When leather gets wet, oils in the leather that keep the protein bonds between the leather fibers from getting brittle bind with the water. Water releases the oils near the surface of the leather, making the leather fibers less supple.
Wet leather can be rescued if action is taken while it is still damp. A leather conditioner should be applied to the wet leather. The conditioner seeps through the pores left open by the evaporating water, replacing the oils and lubricating the leather. If the leather has dried out, the conditioner will not be able to penetrate the pores and the leather will turn brittle.