The Joh. Rendenbach Jr. Tannery has been producing oak bark sole leather in Trier, Germany since 1871. The leather is sourced from cattle in the Austrian Alps.
JR’s leather is tanned using the classical oak-bark method. A natural tanning method that uses an old 3 meter deep oak pit. This method uses vegetable tanning agents in the form of barks and fruits. This tanning process takes between nine and twelve months, depending on the thickness of the hide. The leather is tanned without mechanical movement, by keeping the temperature in a very specific range, and without adding chemical catalysts.
Among its benefits, the leather becomes lightweight due to the long tanning duration ensuring that the leather only absorbs the amount of tanning agent that is needed. Oak-bark tanned leather is known for the following unique properties: it is extremely hard wearing, tough, as well as flexible, making them a comfortable sole of excellent solidity, with a beautiful amber woody color. Some of its other qualities are:
Deodorant and antiseptic
Prevention against foot diseases
THE TANNING PROCESS
Tanning begins with the dye section. Stripped of its hair, the hide undergoes a slow surface tanning over a period of about four weeks, opening its fibers to absorb the tannin. The hides are passed through several pits, connected in a closed circuit through a system of pipes and containing different concentrations of tanning fluid. The hides themselves hang on frames and are moved manually from one pit to the next on a daily basis.
The second stage of the preliminary tanning involves a pit half filled with tanning fluid. The hides are submerged in the fluid with a layer of the shredded tan substances between each one. They remain here for approximately six weeks, after which the procedure is repeated in a second pit.
The oak-bark ground-tanning is an extremely gentle process taking place in old, three-metre deep oak lined pits. During the course of this process, tannin is absorbed into the hide binding and conserving its protein-structures. Nature supplies the main ingredients for the tan mixture used in traditional oak-bark ground-tanning; primarily oak, spruce and mimosa bark as well as valonea fruit.