The only way to make black by colour blending is to combine the main hues. One of three combinations—yellow and purple, orange and blue, or green and red—or two colours alone can be used to accomplish this.
The shade of black produced by colour mixing is frequently unsatisfactory. Results may differ depending on the type and colour of pigment used. Trial and error would be required to blend colours, adding more or less pigment as needed to achieve a colour that is deemed satisfactory.