On an outside pair of leaves the guard should be inside, so that the glue may catch any ragged edges; while on the inside pair the guard should be outside, or it will be found to be troublesome in sewing. In handling the pasted guards care is needed not to stretch them, or they may cause the sheet to crinkle as they dry.
Plates must be guarded round the sections next them. When there are a great many plates the back margin of each, to which a guard will be attached, must be pared (see fig. 11, A), or the additional thickness caused by the guards will make the back swell unduly. In guarding plates a number can be pasted at once if they are laid one on another, with about an eighth of an inch of the back of each exposed, the top of the pile being protected by a folded piece of waste paper (see fig. 12). To paste, the brush is brought from the top to the bottom of the pile only, and not the other way, or paste will get between the plates and soil them. Guards should usually be attached to the backs of plates, and should be wide enough to turn up round the adjoining section, so that they may be sewn through. Should a plate come in the middle of a section, the guard is best turned back and slightly pasted to the inside of the sheet and then sewn through in the ordinary way.
If plates are very thick, they must be hinged, as shown at fig. 11, B. This is done by cutting a strip of about a quarter of an inch off the back of the plate, and guarding with a wide guard of linen, leaving a small space between the plate and the piece cut off to form a hinge. It will save some swelling if the plate is pared and a piece of thinner paper substituted for the piece cut off (see fig. 11, C). If the plates are of cardboard, they should be guarded on both sides with linen, and may even need a second joint.
A book that consists entirely of plates or single leaves must be made up into sections with guards, and sewn as usual. In books in which there are a great many plates, it is often found that two plates either come together in the centre of a section, or come at opposite sides of the same pair of leaves. Such plates should be guarded together and treated as folded sheets (see fig. 13).
In order to be sure that the pages of a book to be guarded throughout will come in their proper order, it is well to make a plan of the sections as follows, and to check each pair of leaves by it, as they are guarded:--