--- title: "Paper chromatography for kids: the colours inside black" description: "A drop of water splits washable black marker into blue, pink and yellow. How paper chromatography works and how to do it with coffee filters." source_name: "Game Tailors" source_url: "https://extreemtekenen.nl/en/experiments/paper-chromatography/" site_home: "https://extreemtekenen.nl/" source_description: "The drawing app where the paper is real. No ads, no accounts, no data collected." locale: "en" legal: - "Game Tailors · Schieweg 15Y-40, 2627 AN Delft (NL)" - "KvK 92437702 · VAT NL866044474B01" - "info@gametailors.com · +31 6 4227 5919" copyright: "© 2026 Game Tailors" published_at: "2026-10-24T05:05:13.233Z" modified_at: "2026-10-24T05:05:13.233Z" --- # Paper chromatography for kids: the colours inside black ## Black ink is hiding other colours Washable black marker is a mix of dyes. Put water on a dot and the water creeps outward through the paper, carrying each dye at its own speed, so the black splits into rings of blue, pink and yellow. [Play in your browser]()[Do it for real](<#for-real>) - Ages 5\+ - 20 minutes - Low mess ![Painted illustration of paper strips and a coffee filter in glasses of water, where black marker dots have spread into blue, pink and yellow bands, watched by the painter.]() ## Quick facts Age 5 to 10 \(younger with help\) Time About 20 minutes Mess Low: a little water and ink Adult needed Only to help cut and hang the strips You need Washable black felt-tip, coffee filters or kitchen paper, a glass of water \(almost free\) On screen / for real Both ## In Extreme Drawing Pick the **Marker** in the drawing bar, choose **Black** and make a fat dot. Then pick **Water** on the Bathroom tab, choose **Drops** and let one drop fall right on the dot. The drop soaks out through the paper fibres and takes the ink with it. As it dries you see a bright cyan-blue ring at the water's edge, a pink band halfway and a yellow-orange centre, the way washable black marker does on real paper. None of the dye disappears: it has only been sorted. It works because a marker's dyes cling to the paper fibres, each by its own amount: the blue lets go most easily and travels furthest, the pink less, and the yellow hardly moves. Food colouring and ink drops don't cling, so they spread with the water as one colour. Try a drop of food colouring next to your marker dot and compare. More to try: other marker colours \(which ones split?\), a row of dots along a line, or a marker drawing on paper that's already wet. Crayon and coloured pencil don't run at all: their wax turns the water away. [Play in your browser]() ![Painted illustration of the painter brushing a rainbow watercolour that bleeds into wet paper, with crayons, markers, a paint box and a child's rainbow drawing.]() ## Do it for real: coffee-filter chromatography **You need** - A washable black felt-tip \(water-based, not permanent\) - White coffee filters, kitchen paper or blotting paper - Scissors and a pencil - A glass or jar with a little water - Sticky tape, or a clothes peg - Other washable colours to compare \(brown, green and purple are good\) 1. Cut a stripCut a strip of coffee filter about 3 cm wide and a bit longer than your glass is tall. 2. Mark the startDraw a pencil line 2 cm from the bottom. Pencil doesn't run, so it won't spoil the test. Make a fat marker dot on the line. 3. Add a little waterPour about 1 cm of water into the glass. The water must stay below the dot. 4. Hang the stripTape the top of the strip to a pencil laid across the glass, so the bottom just dips into the water and the dot stays above it. 5. Watch the colours climbOver 5 to 10 minutes the water creeps up and the colours pull apart. Take the strip out before the water reaches the top. 6. Dry and compareLay the strip flat to dry. Which colour went highest? Try different brands of black side by side. 7. The circle versionLike the app: put a dot in the middle of a round coffee filter on a plate and drip water onto the dot, one drop at a time. The colours spread out in rings. Tips, safety and clean-up - Use washable felt-tips. Permanent markers don't move with water, and the solvents that do move them are not for children. - Keep the dot above the water line, or the ink just washes out into the glass. - Wet ink stains: protect the table with a plate or a tray and wash hands afterwards. - A grown-up helps with the scissors for younger children. ![Painted illustration of paper strips and a coffee filter in glasses of water, where black marker dots have spread into blue, pink and yellow bands, watched by the painter.]() ## Why it works **For kids:** black ink is really a few colours mixed together. Water pulls each colour along the paper, but some colours hold on to the paper more tightly than others, so they get left behind and the colours spread out. **For grown-ups:** this is chromatography. The paper's cellulose fibres are the stationary phase and water is the mobile phase, drawn along by capillary action. Each dye divides its time between dissolving in the moving water and sticking to the fibres; a dye that sticks less travels further \(it has a higher Rf value\). Black washable inks are blends of dyes, often blue, red or magenta and yellow, chosen together to absorb all visible light. Separation needs the dyes to differ. In the game the three marker dyes move at 1, 0.3 and 0.05 times the water's speed. When the speeds were closer together, the colours smeared into each other and only a pale blue ring showed, just as dyes that are too alike blur together on real paper. ## Try next: predict, then test ### Same black, different brands? Do two black markers from different brands split into the same colours? ### What hides in brown or green? Guess the colours first, then test. Is yellow hiding in green? ### Which paper is fastest? Coffee filter, kitchen paper or printer paper: which one lets the water climb quickest? ### Salt water instead? Does a pinch of salt in the water change how far the colours go? ## For teachers Paper chromatography fits KS2 Year 5 "properties and changes of materials" as an enquiry into mixtures and separating \(chromatography itself is named later, at KS3\), and NGSS 5-PS1-3 \(identifying materials by their properties\). Drop water on a marker dot on the whiteboard, ask what colours will appear, then hand out strips. [Ideas for teachers]() ## Questions about paper chromatography What is paper chromatography for kids? It is a way of sorting a mixture of colours with paper and water. The water carries each colour along the paper at a different speed, so they end up in separate bands. Why does black marker turn blue, pink and yellow? Black washable ink is made by mixing several dyes. The blue usually travels furthest, the pink less and the yellow least, though every brand mixes its black a little differently. Which markers work for chromatography? Washable, water-based felt-tips. Permanent markers don't move with water. What paper is best for chromatography? White coffee filters, kitchen paper or blotting paper. Printer paper works but slowly, because it is dense and coated. Why did my colours not separate? Usually the dot was under the water line, the marker was permanent, or the strip touched the side of the glass. Try again with the dot above the water. ## More colour science ![Painted illustration of the painter touching a dish of milk with a soapy cotton bud while red, blue, yellow and green food colouring swirls outwards.]() ### [Magic milk]() Food colouring rushes away from a drop of soap. ![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.]() ### [Red cabbage pH indicator]() A purple juice that turns pink, blue and green. ![Painted illustration of the painter brushing blue watercolour over paper, revealing a white crayon fish and bubbles.]() ### [Crayon resist]() Why wax keeps water and paint away: the secret white crayon message. ## Split a black dot on screen One marker dot, one drop of water, three colours. Then try your own markers on a coffee filter. [Play in your browser]()[All experiments]()