Despite its name, commercial dry cleaning is not actually a “dry” process. Clothes are immersed in a solvent, most commonly perchlorethylene (perc), instead of in water. Perc or other similar solvents are effective in the removal of oil and grease-based stains without damaging or shrinking sensitive fabrics, unlike a regular detergents and fabric softeners.
Shirley, Lindsey and Weller, Chanae, "Dry Cleaning" (2010). All Current Publications. Paper 203.