Oils & fats in the leather industry

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Oils, fats and waxes in the leather production

Greases, oils and waxes play an important role in the leather production process. They are used to help achieve certain properties (softness, waterproofing or appearance). Fats, oils and waxes are main components of leather care and are also sometimes used directly during tanning. The fat content in the leather after tanning is about 1 to 25%.


Fatliquoring (regreasing)

During the tanning process, the animal's natural fats are removed from the rawhide because, as they are not preserved, they will become rancid. To obtain a soft and stable leather, it must be re-greased. Going back to the origins of tanning, leather used to be re-greased with milk, brain, egg yolk, vegetable oil or fish transe (also called "fish oil"). Fats were also used for fat tanning. A finished oiled leather has a fat content of up to 25%.

Fatliquoring involves reapplying water-soluble oils to leather. This can be done in the tanning process or even after dry cleaning. The dry cleaning process is carried out in a solvent bath, which thoroughly degreases the leather. The fatliquor makes the leather supple and stable and gives a handsome appearance to the "starved" look of degreased leather.

Oils and fats affect the smell of leather. They are among many substances used in tanning which influence the smell of the finished leather. Fatliquors of good quality do not have an intrusive odour.


Raw materials for the fatliquoring agents

Sea animal oils: Fish oil

Land animal oils and fats: Claw oil, beef tallow, pig fat, bone fat

Vegetable oils and fats: Palm oil, sunflower oil, rapeseed oil, soybean oil, coconut fat, palm kernel fat, turkey red oil

Waxes: Carnauba wax, montan wax, wool grease

Synthetic fats: Paraffin oil, mineral oil, fatty alcohol, fatty acid ester


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Fish oil - Claw oil

 

Fats in leather care and finish

Leather is not only greased and oiled during production to make it supple and soft. Fats and oils are also used as leather care against wear (in particular, shoe polish), or to waterproof leather, or to preserve old and dry leather by re-greasing and softening.

Oils, greases and waxes are also used in the finish. For pull up (greased leather - waxed leather - oiled leather), these substances are used to achieve certain effects in the surface. Pull-up leather usually has patina which increases with time.


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Pull up leather - Waxed leather

 

Video about the treatment of hardened vintage car leather


How to soften old, hardened car leather.



Additional information


Video about the leather production


The leather production in a modern tannery.


Process steps in the leather production
storage - soaking - liming - fleshing - splitting - pickling - tanning - neutralising - withering - sorting - shaving - dyeing (through colouring) and fatliquoring - drying - finish - softening - final check


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