The effect of blind tooling rests largely on the depth and uniformity of the impressions (which makes it unsuitable for use with hard covering materials) and the ability of the heated tool to produce a darkened color (see above)—factors which make leather, especially in the lighter shades, an ideal medium for this method of decoration.
The critical aspects of the technique are the temperature of the tool and the degree of dampness of the leather. In general, the damper the leather the cooler the tool should be, and vice versa. In tooling leather blind, the surface is given a quick initial strike to "set" the leather in the impression. The tool is then impressed again and rocked slightly, which polishes and darkens the impression. When blind lines run across the spine of the book, polishing is accomplished by sliding a pallet along the lines; on the covers, where a fillet is used for long lines, it is fixed so that instead of rolling, it slides along the impression.
Blind tooling has been used as a means of decorating books since the early days of bookbinding, and can be traced back to COPTIC BINDINGS of the 7th or 8th centuries, and even earlier. There is reason to believe that the technique was brought to Europe from the Mediterranean area about the same time as other Coptic techniques being used, possibly by imported craftsmen; however, little is known of blind-tooled bindings until the 12th century and early part of the 13th. In one form or another, the technique has been used continuously up to the present day, but during the 16th to 18th centuries, its use was more or less limited to inferior calf- and sheepskin bindings. Near the end of the 18th and during the early years of the 19th centuries blind tooling was often used on fine bindings in conjunction with gold. Also called "antique tooling." (94 , 123 , 130 , 236 , 335 )