Polyester fabrics are impossible to dye without the use of dispersion dyes. Dispersion dyes sink deep into the fibres and bond with the synthetic materials. RIT dyes are dispersion dyes, but they often have difficulty adhering to synthetic fibres such as polyester. The reason that the dyes do not stick to polyester is that the polyester must be heated to a high temperature to accept new colours. Dye all polyester fabrics in a large pot on the stove to ensure the fabric accepts the dye evenly.
Weigh the fabric. Fill the pot with three gallons of water per pound of fabric. Heat the water to about 71.1 to 93.3 degrees C.
Dissolve the powdered dye into the hot water. Use 1 per cent dye for light colours, 2 to 3 per cent for medium colours and 4 to 5 per cent for deep colours.
Soak the polyester fabric in warm water until drenched.
Place the fabric inside the dye bath. Add 6 per cent of dye developer to the liquid. Add enough acetic acid to the bath to bring the acidity to 6. Use pH test strips to determine the acidity of the dye bath.
Bring the liquid to a boil. Stir the polyester fabric inside the dye bath every two or three minutes. Continue to boil the fabric for 30 minutes.
Remove the polyester fabric from the dye bath and rinse with hot water. Continue to rinse the fabric until the water runs clear. Wash the fabric with washing powder to remove any remaining traces of dye.
When working with dyes, always take any necessary precautions, such as wearing protective gloves. Never use materials for cooking or eating that have been used for dyeing.