The Chemistry
Figure: Cross Section showing the Collagen in hide
After it is stretched and dried, the hide is ready to be sewed and then smoked to help preserve the texture and strength of the hide.
During the tanning processes, collagen again serves as a major component in the sciences behind the transformation of hide to leather. The thicker inner skin of the hide in an animal, the corium, is made predominantly of the fibrous protein collagen. In each technique of tanning, the solutions aim to react with the collagen, making cross-links, which convert the hide into leather. In chrome tanning (which derives its name from one of its main components, basic chromium sulfate (CrOHSO4)) the solution is fixed into the hide with a pH of 3.8-4.0 (with a higher concentration of sodium bicarbonate (HNaCO3), an acid to balance the pH.)
As more HNaCO3 molecules are added, outweighing CrOHSO4 moles. Through this process, the chromium solution is fixed into the hide by attaching to the carboxyl groups in collagen, which form the cross-links that transform hide to leather. Leather tanning, as a rather complex process, has various components, all of which share a reaction to the hide, (mainly the collagen) to help preserve and strengthen the bonds between the leather molecules.
Figure: The optimal cuttings of a hide. Note: the bends are mostly used for larger clothing