When painting, the best colours can be the ones you create on your own. Though black watercolour paints can be bought in the store, different shades of black can be easily created by mixing the three primary colours of paint. Mixing your own black watercolour paint requires only a few materials you likely already have in your home.
Decide what shade of black you want. The shade of black that you want will determine which colours you should choose to mix together. For a soft black, use an aureolin yellow, a rose madder genuine red, and a colbalt blue. For a medium black, use new gamboge yellow, permanent rose, and French ultra marine blue. For a strong and bold black, use winsor yellow, permanent alizarin crimson, and winsor blue.
Place a paper plate on a flat surface. You will use this to mix the paint on. You may also use newspaper or any covering that you do not mind being covered in paint.
Mix a paintbrush with a little bit of water into each individual red, yellow, and blue colour. Add each colour to the paper plate, adding more in equal measure. For more black paint, use more of each colour in equal part. For less, use less paint.
Mix the colours together using the paint brush gently. Mix until the three primary colours are no longer discernible and have become one fluid shade of black.