Blue and red combine to make purple. However, mixing blue and red paint does not necessarily yield a vivid purple because paints have different pigments in them.
The best types of paints to mix to get purple are blues with no yellow, green or red, and reds with no yellow. White paint mixed with the original paint helps bring out the other pigments in the paint. For example, if white paint mixed with blue yields a greenish blue, then there is yellow or green pigment in the paint, and it is not suitable for making a rich purple. Similarly, if white paint mixed with red yields an orange rather than pink red, the red paint is not suitable for making a rich purple.
Purple is considered a cool color that inspires images of the sky and water. Cool colors like purple, blue and green are visually calming and soothing and make small rooms appear larger.