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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

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

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

Sulphuric acid
Sulphuric acid is used during the pickling process to lower the pH of the hides or skins

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

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

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 in the dyehouse

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

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 leathet

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

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

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

Polymers 
Polymers are used to give fullness 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

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

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

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