One tip for using liquid Rit dye is to heat the water to around 140 degrees Fahrenheit for the deepest color. Another tip is to add 1 tablespoon of laundry detergent to the dye bath to promote an even dye across the entire garment.
Add 1 cup of salt to the dye bath to make the colors more intense for fabrics composed of linen, cotton, rayon or ramie. Add 1 cup of vinegar to the dye bath to make the final color more intense for fabrics composed of nylon, silk or wool. For the best results, soak the fabric in the dye for five minutes before adding the salt and vinegar.
For even dyeing, use half a bottle of Rit liquid in 3 gallons of water for every pound, or approximately 3 yards, of fabric. However, for dark or bright colors, such as dark green, purple, brown or black, use the same amount of water, but double the amount of liquid Rit. Wear rubber or latex gloves when dying with liquid Rit dye, and do not pour the liquid dye directly onto the fabric.
In regards to caring for the dyed fabric, wash the garment by itself two or three times in cold water with detergent containing no bleach. Clean the washing machine with bleach and hot water to keep any remaining color from staining the next load of laundry.