The critical point drying autoclave in the AFCAL Lab is used in one way of drying wet sol-gels. Once the precursor chemicals are combined, they are left alone to sit and gel. Once the liquid gels, the sol-gel is placed into a methanol bath. After sitting in the methanol bath, the sol-gel is placed into the autoclave. It is cooled to 4� C and filled with liquid CO2. The CO2 is drained using a valve and replaced every 8-12 hours for 2-3 days. This process removes the methanol from the sol-gel and replaces it with CO2. After the solvent exchange is complete, the autoclave is heated to about 40� C to raise the CO2 to its supercritical point. Once the high temperature is reached, the gasses are slowly released and an aerogel is made.