A classic mistake! In lighting, black is the absence of light. In paint, black is a mix of all the primary colours, thus depending on the proportions of each colour, you create different shades. But because we have a limited range of colours, we describe anything darker than X as 'black', however you can thus have a black with lots of blue, lots of red or lots of yellow. Black is primarily made up from Blue and Red base colours, thus towards the red end will be warmer, and towards the blue end will be cooler.