While many dyes are made specifically for natural fibers, with the right dye, you can dye fiber blends, including cotton-polyester mix fabrics or garments. Polyester blend fabrics will be more difficult to dye and results may be more unpredictable than an all-natural fiber, but blends with at least 50 to 60 percent cotton can be dyed with some success. Color results may be somewhat lighter than with an all-natural fiber, and the best results require a white or light-colored base fabric.
Choose the same brand and color of fabric dye in both a polyester and a cotton formulation, as well as a color intensifier to boost the color.
Fill a large stainless steel or enamel pot with enough water to cover the fabric or garment, but do not put the fabric in the pot. Place the pot on the stove over high heat. Add the two dyes and color intensifier to the pot, mixing well with a stainless steel spoon.
Place the fabric in the pot and bring the dye pot to a rolling boil, maintaining high heat.
Stir in 1 cup of table salt to the dye mix and fabric. Continue stirring for approximately half-hour. Stir constantly for the most even dye result.
Remove the fabric from the dye bath and allow to cool completely. Wash by hand with a mild detergent and allow to dry completely.
Fabrics with less than 40 percent polyester may be dyed with a single dye formulated for cotton fabrics; however, the fabric will achieve a lighter color or tint, rather than a rich color.
Try dyeing a sample first to make certain you are happy with the results.
While blended fabrics can be dyed, you will achieve better results and find the dyeing process more successful if you opt for 100 percent cotton or other natural fiber garments or fabrics.
If dyeing garments, keep in mind that thread, zippers or elastic may not dye.