Yes, you can shrink rayon.
More Info: Many rayon fabrics are notorious for extreme shrinkage if not dry-cleaned. The amount of durability that a garment will have towards shrinkage will depend largely on which type of rayon the garment is made from and what types of treatments, such as sizing, are added to the fabric.
How Do You Shrink Rayon?
Rayon typically shrinks if it is machine washed, unless it is part of a blended fabric in which the rayon makes up less than 30 percent. Most rayon garments are labeled dry clean only. Some rayon fabrics have been treated with special finishes to make them washable. While this form of rayon is less susceptible to shrinkage, it typically bears a care tag advising the owner to wash it by hand only. Machine washing greatly weakens the fibers even in treated rayon. Though a washable rayon garment may not shrink if placed in a washing machine, its life is shortened.
How to Prevent Rayon from Shrinking?
You can prevent rayon from shrinking by hand washing the garment. Hand washing rayon in cold to lukewarm water will gently clean the fabric with no unnecessary tumbling and agitation. Use of detergent made specifically for hand washing will mildly rid the garment of dirt and grime without the concentrated chemicals of laundry detergents. After rinsing off the soap, shake out the article of clothing and either drape over a clothes drying rack or hang on a padded hanger. Avoid wringing or stretching the fabric while it is being washed and dried. Another way to prevent rayon from shrinking is to take it to a dry cleaner.
“Rayon: Caring for Your Fabric.” Sedgwick County Research and Extension Office. N.p., n.d. Web. 27 Oct. 2011. <http://www.sedgwick.ksu.edu>.
“Fiber Characteristics – Rayon .” FabricLink | Fabric University. N.p., n.d. Web. 31 Oct. 2011. http://www.fabriclink.com/university/rayon.cfm