Warped / bowed:
Concave or convex distortion of hard materials such as wood, bone, ivory, horn, often due to swelling and shrinkage of the material, but material not actually bent, cracked or broken.
Often characterised by distinct white edged tide-lines, and there may be associated dye bleeding, running or loss of paint surfaces.
Water stains (Paper):
An area where tide marks are present indicating the object was exposed to water.
Loss of strength in the object that leaves it frail, fragile and liable to yield, break, or collapse under pressure or strain.
Gradual deterioration of the object’s surface by use or any continued process.
Shows signs of wear/continuous use.