When garments do not have a care label, you must determine the safest method of cleaning for the garment. Following are a few quick tests you can perform to determine the cleanability of a garment.
First, determine the fiber content (ex. cellulose, synthetic, protein, or acetate) of the garment. This is important because knowing whether a fiber loses its strength when wet, whether it is heat-sensitive, or whether it has the potential to shrink will help you make an informed decision about how to clean the item. This can be accomplished either by conducting a burn test or by using acetone to determine if the garment contains acetate fibers.
Look at the fabric construction to determine whether it will be damaged by the agitation of cleaning or finishing. Also check to see if there are any special trim or buttons that may require testing.
To determine if the item can be safely drycleaned, test for colorfastness with drycleaning solvent. To test for colorfastness to wetcleaning or washing, use a neutral detergent. If the dye on the item bleeds to drycleaning solvent, the cleaner may opt to wash the garment instead. If testing with detergent indicates that damage or color loss will occur with this procedure, consult with the customer.
Also, see this post on how to test for colorfastness