Even in the 21st Century, the manufacture of leather retains an air of the dark arts, still somewhat shrouded in the mysteries of a millennia old, craft based industry. Despite the best efforts of a few scientists over the last century or so, much of the understanding of the principles of tanning is still based on received wisdom and experience. Leather is made from (usually) the hides and skins of animals – large animals such as cattle have hides, small animals such as sheep have skins. The...