Sleeked leather, jacked leather, finishes, glassing
LEATHER FINISHING METHODS
Glazed aniline finishes
One of the oldest and yet most beautiful types of leather finishes is the glazed aniline finish. The method was developed early in the history of leather manufacture because of the readily available materials and the advantages that could be gained from hand working.
The leather is coated with the material and allowed to dry. The dried leather is then placed on a glazing jack, a piece of machinery equipped with a solid cylindrical piece of glass, approximately two inches in diameter and six inches long. The machine is made in such a way as to allow fast stroking of the surface of the leather by a reciprocating arm. The pressure on the leather can be controlled and the surface of the leather glazed to the degree desired b~ control of the number of strokes in a particular sure on the leather can be controlled and the surface of the leather glazed to the degree desired by control of the number of strokes in a particular area and by the pressure applied. By this system the operator can bring up good color tones and a high gloss finish in different areas of the skin as needed. The friction of the glass rubbing across the finish develops high temperatures which promote hardening of the finish and, at the same time, a quick smoothing action which results in a high gloss finish. The high temperature of the glazing jack also causes darkening of the colors and raising of some of the oils in the leather. The characteristics of a glazed finish are high gloss, smooth surface, and subtle undertones of color. Since the finish itself involves no pigment, the porous fiber structure of the skin can be seen. It is possible to “look down into the leather” and perceive that the finish is part of it1 providing depth and beauty. The disadvantage of a finish of this type is the high cost of application. It may be necessary to apply as many as six different coats involving several glazings, platings, and staking and brushing operations to bring about the desired physical characteristics. Reproduction of glazed finishes by modern mechanized processes is very difficult, but even today large quantities of leather are being made with the process. The use of such finishes is confined to the more expensive types of leathers, such as reptile, kid, and high-grade calf. The base color for a leather to be made into glazed finishes is usually that obtained by the vegetable tanning process. The leather finisher then develops the final color by tinting the leather on the surface with a preliminary coat of an aniline dye. A basic dyestuff is generally used because of its strong affinity for the vegetable tanning material and because of its ability to develop shading of color on final glazing treatment. After application of the aniline dye, a protein is applied, in this case the globular.
The names used for this type of finish are as follows: Sleeked (done by hand with a copper tool), and Glassing (done by hand when a lump of glass is used as the glazing tool).
A jack is the tool used in a machine to duplicate the hand process. This same machine could be used to do several types of finishes, such as a pumice rod for buffing, and boarding and graining operation.
This picture shows a jacking machine in operation.
This is a dangerous machine and many operators lost their thumbs.
A picture of a jacking machine and below it the different tools that could be used be the machine.
This is a picture to show the type of finish that was achieved by this method of finishing.
Leather Preservation Please follow this link for more information on the care and feed of leather.
Leather Preservation for leather tanned before 1890
David Jarnagin's 19th century leather definitions Page
If you have any question please contact me.
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