Leather Manufacturing Processes – How is Leather Processed?
Leather production is a laborious process. The leather becomes usable by going through many processes. You can view the video of Stahl, which explains the stages of leather from raw leather to finished leather.
In general, you can read the leather processing steps below. Leather manufacturer, technologist, engineer, technician; By designing and modifying these process steps, it obtains the leather with the desired character. It can make leather as hard as wood or as soft as fabric. Leather processing steps are given below as standard, but changes can be made during and during these processes according to the desired leather character.
LEATHER PRODUCTION STAGES
CONSERVATION: After the skin is peeled from the animal, it becomes extremely open to bacterial activity and begins to deteriorate rapidly. To prevent this, the skin is protected by various methods. The most applied method is the salting of the skin. With the salting process, the water level of the leather is lowered and bacterial activity is prevented.
WETTING-SOFTENING: With the soaking process, the natural swollen structure of the skin is regained and the dirty materials, soluble proteins and substances used for the conservation process are removed from the skin.
HAIR REMOVAL – LIME: The hairs on the skin and the epidermis layer are removed, the natural oils in the skin are saponified, and the active groups that will enable the tanning materials to bind and form a solid structure are released.
ELEMENT ( KAVALETO ): The hypodermis, which is the oily layer of the skin that is exposed to swelling by the liming process, which is not important in leather production, is mechanically removed from the skin.
SPLIT (From Lime): It is the process in which the skin, which is very thick than desired, is split from the cross section to obtain the skin part to be used in the actual leather production.
LIME REMOVAL: It is the process of removing the lime that is chemically or mechanically attached to the leather by the calcification process.
SAMA: With the use of specific enzymes, the type of proteins that do not work in leather production are dissolved.
DEGREASING: It is the process of reducing the oil ratio to a level that will not cause a problem for leathers such as sheepskins with high oil content.
PICK: It is the process of acidifying the leather so that the chrome tanning materials can go down to the leather section and perform the tanning process.
TANNING: It is the transformation of collagen, which is the main ingredient of the leather, which has been purified as much as possible in the previous processes, into a solid structure that can be used without decomposition and putrefaction.
ASORT: It is the process of classifying tanned leathers according to quality characteristics such as skin condition, etc.
Squeezing: It is the process of mechanical removal of excess water from the skin.
SPLIT (After Tanning): It is the process in which the skin, which is very thick than desired, is split from the cross section to obtain the skin part to be used in the actual leather production. Thus, the skin is brought closer to the desired shaving thickness. In addition, the split leathers obtained are evaluated in various ways. If the skins are split from lime, they usually do not split after tanning.
SHAVED: The leathers are adjusted to the desired finish thickness mechanically.
NEUTRALIZATION: It is the process of reducing the acidity of the leather so that the dyes, fillers and lubricants to be used in the further processes can work well into the leather.
RETENAGE: It is the processing of the leather with various synthetic and/or herbal substances in order to have the desired fullness, firmness and strength. Thus, the tanning process is improved.
DYEING: It is the process of coloring the leather with various types of dyeing agents.
LUBRICATION: It is the process of treating the leather with various lubricants in order to transform it into a usable form with the desired softness and handle.
OPEN TIGHTENING: It is the process in which the skin is mechanically dehydrated and opened.
DRYING: It is the process in which the skin is made dry by lowering the moisture level with various methods.
FINISHING: It is a wide stage that covers the processes in which the desired properties are achieved in the finished leather. The leather is given its final state by finishing processes.