Final answer:
Autoclave wrapping material must be permeable to allow steam to circulate properly around the instruments during sterilization.
Step-by-step explanation:
Autoclave wrapping material must be permeable so that steam can circulate around the instruments. During the autoclaving process, which involves moist-heat sterilization, the necessary conditions include temperatures typically at 121 °C or 132 °C and pressures of 15 to 20 psi. For effective sterilization, steam must have direct contact with the items being sterilized, which is why containers holding the material must be left loosely closed, and the instruments should be loosely wrapped. This ensures the steam penetration is optimal and endospores are effectively killed, achieving complete sterilization.