How to mix acrylic paint colours for paint by numbers

Every OutlineArt colour key comes with a mixing recipe for each paint number, written in parts of eight basic acrylic paints. This guide shows you how to read those recipes and mix colours (colors) that match the swatches. There's also help for when a mix comes out wrong.

The eight paints you need

Every recipe uses only these eight, so any basic student acrylic set that has them will do.

• White
• Black
• Red
• Yellow
• Blue
• Burnt sienna
• Green
• Magenta

Brands differ. One maker's yellow is warmer than another's, and blues vary a lot. That's normal. Treat each recipe as a starting point and finish by eye against the swatch.

How to read a recipe

Take 3 Green + 2 White + 1 Blue. That means three parts green, two parts white and one part blue. A part can be any amount you can repeat, like a drop, a pea-sized blob or a small scoop on a palette knife. Keep the parts the same size and you get the same colour every time. For a big area, just double it to 6 + 4 + 2.

Here are a few recipes from the example on the home page.

Mixing step by step

Start with the lightest paint in the recipe and add the darker ones a little at a time. It takes far more white to lighten a dark mix than it takes dark paint to darken a light one, so going the other way just wastes paint.

Go easy on black and blue. They're strong, and a small amount changes the whole mix. The recipes already allow for that, which is why black often shows up as just one part.

Mix until there are no streaks left. A palette knife works best, but an old brush will do. Then test it. Paint a dab next to the swatch on your printed colour key and let it dry, because acrylic dries a little darker than it looks when wet.

Mix enough for every area with that number. Getting the exact same colour a second time is hard. Keep any leftovers in a small airtight pot, or cover the palette with cling film between sessions.

When a mix doesn't match

If it's too dark, add white a little at a time. White also makes colours paler and cooler, so a warm colour might need a touch of yellow or burnt sienna afterwards.

If it's too bright, add a tiny bit of its opposite on the colour wheel. Red and green dull each other down, and so do blue and orange, or yellow and purple. A touch of burnt sienna works too.

Did your yellow turn green? That's the black. Black darkens yellow into olive, so use burnt sienna to darken yellows instead. To warm a colour up, add yellow or red. To cool it down, add blue.

Don't chase a perfect match. Screens and printers show colour slightly differently anyway. What matters most is how each colour sits next to its neighbours, and if every colour is a little warm, the painting still looks right.

Skin, fur and other tricky colours

Skin tones usually start from white, yellow and burnt sienna, with a touch of red for warmth. Mix one middle tone first. Then make the lighter and darker versions from it, so they belong together.

The browns and greys in fur come mostly from burnt sienna, black and white. Greys made from only black and white can look cold, and a little burnt sienna warms them up.

Greens in nature are rarely the green straight from the tube. The recipes often soften them with burnt sienna, yellow or magenta, like colour 9 in the table above.

New to paint by numbers? The guide for kids has tips for getting started, and how to print it covers paper and printer settings.