Take your garments containing viscose to your local dry cleaner to have them cleaned. The dry-cleaning process uses dry solvents to clean the fabric without any risk of shrinking or loss of color.
Do not wear a garment containing viscose if there is any chance that you will encounter bad weather. If you are caught in the rain, the garment may shrink after drying.
Use a home dry-cleaning system with your clothes dryer. Place viscose garments into the dry-cleaning bag and zip it closed. Place the bag in the dryer on tumble (low heat) for 30 minutes. Hang the garment after dry cleaning to avoid wrinkles.