The Chemistry of Leather

Introduction

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Leather is solid substance created from an animal hide and several different chemicals used by humans in everyday life. I chose to find the chemistry of leather because it is something that is underappreciated in the world we live in today. Leather impacts people in ways they do not even know. Much of the shoes we wear or even some clothing is made of leather. Leather is also used in many recreational purposes or sports, like the balls used for the games. Leather can be something enjoyed as simple as a couch to lay on.


Composition of ...

  • Sulphuric Acid - H2SO4

  • Ammonium Sulphate - (NH4)2SO4

  • Ammonium Chloride - NH4Cl

  • Salt - NaCl

  • Magnesium Oxide - MgO

  • Chromium Sulphate - H24Cr2S3O24

  • Chrome - Cr

  • Lime - Ca(OH)2

 


Main Chemicals, Compounds, Components

  • Chromium: One of the main chemicals used in the tanning process. There is three types of chromium used: Metallic,Trivalent, and Hexavalent. Chromium is used to create the tough resistant surface of leather.

  • Lime: The main use of lime in making leather is that it is the number one substance used for cleaning the hide before it is tanned. Lime is a chemical mostly made of calcium carbonate. It removes the hair, proteins and even some layers of the skin on the hide so it can be tanned.


Chemistry's Role

  • The chemistry of lime consists of certain natural elements combined with one another to make the final substance. Lime is consisted of calcium carbonate and calcium hydroxide.

  • Chromium is a natural element that is mined throughout the world. Chromium can be mixed with other elements as well to bring out different compounds.

  • All in all, the most important part of leather is the hide itself, because without the hide, there will simply not be any leather no matter how many chemicals are used. For the most part, leather is mostly made from natural substances with the exception of man-made substances to make it more presentable and higher quality.


Background Research

  • Leather was first used as footwear, clothing, shelter, or other necessities from hides that humans needed to survive

  • One of the oldest used resources going back to the cave man days

  • Leather adapted and was used in nearly every pair of shoes in its early stages

  • There are 4 steps to creating leather: Preparatory stages, Tanning, Crusting, and Surface Coating

  • All leather comes from a hide from some animal

  • Modern day shows that leather is used in many different ways like furniture and even recreational purposes

  • There are many different types of leather as far as the strength and stability that they withstand

  • Chrome tanned leather was invented in 1858

  • Leather is typically high priced because of the durability it holds within it

  • The quality of leather has greatly increased over the years with advanced technology


Resources

https://en.wikipedia.org/wiki/Leather_production_processes

  • 3 sub-processes: preparatory stages, tanning, and crusting

  • Tanning is when the proteins in the hide are transferred into a stronger more stable material

  • Most common tanning material is chromium

http://www.all-about-leather.co.uk/what-is-leather/where-does-leather-come-from.htm

  • alum , oil, and oak bark was used to tan leather until acids and chemicals were discovered

  • Earth salts were used as a tanning substance for leather

  • Leather is broken down into different parts of animal hide it came from. For Example: Proteins, fats, water

  • Protein is mainly a substance called collagen

https://www.ischool.utexas.edu/~cochinea/pdfs/t-brewer-04-sc6000.pdf

  • Surface coatings of leather experience a number of different oils and lubricants as parts of the finishing product to soften the hide and make it more comfortable

  • Liquid coatings are more difficult to use than creamy coatings

  • Trichloroethylene is a toxic chemical used in the cleaning process of raw hides

https://sites.google.com/site/isttschool/useful-information/chemicals-used-in-leather-processing

  • Lime is used to increase the product of the hides or make them swell

  • Sodium sulfide eliminates all the hairs on the hides

  • Hides are soaked in water to preserve the skin back to its original state

  • Machines are used to remove all the excess fats and proteins of the hides

http://www.theecologist.org/News/news_analysis/1651375/toxic_chemicals_used_for_leather_production_poisoning_indias_tannery_workers.html

  • Tanning leather is a very toxic process due to the chemicals used

  • Leather is made many different ways in India wear it is a big part of their culture

  • As found before acids and chromes are used in tanning the hides

http://www.peta.org/issues/animals-used-for-clothing/leather-industry/leather-environmental-hazards/

  • Leather is actually harmful to the ecosystem because of the chemicals needed to make it

  • Workers that work in the tanneries also are harmed by the chemicals and even sometimes killed by them

  • Arsenic is a very common poison and is actually used in most tanning industries

http://www.leatherresource.com/history.html



About the Author

Gabe Sulser is a junior at Billings Senior High School. He plays football and runs track and field for the Broncs. He enjoys playing football the most and was apart of the 2016 State Championship team. Gabe holds a high standard in the classroom  holding a weighted 3.98 GPA along with serving the school in Senior Advocates.









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