Royal Blue is a bright, medium blue. Its a perfect primary color and makes great tie-dyed shirts for first graders. Rit Dye Royal Blue Powder Dye helps you liven up your wardrobe, make truly original gifts for family and friends, and redecorate your home. It can be safely used to color almost all fabrics, as well as wood, wicker, paper and plastic. Dark or bright colors may require double dyeing. Not recommended for 100% polyester, acrylic, or fabrics with special finishes, rubber backing, cold water wash, or labeled dry clean only.