Extreme Drawing

Dyeing eggs with red cabbage: a natural Easter dye

Easter

Blue eggs from a purple cabbage

Simmer red cabbage, let white eggs soak in the cooled purple juice for a few hours, and they come out a soft sky blue. The dye in red cabbage changes colour with acids and alkalis: pink with vinegar, blue-green with baking soda.

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  • Ages 5+
  • With an adult
  • Overnight soak
Painted illustration of the painter lifting a sky-blue egg out of a jar of red cabbage juice, with jars of dye, a basket of coloured eggs and a red cabbage.
Age
5 to 10
Time
45 min, plus a few hours or overnight
Mess
Medium: the juice stains
Adult needed
Yes, for the knife and the hot pan
You need
Red cabbage, white eggs, vinegar, baking soda
On screen / for real
The colours on screen; the eggs for real

In Extreme Drawing: the colours first

There are no whole eggs to dye in the app (an egg dropped on the paper cracks open). What it does show is the colour chemistry, on paper.

Tap Dip in red cabbage juice on the Time tab and the whole sheet comes out purple. Draw some egg shapes, then paint inside them with Vinegar or Secret ink (lemon juice) from the Science tab: they turn pink and red. Baking soda or dish soap turn it blue to green. Bleach turns it yellow, then destroys the colour.

Two egg tricks the app does have: crack an egg and paint Red cabbage juice over the egg white, and it turns blue, because egg white is alkaline. Drop vinegar on the bits of shell and they slowly fizz away.

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Painted illustration of the painter pouring purple red cabbage juice into a row of glasses that go from pink through purple and blue to green, with a lemon and baking soda.

Do it for real

Dye eggs with red cabbage

You need (for 6 eggs):

  • half a red cabbage (about 500 g)

  • 1 litre of water

  • 6 white eggs, hard-boiled and cooled

  • white vinegar

  • baking soda (bicarbonate of soda)

  • 3 glass jars or mugs, a sieve, a spoon

  • cotton buds or a small brush

  • kitchen paper and an old tray

  1. Make the juice (adult)

    An adult chops the cabbage and simmers it in the water for about 20 minutes, until the water is deep purple. Sieve it and let it cool completely.

  2. Make three colours

    Pour the juice into three jars. Leave one purple. Stir a tablespoon of vinegar into the second (it goes pink). Stir a pinch of baking soda into the third (it goes blue-green).

  3. Predict

    Before the eggs go in: what colour will each egg be? Write it down.

  4. Soak the eggs

    Lower two eggs into each jar with a spoon. Put the jars in the fridge for a few hours, or overnight for a deeper colour.

  5. Lift and dry

    Spoon them out onto kitchen paper and let them dry without rubbing. White eggs usually come out blue, whatever jar they were in.

  6. Shift the colour

    Dab a little vinegar on part of a dyed egg with a cotton bud, and baking-soda water on another part. Watch the colour shift, then compare with your predictions.
Painted illustration of the painter, goggles on his beret, studying a bottle foaming over in stripes, with red cabbage juice in pink and green glasses and fizzing baking soda.

Why it works

For kids: Red cabbage has a purple colour inside that changes when it meets something sour (an acid) or something soapy and bitter (an alkali). Eggshell is made of chalk, which is a bit like baking soda, so the colour turns blue on it.

For grown-ups: The pigment is an anthocyanin, a natural pH indicator: red to pink below about pH 4, purple near neutral, blue around pH 8 and green above about pH 9 (yellow in strong alkali or bleach). Eggshell is calcium carbonate, a base, so where the dye touches the shell its local pH is higher than in the jar, which is why white eggs come out blue even from a slightly acidic bath. Vinegar also dissolves a little of the shell (it fizzes, giving off carbon dioxide), which can help the dye take, but a long soak in strong vinegar softens the shell.

Try next

Brown eggs

Dye a brown egg next to a white one. Brown plus blue makes… what colour?

Kitchen test

Add drops of juice to lemon juice, milk, soapy water and fizzy water. Which are acids?

Patterns

Wrap an elastic band or stick a leaf on an egg before it soaks. What stays white?

For teachers

Red cabbage juice as an indicator fits acids and alkalis in upper primary and lower secondary science, and the colour of the eggs is a good puzzle: the juice was pink, so why is the egg blue? Our red cabbage indicator page has the full experiment.

Red cabbage pH indicatorFor teachers

What colour do red cabbage eggs turn?

White eggs usually turn a soft sky blue, deeper the longer they soak. Brown eggs tend to come out greenish.

Do you need vinegar to dye eggs with red cabbage?

No, but many people add a little. It turns the juice pinker and etches the shell slightly, which can help the colour take. The eggs still come out blue.

How long should eggs sit in red cabbage dye?

At least a few hours in the fridge; overnight gives the deepest blue.

Are red cabbage dyed eggs safe to eat?

Yes, if they were hard-boiled, kept in the fridge the whole time and eaten within a few days.

More colour chemistry

See the colours change on the screen

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