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On foam products
with porous covers, moisture doesn't increase as much as on most foam since the open cell
structure of the covers provides a pathway through which moisture can diffuse. Nicholson
showed that water vapor transfer rates were reduced by more than half when foam mattresses
were covered with non-stretch and two-way stretch covers (Nicholson, 1999). Patient
movement can increase transfer rates. Mean temperature increases of 3.4 degrees C and a
10.4% increase in moisture at the skin surface have been recorded by Stewart on foam
products after one hour of contact . |