Things You'll Need
Burnt Umber paint
Acrylic paint can be used to create colors so you don't need to have a large variety of colors on hand. If you wanted to create a flat black color rather than purchasing it, you can use your ultramarine blue and burnt umber acrylic paints. A flat black means that the black paint is devoid of gloss or shine. This creates a very dark background without the subtle hues and tones that a glossy paint would have.
Collect your painting items, including your canvas, paint brush and palette. Squeeze a dab of ultramarine blue and burnt umber on your canvas.
Mix the burnt umber with ultramarine blue to create a black. If you want a flat black, add equal parts of both paints to create a dull black without any shine.
Add more burnt umber to the mix if the black looks colder or has a blue tint. Add more ultramarine to the mix if the black appears to be too warm. Creating an equal balance of the two colors will remove the subtle hues that make the paint appear glossy.
Add a little bit of water to the paint to thin out the paint and flatten the color further.