Thermal and moisture resistance

The dry thermal resistance (R_ct) is calculated using an equation involving the temperature difference between the face and back of the fabric, the surface area and the time of measurement.

The water vapour resistance (R_w ) of textile fabrics is calculated using an equation involving the water vapour pressure difference across the fabric, the surface area and the time.

Both modes of measurement are under static conditions.

Water Vapour Tranfer Index ((i_mt) from DIN 54101):

i_mt = 0 no water vapour transfer;

i_mt = 1 water vapour transfer corresponding to an air layer of equal thickness.