Rayon has become one of the most popular fabrics available due to its comfort and absorbency. However, rayon is very sensitive to water, and this presents a number of problems. One is in the dyes that are commonly used with rayon. Most of them are not colorfast and can be altered by moisture.
Since rayon garments commonly have sizing to help them hold a certain shape, there is another problem with this fabric. Many sizings are water-soluble, so washing the garment in water can distort it causing it to become unwearable.
As a result of these factors, dry cleaning is recommended for many types of rayon garments.