Made from synthetic hair, hair extensions can be fun to dye in nontraditional hair colors for drama. Synthetic hair can be made from various types of material, such as polyester, silk, silicone, monofilament or polyurethane, and not all types can be dyed. Natural fibers accept Rit Dye best, but you may be able to dye your synthetic hair depending on the composition of the fibers and how they were treated. A lighter hair color will be easier to dye than a dark one.
Cover your work surface with a plastic garbage bag that has been cut open, and put on a pair of plastic gloves.
Pour 1 c. liquid Rit Dye into a large bowl. Or, dissolve 1 tsp. powdered Rit Dye into 1/2 c. hot water (140 degrees Fahrenheit). If your tap water doesn't get that hot, bring it to almost a boil on the stove.
Dip a sponge into the dye, and squeeze out the excess. Apply the dye to the synthetic hair in strokes working from the scalp down.
Wait 20 minutes for the Rit Dye to set.
Rinse the hair in cold water. Rinse it very well until the water runs clear, indicating the absence of dye in the hair.
Allow your hair piece to dry naturally. Never attempt to use a hair dryer on synthetic hair.