Book Cloths (starch-filled and impregnated) Group Weight A Light B Medium C Heavy C-1 Heavy Buckrams (starch-filled and impregnated) Group Weight D Light E Medium F Heavy
The specific (minimum) requirements for these fabrics are as follows below:
Group Stripped-cloth Warp plus filling Breakings strength Breaking weight—not threads per inch— sum (warp plus strength— less than: not less than: filling—not not less less than: than: Pounds Pounds Ounces/square yard Warp Filling A 1.7 92 60 38 15 B 2.1 104 77 50 20 C 3.4 104 105 55 42 C-1 4.2 94 120 64 48 D 4.7 58 110 65 35 E 6.0 106 165 100 55 F 7.9 110 200 120 70
The breaking strength sum for embossed cloths has been established as 25% less than the figure for cloths that are not embossed.
Pyroxylin treated fabrics, which were introduced in about 1910, represented a major breakthrough in book cloth. The term "pyroxylin treated," as applied to book cloths, means either pyroxylin coated or pyroxylin impregnated cotton fabrics. The difference between the two is the quantity of protective coating applied and the manner of application, as well as the type of material treated. The pyroxylin composition consists of gelatinized nitrocellulose, a plasticizer to impart softness and flexibility, coloring matter, and a solvent. The fabrics used for impregnation are lightweight muslins, while those used for coating are heavier drills, twills, and sheeting. Coated fabrics are sometimes embossed in imitation of leather. The surface of impregnated fabrics retain the texture of the base materials. Pyroxylin impregnated fabrics are superior to starch-filled fabrics because their surfaces are more water resistant, they are more resistant to insects and fungi, and are generally stronger. They wear well and are particularly suitable for use in library binding. Pyroxylin coated fabrics are used extensively in edition binding because of the decorative effects obtainable. They, too, are water repellant and immune to insect attack and fungi, but they do not wear as well as impregnated cloths because of cracking at the joints and occasional peeling of the coating.
Book cloths for cheaper editions are closely woven, lightweight, starch-filled cotton fabrics, sometimes lightly embossed to conceal the weave of the fabric. They are generally attractive but have little strength or durability. They are also vulnerable to water spotting and soiling, and cannot be wiped clean. In addition, they are generally unsuitable for printing by offset lithography.
The book cloth used in library binding is generally of two types, pyroxylin impregnated and starch filled. The Library Binding Institute specifications for impregnated cloth, i.e., buckram, call for a base fabric of cotton, the warp yarns of which are to be woven in pairs, and with specifications the same as for group F, above. In addition, the Institute requires that the dye used must penetrate through the fabric so that both sides will be covered equally prior to the application of the impregnating compound (except in the case of "linen" type finishes). The impregnating compound must be uniform and homogeneous and be of either the nitrocellulose or cellulose acetate type. The weight of the impregnating compound must constitute at least 10% of the total weight of the finished fabric and must contain no oxidizable oils. The plasticizer, including oil (if any), must not exceed 20% by weight of the impregnating compound, nor must the weight of the pigment exceed 25% of the compound. Residual solvents, if any, are not to exceed 0.01% by weight of the finished fabric, and the pH of the cloth, as measured by standard methods, is not to be less than 6.5 nor more than 7.5, except in the case of the use of acid dyes, in which case the pH must not be less than 6.0. Cloth specifications state that the finished cloth shall be sufficiently water resistant to permit no penetration of water within a period of ten minutes, as determined by the ring test. The finished cloth is to be sufficiently grease resistant to permit no penetration of oleic acid within a period of five minutes, as determined by the ring test. The finished cloth must be capable of adhering permanently to boards and board papers under normal processing using either an animal glue or a resinous adhesive, and must resist rub-off to the degree that loss by abrasion shall not exceed 8% by weight of the fabric, when subjected to abrasion for 10 minutes by flint paper (2/0), on a disc 2 inches in diameter rotating at 1,250 rpm under 3 pounds of pressure. The finished cloth is to be free of marked odor, and its fastness to light shall be such that it will not lose color or fade when subjected to fadeometer exposure for 15 hours.
Cloth as a covering material for books is said to have been introduced, in England, by William Pickering, possibly as early as 1821-23, although books bound in burlap go back to the 1760s. Pickering's cloth was calico, a soft clothing material which disintegrated in the presence of glue unless it was lined with paper.ARCHIBALD LEIGHTON is generally credited with being the first to introduce a really durable cloth for covering books. The first true book cloth was a dyed and glazed calico, prepared with a starch filler to make it resistant to the moisture in glue.
The first cloth had little character and was aesthetically unpleasant. It was also without natural texture and the threads gave it a somewhat raw and unfinished appearance. What was needed was some sort of decoration which would make the threads less obvious. When this came about, it took the form of embossed grains worked on the material, either in the roll or piece. One of the earliest designs, introduced in 1831, was a water finish, which may have been an outgrowth of the watered silk patterns that were introduced in 1828; it was used only for a short period because of its high cost and poor durability. See also:CLOTH GRAINING .
For several years following the introduction of cloth, it was the usual practice of binders to buy the cloth in its basic white color, and then have it dyed, filled, and otherwise prepared for use, or to dye and finish it themselves. Embossing was done at first by means of ribbon embossers, but this was expensive, and the larger binderies did their own embossing by means of manually operated, heated rollers. By the 1840s, however, the complete manufacture of finished book cloth had become a separate business.
Notwithstanding its obvious advantages, it was not until the middle of the 19th century that cloth largely replaced paper in regular edition binding. The rapid increase in the use of cloth was largely due to the successful methods that were developed of blocking in gold on cloth-covered cases. It was then possible to give cloth bindings a finished appearance which enabled them to be compared favorably with hand-tooled leather and, therefore, acceptable as a permanent binding. (71 , 89 , 147 , 187 , 188 , 209 , 236 , 264 , 286 , 326 , 341 )