What makes a colour warm
Warm colours are the reds, oranges, corals and golden yellows, at their brighter and cleaner end. (Once they are dulled down, they become earthy tones.) They feel like sunlight and fire, and in a picture they tend to come forward. A warm object on a cool background looks closer than it is.
Temperature is also relative. A red can be warm (leaning orange, like Cadmium Red) or cool (leaning purple, like Quinacridone Magenta). Knowing which way each tube leans is the key to clean mixes.
Keeping warm colours clean
Warm colours stay bright when every paint in the mix leans warm. Cadmium Red and Cadmium Yellow make a clean orange because neither contains any blue. If a warm mix turns muddy, a cool-leaning paint has usually slipped in. Mixing an orange from Quinacridone Magenta and Lemon Yellow works, but it comes out duller, because each of those leans slightly towards blue.
Using warm colours
- Put warm colours where light hits. Sunlit sides of objects are warmer, and shadows are cooler.
- Use a warm focal point against cooler surroundings to pull the eye.
- A painting that is entirely warm can feel airless. Leave a few cool notes so the warmth reads.