Pickled material is liable to deteriorate in storage. TFL has solutions to prevent mould growth, and to hide the effects of creases that form when the hides are baled.
Sheep and goat skins are frequently traded in a preservation pickle condition. In this state they can be considered as "raw material" for some tanners.
Creases and mould
This type of stock is often prone to creases caused by drying or long periods of storage "setting in " folds and trap marks. These creases do not relax easily and will leave permanent marks through to finishing. The condition can be much improved by acid bating prior to tanning or continuation of storage.
Mould on pickled stock is another major problem and if not treated can result in mould spreading throughout the tannery. Mould growth produces buffer systems which will increase the pH of the pickled stock thus increasing the possibility of more mould growth. If there is insufficient salt content in the pelts the increase in pH can ultimately cause putrefaction of the pelts effected.