Page:Paper and Its Uses.djvu/96

84 few cases of watermarked papers the watermark can be read from both sides of the sheet, but the general rule is that the right -side of the sheet is that from which the watermark can be read. In machine-made papers it is the upper side of the paper as it is made, but in hand-mades the right side is the under side which receives the watermark. The watermark is in reverse upon the mould or the dandy roll, and is fixed on the impressionable pulp by slight compression or displacement of the fibres. In papers without water-marks it may be taken that the smoother side is the right side. The wrong side of machine-made papers bears the impress of the woven wire upon which they were made. The wire mark is fixed by various means, such as the pressure of the dandy roll, the action of the suction boxes, and the pressure of the couch rolls. Blotting paper, although not subjected to all these forces, shows the wire mark so plainly as to serve as a guide to what one may expect to find in other papers which are more highly finished. Looking along the surface of the paper will sometimes reveal this mark, when it is not possible to detect it by looking through the sheet. The wire for hand moulds is much coarser than the wire cloth of the machine, and as the pressure of the pulp is not great, and the fibre is moderately long, couching nearly obliterates the woven wire mark and makes it less easy to distinguish between the right and wrong sides of hand-made wove papers. In a laid mould the wires displace fibres, and the paper is immeasurably thinner at the places where the wires of the mould occur, but these are the only wire marks on the paper. A dandy roll makes the laid wire marks on the right side of machine-made paper in addition to the woven wire marks on the wrong side, so the distinction between right and wrong sides is easily