Air pocket (light spot in or near the centre of the sheet) - Door gasket or throughput of the probe, or ventilator or pipe joint leaks. - Insufficient vacuum - Service needed Over sterilization - Temperature too high in relation to the pressure, or too long exposure time or both. Wet steam or non condensable gases (spots/figures/circle formed figure in the center) - Pressure or temperature or both too low. - Insufficient drying. - Steam contains non condensable gases, most often carbon dioxide. -—f* - Uniform black/dark brown in 134 oC cycle - Uniform black/dark grey in 121 oC cycle