In general, human hair wigs can be dyed using the same process that is used with human hair grown from the scalp. Synthetic wigs require a different process, which typically involves using fabric dye. While synthetic dye does exist, it is usually very expensive and hard to find. Do not try using regular human hair dye on synthetic wigs because it will not hold the color like it would with a human hair wig. MusicalTheatreAudition.com says human hair dye will often drip color down from a synthetic wig. The wig can also turn out a different color than intended or come out blotchy.