The thickness of an unprocessed skin is more or less 5 mm. Since 5 mm is too thick to be processed, the skin is split lengthwise in two halves: grain leather (upper part) and split leather (under part).
It is possible to split at a chosen thickness: the minimum thickness for furniture leather is 1.0 mm. The most current thicknesses are between 1.2 en 2.0 mm. Exceptionally, furniture leather of over 3.0 mm is manufactured.