The board must, of course, be perfectly clean on the stretching side, otherwise the back of the mounted article would be soiled. If necessary, the surface may be covered with waste paper before stretching. The material should be left about 5 cm. larger all round for convenience of stretching and working. The stretching is best done with drawing pins, which may be used again and again for the same work. The method of stretching is as follows: Woven fabrics stretch less in direction of the warp than the woof, therefore stretching is begun in the former direction. The material is fixed with pins at two corners of one side, stretching it firmly at the same time. The material will be drawn outwards a little on the stretched side (Fig. 124). To counteract this, a pin is fixed in the middle of the opposite side, after having pulled the material over so that the side A forms a straight line. The whole side A is then pinned down, the pins not being more than 5 cm. apart (Fig. 125).
Now draw out the pin on the B side and pin down the whole side, firmly stretching the material all the while, beginning at the middle and working towards the sides (Fig. 126).
The third side is pinned down by first fixing a pin in the centre, then in the centre of the halves to right and left, then proceeding with the smaller divisions in the same fashion. The material is pulled far enough to form a straight line (Fig. 127). The last side is well stretched and pinned down as just described. In this way a surface not only entirely free from wrinkles and creases is produced, but the texture of the material will run straight.
In mounting upon cloth, special care must be taken that the paper is perfectly limp and flexible; but this must not be due to its having been too thickly coated with paste.
Large wall maps made up of many pieces must be very carefully damped and must be allowed to lie damp a long time. Attention must be given to the colours, which are apt to run, and also to the proper fitting of the various pieces, as these have often been stretched in various ways in the lithographic press, or through irregular drying have taken unequal sizes. Damping and pasting must be repeated to help to remedy this until the whole fits together perfectly.
Maps to be folded must be cut into sections of suitable size. In order that they may fold together well, the various pieces are set slightly apart, the horizontal lines slightly less (1-1/2 mm.), the longitudinal somewhat more, where there are many parts up to 3 mm.
Perfect fitting is here essential, and to insure this it is advisable to mark out the divisions with the folder and rule. This is not necessary for small maps, the eye will then be sufficient guide. Thorough rubbing down is absolutely necessary to make every part adhere.
When perfectly dry, the material is taken from the stretcher, the edges accurately trimmed, and the map folded upon the cross lines into one long strip, and then this strip is folded over in zigzag fashion to the given size.
The appearance of such a map is greatly improved by sharply pressing awhile, for which a zinc plate should be inserted between each fold.
Such maps are often placed in a small light case of cardboard covered with cloth, or a light cover is made, into which the map is so pasted at the back board that it lies ready for use when opened.