Leather contains moisturising and lubricating oils which were added in the tanning process. These oils are gradually lost as the leather is used. The once plump and flexible fibres of leather gradually become thinner and more rigid.
Instead of flexing and stretching, the fibres become tight and stiff. In a similar fashion to bending a piece of metal repeatedly, they will eventually weaken and break, causing cracks.
Using an oil such as Neatsfoot Compound will revitalise the fibres in the leather so that they can move freely again, much like oiling an engine.
As a guide, apply one or two thin layers to the absorbent flesh side of the leather. The leather will become strong again, less brittle and less likely to snap.
CARRS LEATHER OIL
For excessively dry leather or leather in need of revival, an intensive conditioning oil such as Carrs Leather Oil is more appropriate.
Apply a thin coating to the flesh side of the leather and allow to soak in for at least 24 hours. Particularly dry tack may benefit from a thin, additional coating applied to the grain side, which will also help to restore the colour.
If the leather still appears dry another application may be required, however take care not to over oil, wiping off any excess as it cannot be removed once absorbed.
Over oiling ‘collapses’ the structure of leather, leaving a slick, oily feel. So little and often is more effective than a thick application.
Although cracks cannot be repaired, their appearance can be minimised by oiling and conditioning.