For many years, draperies or curtains have been cleaned using a dry cleaning process, and each time they are cleaned they shrink. Draperies are made from natural fibers in most of the homes we live in. Curtain fabrics are made from rayon or polyester, but 90% are silk and cotton. When these two fibers are exposed to moisture, they shrink.
The reason they must be cleaned in your home is that ceiling treatments cannot be removed. They are permanent and are not meant to be removed. In many cases they are stapled to cornice boards. Draperies are often folded in elaborate patterns that no one will be able to duplicate once they are removed. That is why drapery cleaning assistance is required while cleaning them.
The best way to keep your draperies looking good is to vacuum them periodically, pleat by pleat. However, traces of dust and dirt remain that homeowners may not be able to clean. These residues are the reason you need a professional cleaner. Cooking oil, for example, combined with the aforementioned dust, creates a completely new soil, which will not come out with a simple vacuum.
Professional curtain cleaners, clean curtains with two vacuum cleaners. The first is a backpack HEPA filter that removes most of the dust from the curtains. They then apply a cleaner that suspends the soil. The suspended soil is then removed. The machine is vented to the outside. The machines used by experts have the absolutely correct pressure because they are specifically designed for cleaning drapery.