The shrinkage temperature (ts) of skin and leather objects is being systematically investigated at the canadian conservation institute (cci). The ts is related to the original treatment of the skin and is lowered by deterioration. Very low values indicate those items liable to irreversible shrinkage in the presence of humidity. (rh, water mist and humectants are currently under suspicion of provoking this shrinkage). Monitoring of objects on display can also indicate continuing deterioration, particularly photo-chemical deterioration of skins and leather in lighted displays. A description is given of the cci technique for determining ts. Multiple measurements are made, then averaged.