Made from synthetic hair, hair extensions can be fun to dye in nontraditional hair colours 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 fibres accept Rit Dye best, but you may be able to dye your synthetic hair depending on the composition of the fibres and how they were treated. A lighter hair colour 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 (60 degrees Celsius). 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.
Test the colour on a few strands of hair that has been cut off to see if the hair can be dyed before you attempt to dye the whole piece. Wait until the hair is completely dry before deciding if it is the correct shade. If you want it darker, repeat the procedure again.