How do you mix burnt sienna?

To mix burnt sienna, start with a base of raw sienna or yellow ochre for a warmer tone. Add a small amount of red, such as cadmium red or alizarin crimson, to deepen the color. For a darker shade, incorporate a tiny bit of black or ultramarine blue, but do so gradually to avoid overpowering the mix. Adjust the proportions to achieve your desired hue and intensity.