Firstly, as the general population became more affluent and educated, the demand for books increased. This was unfortunately also at the same time that, with the increasing trade with the colonies , European tanners started using the cheaper leather and tannins coming in from Africa and India. The result was that the majority of leather bound books from the later half of the last century up until the 1920s were bound in Catechol tanned leather such as Mimosa and Quebracho. Another important factor was the use of sulphuric acid. Sulphuric acid is a strong acid, and as such it s presence increases the likelihood of acid damage to the leather.
Artificial dyes require to be fixed to the leather.
In the case of shaving, the problem this caused was iron staining. Nowadays tanners have a wide variety of sequestering agents available to allow the removal of iron particles, however in the 1800 s the easiest way to remove iron was to bleach the leather using sulphuric acid. This bleaching not only left the iron in the skin but also the strong acid, both of which would have a detrimental effect on the future stability of the tannage. These pollutants increased the amount of acid in the air, and therefore the speed of acid damage to the leather. This was more critical in Catechol tanned leathers where the amounts of buffer salts are negligible.