Blue and yellow make green, and which blue and which yellow decides the green. Painters mix most greens rather than buying them, because a tube green looks artificial in a landscape. The two blues do very different jobs: Phthalo Blue is cool, extremely strong and leans green; Ultramarine Blue is warm, weaker and leans violet.
Bright green or natural green
If your greens are dull, you are probably using Ultramarine. Its red lean brings a little of the third primary into the mix, and that knocks the green back. That’s a problem for a lime, and exactly what you want for a sage.
- Lime, kelly, emerald: Phthalo Blue with a yellow. Lime Green is 19 parts Cadmium Yellow to 1 Phthalo Blue.
- Olive, moss and army green: green knocked back with a little red, its complement, or Ultramarine instead of Phthalo.
- Forest, hunter and bottle green: deepen with more blue and a touch of red. Not black.
- Mint, seafoam and pistachio: light greens in lots of white; a touch of blue makes them cooler.
Phthalo Blue: a speck is enough
Phthalo is one of the strongest pigments in any paint box. Add it to other colours a tiny amount at a time; a dot can take over a whole pile of paint. It also survives white far better than Ultramarine, which is why every pale blue and aqua in the library has Phthalo in it.
Blues: lighter, darker, duller
- Sky, baby and powder blue: blue into a lot of white.
- Navy and midnight: deepen with a touch of orange or red, blue’s complement. Navy Blue is 16 parts Ultramarine, 3 Phthalo Blue, 2 Cadmium Red. Black makes it flat.
- Denim, steel and slate: dull the blue with a little orange or brown, then lighten.
- Periwinkle and cornflower: Ultramarine with a touch of magenta and white.
Teal, turquoise and aqua
Teal is blue with a little yellow, darkened. Start from Phthalo, add yellow until it turns blue-green, then deepen. Turquoise is the same blue-green brighter and lighter; aqua, Tiffany blue and duck egg are turquoise with more white, and duck egg is dulled with a speck of red. Dark teal and petrol blue take more blue and a touch of red.