If you notice discoloration on your viscose fabric after using a vinegar solution, take the following steps right away: Thoroughly Rinse  To remove any residual vinegar, rinse the affected area with cold water. Mild Detergent Spot Test  If the discoloration persists, test a mild detergent on a hidden area to see if it helps lift the stain. Seek Professional Advice  If the stain persists, seek the advice of a professional cleaner who specializes in delicate fabrics.