Chemicals Used in Leather Processing

The following is a list of chemicals commonly used in leather making:

Beamhouse and Tanyard

Biocides

Biocides prevent the growth of bacteria which can damage the hides or skins during the soaking process

Surfactants

Surfactants are used to help with the wetting back of the hides or skins

Degreasers

Degreasers help with the removal of natural fats and greases from the hides or skins

Swell regulating agents

Swell regulating agents help prevent uneven swelling of the hides or skins during liming

Lime

Lime is used to swell the hides or skins

Sodium sulphide

Sodium sulphide chemically destroys the hair on hides or skins

Sodium hydrosulphide

Sodium hydrosulphide chemically destroys the hair on hides or skins. It does not create as much swelling as sodium sulphide

Low sulphide unhairing agents

Low sulphide unhairing agents help to reduce the amount of sulphides used in a tannery thus reducing the environmental impact of tanneries

Caustic soda

Caustic soda is used during the liming process to help swell the hides or skins

Soda ash

Soda ash is used during the soaking or liming processes to help raise the pH of the hides or skins

Liming auxiliaries

Liming auxiliaries reduce the wrinkling or uneven swelling of the hide during the liming process by helping with the even penetration of the liming chemicals into the hide

Ammonium sulphate

Ammonium sulphate is used during the deliming process and helps remove lime from the hides or skins

Ammonium chloride

Ammonium chloride is used during the deliming process and helps remove lime from the hides or skins

Organic - acid deliming chemicals

Organic - acid deliming chemicals are used to replace traditional ammonium salts when deliming hides and skins. They thus help reduce the ammonium salt pollution in tannery wastewaters

Sodium metabisulphite

Sodium metabisulphite is used during the deliming process and helps prevent the formation of toxic hydrogen sulphide gas during deliming. It also acts as a bleaching agent

Formic acid

Formic acid is used during the pickling process to lower the pH of the hides or skins. It acts as a buffer and helps prevent a very low pH during the pickling process

Sulphuric acid

Sulphuric acid is used during the pickling process to lower the pH of the hides or skins. It is a very strong acid and results in a very low pH during the pickling process is used on its own

Salt

Salt is used during the pickling process to prevent acid swelling of the hides or skins

Salt-free pickling chemicals

Salt-free pickling chemicals are used to replace the traditional use of salt in the pickling process. They have a significant impact on reducing the salts present in tannery wastewaters

Sodium formate

Sodium formate is used during the tanning process to assist with the penetration of chromium tanning salts into the hides or skins

Chromium sulphate

Chromium sulphate is the tanning agent used to make wet blue

Aldehyde tanning agents

Aldehydes are tanning agents used to make wet white

Magnesium oxide

Magnesium oxide is used during basification and raises the pH of the hide or skin to allow the chromium or aldehyde to chemically bind to the skin protein

Sodium bicarbonate

Sodium bicarbonate can also be used during the basification process to raise the pH of the hide or skin to allow the chromium or aldehyde to chemically bind to the skin protein

Fungicide

Fungicides are chemicals that are used to prevent the growth of moulds or fungi on tanned hides or skins

Dyehouse

Surfactants / Wetting agents

Surfactants help in the wetting back of the wet blue or wet white in the dyehouse. They reduce the wetting back time and also help clean the wet blue or wet white, removing dirt or machine grease or oil

Degreasers

Degreasers help remove grease or fats that may be present on the wet blue or wet white as a result of the wet blue or wet white coming into contact with tanning machinery

Sodium formate

Sodium formate helps raise the pH during the neutralization process

Sodium bicarbonate

Sodium bicarbonate helps raise the pH during the neutralization process

Neutralizing syntans

Neutralizing syntans help raise the pH during the neutralization process

Formic acid

Formic acid reduces the pH for the rechroming process or helps with chemically fixing dyehouse chemicals to the leather at the end of the dyehouse processes

Chrome syntans

Chrome syntans are used during rechroming to improve the softness of the final leather and improve the dye levelness

Chromium sulphate

Chromium sulphate is used during rechroming to improve the softness of the final leather and improve the dye levelness

Syntans

Syntans are used to give properties such as softness, fullness, roundness to the leather

Resins

Resins are used to give fullness, good lightfastness and a tight grain to the leather

Polymers

Polymers are used to give fullness, good lightfastness and a tight grain to the leather

Dyes

Dyes are used to give the leather a colour desired by the customer

Dyeing auxiliaries

Dyeing auxiliaries help disperse the dyes evenly giving better dye penetration and a more level colour

Fatliquors

Fatliquors are oils that are added to leather to give softness to the final leather

Finishing

Acrylic resins

Acrylic resins give specific properties to the leather finish such as adhesion, water resistance

Butadiene resins

Butadiene resins give specific properties to the leather finish such as good coverage

Polyurethane resins

Polyurethane resins give specific properties to the leather finish such as good toughness and good lightfastness

Fillers

Fillers help fill small blemishes on the leather surface and prevent the leather sticking to the embossing plate or roller when it is embossed

Dullers

Dullers help reduce the gloss of the finish

Crosslinkers

Crosslinkers are used to toughen the leather finish and improve the water resistance properties of polyurethanes

Handle modifiers

Handle modifiers are used to give the leather surface a waxy or slippery feel and help improve some of the test performance results

Nitrocellulose lacquers

Nitrocellulose lacquers are used in the top coat of a leather finish

Acrylic lacquers

Acrylic lacquers are used in the top coat of a leather finish

Polyurethane lacquers

Polyurethane lacquers are used in the top coat of a leather finish

Viscosity modifiers

Viscosity modifiers are used to increase the viscosity of a finish mixture

Pigments

Pigments are colouring agents that help hide defects on the leather surface

Dyes

Dyes are colouring agents that are used to slightly change the colour of the leather finish or to give the leather finish a more natural look

Defoamers

Defoamers are used to prevent bubbles from forming in the finish mixture