Wash your red clothing
Wash your red clothing before coloring it in order to remove things o the fabric that are not good for the dying process. Use a good quality washing soap or power with low chemical quantity. Incase if the clothing is already clean, then just wet it in warm water.
Note: Make sure to avoid the chemical fabric softeners as they can contain harsh ingredients that can make the fabric harder for the dye to fix.
Get ready to dye
Put on disposable or rubber gloves and smock in order to get ready for dying.
Prepare your dye bath
Select a large metal bucket or sink, enough for your clothing to move easily. Pour in at least 3 gallons of hot water and place it on the stove over middling heat. Add in the black-dye according to the proportions pointed out on the package. Take a large wooden spoon and stir until the dye mixture is even, forming a required black dye bath.
Add red clothing and simmer
Smooth out wrinkles of your pre-wet red clothing and add it to the boiling black dye bath, simmering it thoroughly. Stir it continuously for 20 to 30 minutes, changing the direction of stirring in all directions.
Remove the bucket from stove
Once the desired black color is achieved, turn your stove off and remove the metal bucket from the heat. Set the bucket aside for some time and let it cool to be handled.
Take out the black clothing from dye bath
Once the dye bath is cool enough to handle, carefully take out the black clothing from it.
Rinse the fabric with warm water
Now, rinse the dyed fabric with warm water. Make sure to gradually decrease the temperature of the water, and carry on rinsing until the water runs clear.
Wash it with mild detergent
Place the black fabric in the washing machine containing warm water with mild detergent. Turn the washing machine on and wash the black fabric for a few minutes in order to remove the possible remaining dye.
Pull out the black clothing
Carefully remove the black clothing from washing machine and rinse thoroughly in cool water until water runs clear.
Hang it up to dry
Hang your dyed black fabric to dry it properly. Press it once, dry and hang it in your wardrobe.