The book is then trimmed in a cutting or trimming machine; formerly the edges were trimmed by a knife called a plow while the book was clamped firmly in a press. Before cutting the back is struck forcibly against an iron plate, to square up the signature, then placed against gauge, set to position desired and clamped, knife descending and cutting book while under pressure. After trimming the three sides the book is again carefully knocked up and a thin coating of glue, sometimes flex ible in character, is well rubbed in between signatures, for unless this is done the signatures will show a tendency to split open, where one signature joins another. The book is then rounded by drawing or shaping the curve, at same time beating in a peculiar manner with a flat-faced hammer, then damped in pair of jaws, and the joints drawn over by repeated taps of hammer, or in some shops by a heavy roller set in a machine called a backing ma chine, which 'clamps the back under treadle movement. Many extra forwarders round the book before trimming, then knock the round out. After cutting, the book will spring back to its former round, leaving the front concave. In most particular classes of work the boards are laced to book before it is cut. The book is now laced to boards forming the cover and the ends of cords glued down on the inside of the cover. If the edges are to be marbled, gilt or colored, they must go through that process before books are rounded.
Marbling.— Prepared colors are thrown in a shallow trough containing gum tragacanth, on which the colors float and spread as desired. The pattern is formed by various combs that mingle the colors. The edges of the book are dipped into the liquid just deep enough for the colors to adhere, and when removed from trough, a sizing is drained over the edges, re moving the surplus gum and fastening the col ors more securely to edge. After edges are thoroughly dry they may be burnished with an agate or stone burnisher. Gilding is done by laying thin sheets of gold leaf on the edges of books previously scraped and smoothed with steel scraper and fine sandpaper and sized heavily with a preparation of white of egg. When dry it is then burnished with blood stone, flint and agate burnishers.
Colored Mix aniline colors with alcohol, adding a little ammonia to drive color in, spread over surface of edges with a fine sponge. If desired, then clamp in press and burnish. The book is then ready for the head bands, linings and cover. The headbands are
merely ornamental and are woven with a col ored silk, by machine or made over cords with muslin. The older process was to work over a piece of parchment with colored silks and partially fasten to back of book in the weav ing or sewing. The back is then lined with strong paper glued on, the amount of stiffen ing varying with the size of book and style of binding, most books being made with loose backs on which false bands are glued.
The leather cover is dampened and covered with paste, then drawn smoothly over and turned in, over boards which have previously been laced to the book. After leather has dried, clean out joints and paste against covers the lining papers.
Artistic taste of the highest order finds employment in this branch of book binding and an expert finisher must be at once artist and craftsman of much ability. The ornamentation and lettering of fine bindings all are done by hand, the finisher bringing into use many tools and ornaments, cut on brass and fastened into small wooden handles, much de pending on the manner of cutting and shaping the tools. The leather must first be prepared with paste wash and a glair or sizing generally made from the white of an egg, over which the gold leaf is laid and the tools which are heated over a gas burner are then impressed on the gold leaf, the surplus gold being brushed off with a piece of crude rubber. 'Upon the most careful preparation of leather, the proper heat of tools and the tooling of book before sizing is too dry, depend the brilliancy or gloss of the impression.
Ornamentation without gold is called /blind tooling° and is produced by rubbing or stamp ing the hot tool on the dampened leather. Few books bound now have such a wealth of orna mentation and so great an amount of time given to the finishing as was common in Grolier's time, although there are still many novel effects produced by the use of inlaid colored leathers, incised leather, etc.
After the period of Grolier, the taste for magnificent binding in France ran riot and many indulged in most sumptuous bindings and designs were prepared under the superintend ence of the most celebrated artists.
During the 16th and 17th centuries bindings were produced in England which compared favorably with the contemporary masterpieces of French, Italian and German bibliography, but in the 18th century England took the lead place in the workmanlike forwarding and artistic finishing of books.