A patent for "certain improvements in sizing, glazing, and beautifying the materials employed in the manufacture of paper, pasteboard," etc.,was taken out in 1828 by Messrs. De Soras and Wise; and as the process possesses novelty, and is in successful operation at the latter gentleman's mill at Maidstone, we annex the following particulars, which we have obtained by a perusal of the specification. -A. ley is prepared with quicklime, the subcarbonate of soda (or potash), and water, in a vessel of white wood, until the alkaline solution shall be of 104° specific gravity, water being considered as 100°. With this solution a copper is to be about one-third filled, and heat applied, either by naked fire, or by steam; but the latter is, of course, preferable. There is now to be added of white bleached wax an equal weight to that of the solution, and the whole to be stirred until a perfect union or solution of the wax is effected: if, after a boiling of three ours, this should not appear to be the case (which will easily be discerned after a little experience, and without waiting till the materials have become cold to determine the fact), then a little more of the alkaline ley may be added, by degrees, to complete the operation: this being done, and while the solution of wax is boiling hot, there is to be added more water, in the proportion of four gallons to every pound of wax in the solution, and the boiling continued.
While this is going on, the starch of potatoes, in the proportion of from four to four and a half pounds to every pound of wax employed, is to be separately mixed in a gallon of water, and thrown into the copper, which, being stirred up, the whole contents of the vessel will almost instantly assume the consistency and colour of a very fine white paste, in which state it will keep good in summer for about fifteen days. The paste, prepared as above described, is to be used in the ordinary way of sizing paper, varying the quantity with the quality of the rags operated upon. If the rags be of the coarsest kind, about 3 lbs. of the pasty solution to 120 lbs. weight of rag in the pulp will suffice; if of middling fineness, about 4 lbs.; and if the very finest rags, about 5 lbs. of the paste. Previous, however, to the mixture being made into paper, a quantity of alum in solution, equal in weight to the wax employed, is to be mixed with it The mixture is now ready to be made into paper, either by hand or by machines, in the usual manner. After the sheets are formed, it is advisable to dry them as speedily as possible by free exposure to the air, and not to hang more than two or three sheets upon one another, which should be parted before pressing.
It is also recommended, that the felts used in the subsequent pressing of the new-made paper, be wetted in a weak solution of alum, and squeezed out by the press; and that the sheets of paper be two or three times alternately pressed and parted, by which process they will acquire a beautifully firm and glossy surface. The patentees likewise direct, that the couching felts be not washed out with soap, but with the ley, whenever required. Although the weight of the potatoe flour is given in the dry state, there is no occasion to dry it (which is a tedious operation), but employ it in the moist state, in which it deposits itself at the bottom of the vessels. Potatoe flour, in drying, loses 30 per cent of water; which weight of water should be deducted in calculating the weight of flour employed. As several kinds of paper require only small quantities of sizing materials, those points must be regulated by the knowledge of the manufacturer.
The manufacture of stout and beautiful drawing-boards has occupied the especial attention of Mr. Steart, of De Montalt paper-mills, Coomb Down, near Bath, who received an honorary medal from the Society of Arts, Manufactures, and Commerce, for the communication of his process, which we have abridged as follows, from the Transactions of the Society. - The extra stout drawing papers, or card boards, as they are usually denominated, are always made by pasting several sheets of paper together in the manner of a common pasteboard, and afterwards bringing them to a smooth face, by pressing and rolling. The pasting is a dirty operation, and the occasion of many defects, some of which are fatal to the degrees of perfection and nicety required in a good drawing board. Another great defect is, that the far greater part of the drawing and writing papers now in use in this country, are of a hollow or spongy texture; this arises from their being made of an indiscriminate mixture of linen and cotton, the greater elasticity of the latter preventing its fibres from closely uniting with those of the wax; the consequence is, an irregular surface, and a porous, spongy substance, very different from that which an adherence to the good old-fashioned practice, of using fine linen rags only in the manufacture of superior papers, would produce.
The lino-stereo tablet is entirely free from these objections for the following reasons: - first, it is not composed of several sheets pasted together, but is moulded from the pulp of any required thickness, in one entire mass; thus the risk of pasting is avoided, and no separation of the component parts can possibly take place, though wetted ever so often; secondly, instead of being composed of linen and cotton, it is wholly and solely manufactured from the best and purest white linen rags, most carefully selected, and, consequently, without the aid of chloride of lime, or any bleaching process whatever.
The process, - In selecting the raw materials for the manufacture of the lino-tablets, great care is taken to preserve the best and purest white linen rags only, rejecting all muslins, calicoes, and every other article made of cotton The linen rags are then carefully sorted, overlooked and cleaned, washed, and beaten into pulp, in the usual manner practised by paper-makers of the first class. The pulp being ready, and diluted in the vat with the proper proportion of pure water, the workman, dipping his mould first into the vat, takes it up filled with pulp to the top of the deckle, and holding it horizontally, and gently shaking it, causes the water to subside, leaving the pulp very evenly set upon the face of the mould; having rested it for a moment or two upon the bridge of the vat, the compresser, with its face downwards, is now carefully laid upon the sheet or tablet, and both together placed in the small press close at hand, where it is submitted to a very gentle pressure, in order to exclude a great proportion of the water remaining in the sheet; it is then withdrawn; the compresser and the deckle are then both taken off, and another workman couches it by very dex-terously turning the mould upside down, and pressing it pretty hard with his hands on one of the fine felts previously laid upon a very level pressing plank, by which means the tablet is left on the felt.