Leather types and production process classification
Leather is made from animal skins that have been processed by a range of physical and chemical methods. The process of making leather from rawhide (the original skin stripped from an animal) is called tanning.
Tanning is a complex process with a long lead time. The tanning process is generally divided into three stages: the preparation stage, the tanning stage and the finishing stage.
(1) The main processes in the preparation stageThe main processes include soaking, deboning, dehairing, ashing, degreasing, softening and acid soaking. The main purpose of the preparation stage is to remove some components of the raw hide that are not beneficial to tanning, such as hair coat, blood stains, fat and some soluble proteins. It also loosens and softens the collagen fibres of the raw hides to facilitate processing in the later stages. (2) Tanning stage
The main processes include pre-tanning, tanning and re-tanning. This stage is the key stage of tanningThrough the tanning process, the collagen fibres undergo structural changes, i.e. they are transformed from raw (raw) leather to leather that can be preserved for a long time and has a functional use. (3) Finishing stage
The main processes include chipping, neutralising, dyeing, fatting, drying, spreading, buffing, finishing and embossing. This stage is mainly for finishing the tanned leather to obtain a variety of different colours of leather. For example, after dyeing, finishing and embossing you get leather of different colours and patterns, and by smoothing, fattening and filling you get leather of different thicknesses and different degrees of softness.