What thickness of paper stops felt tips bleeding through?
Paper from about 120gsm up stops most felt tips going through to the other side, and 140gsm has room for a child who presses hard. Printer paper is 80gsm, and plenty of colouring books aren't far off that. That's why the ink so often goes through to the back of the page.
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Those figures come from a home test: my kids coloured test pages on paper from 120gsm to 160gsm.
Why do felt tips bleed through colouring books?
A felt tip puts down wet ink. The ink soaks into the paper, and if the paper is thin it goes all the way through. Pencil and crayon leave colour on the surface instead, so they don't go through.
In every off-the-shelf colouring book I've bought, the ink has gone through the page, from cheap supermarket felt tips to the well-known brands.
What gsm paper stops felt tips going through?
Cartridge paper at 120gsm or more stops most felt tips. It's the paper sketchbooks are made from. The thicker the paper, the further the ink has to travel before it reaches the other side, so the weight does most of the work.
Paper is sold by weight rather than thickness. The number on the pack is grams per square metre, gsm for short. The bigger the number, the thicker the paper. The weights for printer paper, booklet pages and card come from a UK printer's paper weight guide, and the feel is what each one's like in the house.
| Paper | Weight | What it feels like | Felt tips go through? |
|---|---|---|---|
| Printer paper | 80gsm | Thin, flops if you hold it by one corner | Yes |
| Heavier paper | 110 to 120gsm | Noticeably stiffer, still bends | At 120gsm most don't, but not if they press hard |
| A leaflet, a printed booklet | 130 to 170gsm | Holds its shape, doesn't crease when you turn it | Most don't, this is the range that works |
| Cartridge paper | 140gsm | Matt, with an even texture, nothing like printer paper | Most don't, even when they press hard |
| Greetings card | 250 to 300gsm | Card, stands up on its own | Hardly any, but this is cover weight, too stiff for pages |
When 120gsm isn't enough
120gsm is about where most ink stops going through, but there isn't much to spare at that weight.
The pen and the hand
A fat pen puts down a lot more ink than a thin one, and a child who goes over the same patch four times puts down more still. If your child uses fat pens and presses hard, you want 140gsm.
Printed on both sides
In a thin book printed on both sides, the ink that goes through lands on the next picture.
A book printed on one side only isn't safe either, which is what usually catches people out. The ink still goes through to the back of the sheet. If the book gets closed before it dries, that back is pressed against the next page and marks it. Some books give you a spare sheet to slip in between, which is a faff and the first thing to get lost.
Does the surface matter as well as the weight?
Yes, it changes how the colour looks on the front of the page.
Matt paper takes the colour evenly, where you put it. On shiny paper the ink slides about and pools, and it sits there wet instead of drying into the page. That's what makes a magazine page hopeless to colour on.
The surface also has to be the same all the way across, or the colour goes streaky in one corner.
What our books are printed on, and why
Toodaloo's personalised colouring books are printed on 140gsm cartridge paper, on both sides of every page. In my test, 160gsm was starting to feel stiff when my kids turned the pages, so I stopped at 140gsm. It's still thick enough to stop most felt tips going through, which matters more with a picture on the back. It's also vegan, which sounds a strange thing to say about paper until you find out not all paper is.
Which photos to choose is a different question, and the photos that make the best colouring pages covers that.
How do you check a colouring book's paper before you buy it?
120gsm is the lowest I'd buy, or 140gsm if the pages are printed both sides.
Look for the number
The number is usually on the back cover, or in the description if you're buying online. A book on decent paper tends to say so on the cover.
Feel it
If a book comes with a spare sheet to slip in between, that usually means the paper's thin. Failing that, take a sheet of printer paper in with you and feel the two together. You want the book page to be noticeably thicker.
Holding a page up to the light doesn't tell you much. On 140gsm you can still see the picture on the back against a window, but most felt tips stay on the front.
If the book you've already got is thin
If the ink's going through a book you already have, the paper is the paper and you can't change it now. Pencils and crayons still work on it, because they sit on the surface instead of soaking in. A sheet of card behind the page stops the ink reaching the picture behind, though the back of the page they're colouring will still get marked.
Questions parents ask
- Do washable felt tips bleed less?
- Not reliably. Washable means the ink comes off skin, tables and clothes. It doesn't tell you how far the ink goes into the paper. The weight of the paper matters far more than the pen. On 140gsm most children's felt tips stay on the front, washable or not.
- Can I print colouring pages at home on thicker paper?
- Usually, yes. A pack of 120 or 140gsm cartridge paper from a stationer is the weight that works in a colouring book. Check the maximum paper weight in your printer's manual first, every printer has a different limit. Paper that's too heavy won't feed properly.
Colouring books on 140gsm paper
20 of your own photos, drawn as colouring pages and printed on 140gsm both sides. You see every page before you pay.
Any photos to start. Nothing is charged until you approve every page.