TIGHT AND LOOSE BACKS
For years there has been a certain mild controversy regarding the relative merits of tight and loose backs for leather bound books. Tight backs are those in which the material used for covering the book is pasted or glued to the back. Loose backs are those which, by means of folded paper or a piece of paper put in as described on page 37, are prevented from adhering to the back. When the book is opened the back springs out. (Fig. 13.)
The tight back book always forms a hinge at the place where the book is opened. Since the place of the hinge is constantly changing the back of the book after much use becomes concave instead of convex, and the appearance of the book is seriously marred. Also the constant creasing of the back tends to erase the gold lettering, so that it becomes indistinct. If labels are put on they speedily come off. It is customary to use tight backs on very heavy books, though there are cases where such books have been put in loose backs.
Figure 13.—Tight back and loose back.
The loose-back book always preserves its shape and good appearance, even when the paper on the inside may be so badly worn that the book should be withdrawn. The strain, however, always comes at the joint; therefore if poor leather is used it will quickly wear out at this point.
Each method has its advocates, but so far as the present writer can learn, there seems to be little to choose from the standpoint of strength. It might seem that the tight-back book would be the stronger, but as a matter of fact in actual wear loose-back books seem to hold their own with the others. In fact when the soft, spongy papers are used the loose backs are obviously stronger. It seems clear that there is little choice one way or the other, and the question must be decided by the personal preference of the librarian.
JOINTS
In library binding French joints are now used in place of regular joints. Figure 14 shows plainly the difference between the two. In the regular joint it will be noticed that when the book is opened there is a sharp crease in one line from head to tail. In the French joint the strain is distributed over a much greater area. In regular joints the leather is sometimes pared at the joints to permit of easier opening of the book. In French joints the full thickness of the leather can be used. French joints are made by setting the boards away from the back about one-eighth of an inch. When the cover is put on it is necessary to crease between the board and the back while the leather is still damp.
An excellent illustration showing the anatomy of a joint may be found on page 51 of Dana's "Notes on bookbinding for libraries," ed. 2.
A Section of an Ordinary Joint with the board open shows that the creasing of the leather is concentrated on one line.
A Section of a "French Joint" shows how this creasing is distributed over a great surface, and so enables sufficient flexibility to be obtained with much thicker leather than can be used with an ordinary joint.
Figure 14.—French joint. From Report of the Committee on Leathers for Bookbinding. Edited for Society of Arts, London, 1905.