Fill the bucket with hot water and 2 cups of soda ash, a potassium salt. Soak the skirt in the soda ash solution for at least 12 hours. Wring the skirt out after the 12 hours.
Place the skirt onto a flat board and mix the dye in the bucket. Black dye requires a hot water mix and an extra quantity of dye to make it jet black. For a single skirt, use 1 gallon of near-boiling (just under) water and 2 cups of dye. Fill the squirt bottle out of the bucket when the dye is mixed.
Dip the sponge brush into the dye and lift it out parallel to the ground. A sponge brush holds the liquid in when parallel to the ground and drips when at angles.
Coat the entire skirt with dye using the sponge brush. Let the dye soak in for at least 20 minutes. Go back over the skirt with another coat of dye and let it set for another 20 minutes.
Go over the skirt and squirt dye from the bottle on any missed spots or areas that show bleed or fade. Cover the dyed skirt for 24 hours with a plastic sheet.
Hand rinse the skirt after 24 hours and fill a washing machine on the small load setting with 2 to 3 tbsp. of synthrapol detergent. Synthrapol detergent is a special chemical detergent that neutralizes excess fiber-reactive dye when in water.
Run the skirt through a full wash and two rinses. Remove and dry as needed.