[10] Patine represents a veneer, or wash of colour, applied on the surface, or in the hollows of leather, to intensify its tone, or to give artificial effects, such as those of verdigris, rust, or antiquity.
Partly owing to its nature, and partly owing to the tanning process, leather is susceptible to the action of the dyes used to colour it in degrees varying according to their composition and penetration. We will not attempt to enumerate all the dyes that may be employed or to describe their composition. Excellent results can be obtained with ready made preparations, and some brief remarks on the subject are all that is necessary for the purpose of this work.
Practical experience alone is a reliable guide in the selection of dyes, as, whatever their base may be, they all vary greatly in use. It may be remarked that there are many aniline dyes which are more durable than vegetable ones, although there are others which merit their reputation for instability. The colour of dyed leather cannot be expected to remain unaffected by constant exposure to direct sunlight, but it should not alter with ordinary use.[11]
[11] See the remarks on Leather for Bookbinding in the Note at the end of this volume.
It is obvious that, in proportion as the colours sink into the leather, they will lose in brilliancy, but on the other hand, this very absorption, which allows colours to be
superposed and appear translucent, gives a depth rarely obtainable in materials of less capillarity.
13. Top of Casket covered with brown calf, cut and slightly embossed. By Florence Hornblower. Modern English.
The following notes are intended merely as a general indication of the manner of treating the various substances used in colouring leather.