Paintings, drawings in colour, or wash drawings cause exceptional difficulties, as the moisture of the pasting medium tends to dissolve or make the colours run. In such cases smaller sheets are placed between sheets of damp blotting paper, and it is stuck upon the pasted underside. When the object permits it, it is glued on without previous damping. Large tracings present the greatest difficulties as the paper stretches very much and, on account of its delicacy, is not easily manipulated and is liable to crease. Such work requires several hands. It is necessary to have clear paste, quite free from knots, which has been thinned to the consistency of thick pea-soup. When at all practicable, the tracing itself is pasted twice, the first pasting will make the paper stretch and the second ensures a proper coating of paste. Two persons lift the tracing and turn it over (for very large pieces four persons are required); the sheet is laid down at one corner, the other three being held up, and the whole gently lowered little by little. One person rubs it down slowly, proceeding from the first corner and carefully avoiding creases and bubbles.
With such big jobs it is often impossible to avoid tears near where it is held by the fingers of the workers unless timely precautions against this are taken. The simplest way is to paste strips of paper and to stick these on the four corners of the pasted side of the tracing and to take hold of these. These strips are removed as the rubbing down progresses, making sure, however, that there is still enough paste left on these places.
Tracings are always mounted upon white paper, even though it has afterwards to be cut or mounted on cloth.
Maps that have to be prepared for hanging on walls are always provided with a roller at top and bottom; these may be stained and varnished or covered with coloured paper. The mounted maps are glued and tacked to the half-round rollers. Where all round rollers are used they should be ordered in halves. The edges of the map are glued between and the two halves then nailed together. Rings are screwed into the top roller for hanging, and also a few tapes to tie up the rolled map if required.
Plates and maps, as also placards, are also varnished. Varnishing is nowadays always done with spirit varnish, which is convenient for working. All papers cannot be simply varnished and done with—the nature of the paper must be taken into consideration. All sized and chromo papers may be varnished without preparation. Many note-papers, especially unsized and copperplate papers, must first be sized, which prevents the resinous parts from penetrating and thus avoids grease spots.
The best of all means is glue or gelatine; the former turns the paper somewhat yellow. A thin solution is made, which is laid on warm with a large sponge in long quick strokes. Where colour or ink is to be dealt with, no parts should be touched twice or the colours will be effaced. A second coating, however, may be given after the first has dried. The spirit varnish to be used—called map or photo varnish—is still too thick as sold. It is thinned with 90% spirit of wine to the required consistency until it runs easily from the brush.
Wide varnish brushes with lead fastenings are used. Two coats of thin varnish are better than one coat of thick.
CONCLUSION.
Our work is now finished. The author has endeavoured to deal only with what comes within the sphere of practical bookbinding.