The tulle netting used for making tutus and petticoats, as well as other types of nylon nets, can be a difficult fabric to dye. However, the same acid dyes used to dye wool and other animal fibres will dye nylon netting. The results may not be as bright as they would on protein fibres, but they will be colour-fast. Some manufacturers make acid dyes specifically for dyeing nylon, which may give you a truer colour.
Fill a sink with as much hot water as you need to cover the net. Add 1/2 tsp of highly-concentrated liquid detergent for each pound of net. Soak the net for 30 minutes.
Add 1/2 tsp of dye powder to a measuring cup for each pound of net. Pour in 1 cup of boiling water for light shades or 2 cups of boiling water for dark shades. Stir constantly with a plastic spoon until all the dye powder is dissolved.
Boil 3 1/2 gallons of water in a large metal pot. Pour in the dye mixture and stir for 30 seconds to mix.
Add 1 tsp of highly-concentrated detergent and 1 tbsp of citric acid crystals to the dye bath for every 1/2 tsp of dye powder you used. Stir for 30 seconds or until all the crystals are dissolved.
Squeeze any excess water out of the net and immerse it in the dye bath. Reduce the heat to a simmer and leave the net in the dye bath for at least 30 minutes, stirring every five to 10 minutes. Darker colours may take up to one hour.
Turn off the heat and allow the dye bath to cool down to room temperature. Hand-wash the net in cold water, rinse it until the water runs clear and hang it to dry.
Use a detergent made to work with dye for best results. These industrial detergents are available from sellers of acid and fibre-reactive dyes.