BASIC – Leather Tanning


Apr 29, 2022

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The leather, called Hide for large animals like Cow or buffalo and called Skin for small animals like sheep and goat and exotics animals is an organic surface that covers the body of all living beings.  Its characteristics, strength, elasticity, softness and breathability are the ones that make it unique and superior to any material manufactured disposable so far.  The leather is a byproduct of the meat industry which means, after the animal is killed, the leather will be removed and immediately cured also said stabilized, so it will not putrefy and rot.  Layers of salt will be placed between these skins and refrigerated until delivery from the butcher to the tannery.  Once they reach the designated tannery, the salt will be removed and the leathers will be inspected for quality, weight and thickness.  After inspection the pre-tanning starts by soaking them in lime also called liming or soaking which chemically dissolves the hair, removes unwanted proteins and opens the fiber structure.  The leather will swell so we will pass them in roller blades in order to remove the bottom layers “ Fleshing “  making the thickness of the leather more regular and thinner.  Now we can trim the excessive undesirable parts at the edges by hand.  Now the leather is put into a special machine cutting the leather horizontally into two or more layers.  The Top layer because of the pores remaining from the hair is called Top Grain while the bottom is called Split.   Now they are place into a large rotating wooden Drum with chemicals transforming them into a durable product.  The chemicals used are mostly Mineral (Chromium salt or Aluminum salt) and Vegetable tanning.  Leather tanned with Chromium salt comes out wet and Blu color so they are called WET BLU.  The Wet Blu leather is cures and can be kept for the next process called CRUSTING.  The Crusting is the Wet Blu which is Dyed, Dried and ready for FINISHING.  Vegetable tanning instead use natural tannates coming from trees.   Mineral tanning is faster, lower in cost and easier and the leather will be softer so it is mostly preferred.  We will now have mineral Crust or Vegetable Crust.  At this point each tannery will have their own secret recipes to finish the leather to get the finished desired by its customers.

If the split is sanded with rolls having similar to sand paper it will have a velvety look and feel and called suede.  This is less expensive.  If the Top Grain is buffed, only few microns are sanded to get a velvety effect, it will be very expensive and only few specialized tanners are able to get this finish and called Nubuck.  If we buff the Top Grain, the defects tend to show more and so we need to utilize only the highest quality leather with closed grains.  The most expensive leather is the one with double finishing having the Top Grain finished and the reverse side with a suede finish.  Because of the double finishing also called Reverse calf, it is very expensive and usually used for lady shoes but not only.

PU split or Action Leather or Bicast  is a split leather where on top we apply a synthetic material with the designs or a top grain.  This is very economical.  We also have PU leather which is synthetic made in Labs so it is considered artificial leather.  Lastly we have bonded leather made from scrap of leather materials pressed together with glu into sheets.  Bonded leather is used for leather accessories and shoe counters.

FUNCTION:  The tannery will not only preserve the leather in time but will give its quality, thickness and color.  Tanners have learned from generation and long tradition to transform normal leather into masterpieces enhancing the richness of any shoe.

Italian Footwear Solution uses leather coming from the best tanners in the world ensuring consistency, comfort and timeless beautiful finish.

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