that the quality is fairly averaged throughout. It may also be found that the rags have been purposely wetted to increase their weight. If such is found to be the case, a few handfuls should be weighed, and then dried in a warm room, and afterwards re-weighed, when if the loss exceeds 5 to 7 per cent. it may be assumed that the rags have been fraudulently wetted. It is generally found, however, that the merchants in the principal towns transact their business honourably and are therefore reliable.

The sorting is generally performed by women, who not only separate the various qualities of the rags, which they place in separate receptacles, but also remove all buttons, hooks and eyes, india-rubber, pins and needles, &c., and loosen all seams, hems and knots. The rags are next carefully looked over by women called over-haulers, or over-lookers, whose duty it is to see that the previous operations have been fully carried out in all respects. Usually there is one over-hauler to every eight or ten cutters.

Cutting.—In some mills it is preferred to have the rags cut into pieces from 2 to 4 inches square, but the actual size is not considered of much importance. The chief object is to have them in such a condition that they may be thoroughly cleansed in subsequent operations, and able to float throughout the water in the rag-engine, without twisting round the roller. If the rag pieces are smaller than is required to effect this it tends to create a loss of fibre in the operations of willowing and dusting.

Fig. 3.

The process of cutting is performed by hand or by machinery. When the rags are cut by hand, the operation, which is accomplished by women, is conducted as follows:—The cutter takes her place in front of an oblong box, as in Fig. 3, covered with coarse wire netting, containing three threads per inch, through which dust, &c., passes to a receptacle beneath; in the centre is fixed, in a slanting position, a large-bladed knife of peculiar form, with its back towards the operator, who is surrounded by a number of boxes, corresponding with the number of the different qualities of rags; these are lined at the bottom with coarse wire gauze. In the operation of cutting, if any foreign substances, such as buttons, hooks, &c., which may have escaped the sorters are found, these are at once removed. The rags as they are cut are put into baskets to be conveyed to the rag-engine room. In some mills rags are cut by machinery, but hand cutting is usually adopted for the better kinds of paper, as it is obvious that the machine would not be able to reject, as is the case in hand cutting, unpicked seams and other irregularities which may have escaped observation by the sorters and overhaulers. Machine cutting is, therefore, generally adopted for the materials which are to be used for the coarser papers. There are several rag-cutting machines in use, of which one or two examples are given below.

Fig. 4.

Bertrams' Rag-Cutting Machine.—The engraving, Fig. 4, represents a machine manufactured by Messrs. Bertrams, Limited, of St. Katherine's Works, Edinburgh, to whose courtesy we are indebted for this and other illustrations of their machinery, which have been reproduced in outline from their illustrated catalogue. The machine, which is suitable either for rags or ropes, has three revolving knives, and one dead knife, which is rendered reversible to four edges, and has self-acting feed gear, side frames, drum, and other connections of substantial construction; it is wood covered, and furnished with sheet-iron delivery spout. The material passes into the machine along the table at a, where it passes between the dead knife c and the knives b fixed to the revolving drum d. The cut rags fall into a receptacle beneath the drum.

Nuttall's Rag Cutter.—Another type of rag cutter, and which is also suitable for cutting bagging, sailcloth, tarpaulin, Manilla and other fibres, is Nuttall's Rag Cutter, a drawing of which is shown in Fig. 5. This machine is manufactured by Messrs. Bentley and Jackson, of Bury, near Manchester, and is generally known as the "Guillotine Rag Cutter," from the principle of its action, which is that of chopping the material. The machine is adopted at many mills, and a large-sized machine has recently been put down at the Daily Telegraph mills, Dartford. A medium-sized machine will cut about one ton of rags in an hour.

Fig. 5.

Willowing.—In some mills the cut rags are conveyed to a machine called the "willow," which in one form of machine consists of two cast-iron cylinders, 2½ feet in diameter and 3½ feet wide, provided with numerous iron teeth, which project about 4 inches. These cylinders are placed one behind the other, and beneath them is a semi-circular screw, and above them a cover of the same form. This cover is also furnished with teeth, and is so adjusted that the teeth in the cylinders pass those in the cover at a distance of ½ to ¾ of an inch. In front are a pair of rollers and revolving apron, which carry the rags into the cylinders, which rotate rapidly; and the rags, which are thrown by the first into the second cylinder, are allowed to remain in them for about 20 seconds, when a sliding door, which rises three times per minute, allows the rags to be discharged into a duster. Each time the sliding door opens the revolving apron moves forward and recharges the willow with a fresh supply. The rags, after being beaten and teazed in the willow, are considerably loosened in texture, and a good deal of dust and gritty matters fall through the screen beneath.

Fig. 6.

Fig. 6 represents a combined willow and duster, specially useful for waste rags and jute, but may be used for all fibres, manufactured by Bertrams, Limited, the main features of which are thus described:—"There are two drums, which have malleable-iron cross-bars and teeth, and malleable-iron harp motion below for escape of dust. The framework of the willow is of cast iron, and the sides are filled in with cast-iron panel doors, the top being covered in with sheet iron. The gear is arranged so that the willow will deliver to the duster or otherwise by self-acting motion continuously or intermittently. The feed to the willow can also be made continuous or intermittent. The drums, framework, panels, and casing being made of iron, the chance of fire from the friction of its working is reduced to a minimum. The duster, as a rule, is 12 feet long, about 5 feet in diameter, and has eight longitudinal bars of cast iron fitted between the front and end revolving rings. These bars are fitted with malleable-iron spikes, pitched and so arranged that the rags or fibres are delivered at the exit end automatically. The outside of the duster can be lined with wire-cloth, perforated zinc, iron, etc. It is driven by outside shafts and friction gear, so that there is no internal shaft to interfere with the delivery of the fibres."

Fig. 7.

Dusting.—In Fig. 7 is shown a rag-dusting machine, manufactured by Messrs. Bryan Donkin and Co., of Bermondsey, London. The cylinder of this machine, which is conical in form, to enable the rags to travel from one end to the other, whence they are ejected, revolves, as also does a second cylinder of a skeleton form, but in the opposite direction. Each cylinder is fitted with knives, or spikes—those of the outer cylinder projecting towards the centre; the knives of the centre cylinder being attached to its exterior surface: when the machine is in motion the two sets of blades pass each other so that when the rags come between them the action is that of scissors. When the rags are ejected at the end of the cylinder, they pass into another cylinder of wire, through which the dust falls and leaves them in a fairly clean condition, when they are lowered through a trap-door to the boiling room below.

Fig. 8.

Donkin's "Devil."—For removing the dust and dirt from coarse and very dirty rags, oakum, rope, etc., the presence of which would seriously injure the quality of the paper, a still more powerful machine has been introduced, called the "devil," which is constructed on the same principle as the willow, but revolves at a lower speed. The revolving axle of this machine is conical, and is provided with teeth, arranged in a spiral form. The case in which it rotates is fed continuously, instead of intermittently; and although it facilitates the subsequent treatment of the fibre, it is said to be wasteful, while also consuming a considerable amount of power. A machine, or "devil," for cleaning rags or half stuff is manufactured by Messrs. Donkin and Co., a representation of which is shown in Fig. 8.