 In 1931, to develop the first aerogels, Kistler used a process known as supercritical drying which avoids a direct phase change.By increasing the temperature and pressure he forced the liquid into a supercritical fluid state where by dropping the pressure he could instantly gasify and remove the liquid inside the aerogel, avoiding damage to the delicate three-dimensional network.While this can be done with ethanol, the high temperatures and pressures lead to dangerous processing conditions.