This is also sometimes described as dry cleaning, but it's a wet process actually. First the cleaning solution is mixed with some carbonated water, and after that they apply it to the carpet as a mist. Then they use the so called “bonnet” which is a big rotating buffer, to spread the cleaning product. The bonnet also has an absorbent pad on the bottom, which absorbs all the dirt while you use it on the carpet. When the pad in question gets dirty, it can easily be replaced with a new one. The cleaning process continues until the pad stops getting dirty.