What is stone paper, and how is it actually made?

Stone paper is not made from trees. It is about 80 percent ground limestone, the same calcium carbonate that is in a marble worktop or a spoonful of baking soda, held together by around 20 percent plastic [1]. No pulp. No process water, no chlorine bleach, no wood. Ink from an ordinary ballpoint or a pencil takes to it fine, rain runs off because there is no fibre to soak it up, and tearing is a lot harder than with the paper in an ordinary notebook. It is not waterproof the way a dry bag is, and it is not plastic free, and any brand telling you both of those at once is hoping you skip the small print.

That is the short version. Most pages explaining stone paper stop about there, add a line about saving trees, and leave out exactly the things you want to know before buying. This one keeps going.

What stone paper is made of

Two raw materials, in a ratio of 80 to 20 by weight:

• Calcium carbonate, about 80 percent. Limestone, quarried and ground to a powder.
• HDPE, about 20 percent. The plastic that binds every grain into a sheet.

The first is calcium carbonate, ground to a fine powder. It comes from limestone, one of the most common rocks on earth, quarried and then milled. It is white by itself. The second is HDPE, high-density polyethylene, the same plastic as in milk bottles and bottle caps. That is the binder. Without it the limestone powder is just powder and you have no sheet.

Now the part marketing usually keeps vague. You often read that the plastic is recycled. Sometimes it is, sometimes not, and it depends entirely on the manufacturer. In our sheets the HDPE is virgin plastic, because recycled HDPE is hard to buy consistently at the purity a thin film needs. We would rather say that plainly than print a claim we cannot honour every batch. The recycled HDPE in our chain is in the shipping boxes, not in the pages. If another brand says recycled plastic without saying which batch, that is a fair question to ask.

How stone paper is made

The process is clever, and it looks nothing like a paper mill.

The limestone powder is mixed with heated HDPE until the plastic coats every grain and the whole mass sticks together. That mixture is then extruded and blown into a thin film, the way a glassblower thins a bubble by blowing into it. As the film travels up a tall tower it cools, and by the time it reaches the top it has set at the required thickness. Then it is drawn down and rolled up. That is all. No tree is felled, no water is needed to stir fibres into a slurry because there is no fibre, and no bleach or optical brightener is needed to make it white, because ground limestone already is. The mill our sheet comes from is Cradle to Cradle certified and produces without waste water [2].

The material was first produced in Taiwan in the late nineties, and most of the world's production still comes from there and from China. A young material with an ancient raw ingredient.

How it writes and how it holds up

This is where the real trade-offs sit, and almost nobody writes them down.

Ink behaves differently. Because the surface absorbs nothing, a gel or fountain pen takes longer to dry, so a fast left hand smudges a wet line. An ordinary ballpoint or a pencil is the sweet spot, and pencil takes to that slightly chalky surface beautifully. The sheet is denser and a little heavier than wood paper of the same thickness. You notice that across a whole notebook, not page to page.

And then the rain. Because there is no fibre to absorb water, the sheet does not cockle, pulp or go transparent when it gets wet, and pencil or ballpoint stays where you put it. Wipe dry and keep writing. That is water resistant, not a waterproofing rating, and the difference matters: submerging it finds the limit. Where exactly that limit sits we have not measured, and we are not going to invent a number for it. As soon as the proof arrives we will run that test and put the result here.

Is stone paper really the greener choice?

That depends what you compare it with, and the answer is not a glossy percentage.

Against paper from virgin wood pulp the production story is real and checkable: no trees felled, no process water in forming the sheet, no bleach chemistry [2].

What we do not do is attach a CO2 percentage. We have since run our own footprint, and the result is more honest than comfortable: in production stone paper sits roughly thirty percent below wood paper, but across the full life cycle it is about a draw, because the plastic holding the sheet together is fossil and counts when incinerated, where paper is scored as biogenic and sits at zero. The full calculation, with sources and with the places it wobbles, is in we calculated our own notebook's carbon footprint.

You will see 94 percent on some notebook pages. That comes from the MOYU life cycle assessment, which compares one erasable notebook with fifteen single-use ones over three years [3]. That gain sits mostly in reuse, not in the material, and therefore does not apply to a permanent notebook like ours.

The downsides are just as real. Limestone still has to be quarried and that costs energy. Because of the plastic, stone paper is NOT biodegradable, NOT compostable and NOT plastic free, three claims you should never see sitting next to it.

On recycling the story is actually more positive than you would think. In practical tests HDPE has been recycled at least ten times while keeping its properties [4], and calcium carbonate does not degrade at all; it is already a common filler in recycled plastic [5]. Set that against a paper fibre, which averages four loops in Europe [6]. What is missing is not chemistry but collection: Dutch plastics collection is for packaging, so a worn-out notebook does not formally belong there. That is why you are welcome to send it back to us. More on that in our piece on whether stone paper is recyclable.

Stone paper, ordinary paper and coated paper compared

Stone paper is not the only way to make a notebook cope with rain. The three side by side:

The best-known outdoor brand, Rite in the Rain, coats ordinary wood paper so water beads off. The difference is where the water resistance comes from: for them it is a layer on a fibre sheet, for stone paper it is a property of the sheet itself, so there is no coating that can wear off over time. Neither is better in general. They are two answers to the same wet problem.

Frequently asked questions

Is stone paper waterproof? It is water resistant, not waterproof. Rain, splashes and damp hands leave it alone, because there is no fibre to take them up. It is not made for submersion and it is not diving gear.

Can you write on it with an ordinary pen? Yes. Ballpoint and pencil are ideal. Gel and fountain ink work too, but dry more slowly because the surface absorbs nothing.

Is stone paper biodegradable? No. Under prolonged UV it becomes brittle and powders, but in a dark landfill it stays put, like most plastics and in practice most buried wood paper too.

Does stone paper have a lower carbon footprint than paper? Not demonstrably. In production yes, across the full life cycle about level. We ran the numbers ourselves and the result is in our article on it.

Is stone paper recyclable? As a material, better than paper: HDPE manages at least ten loops [4] and calcium carbonate does not degrade [5]. What is missing is a collection stream. Details in our separate article.

Does it work in the cold? Yes, and that is where it is at its best. It stays supple in frost, where damp wood paper would tear along the fold.

Who invented it? It was first produced in Taiwan in the late nineties, and most stone paper still comes from that region.

The short version

Stone paper is ground limestone and a little plastic, blown into a sheet that ignores rain and skips the tree, the process water and the bleach that wood paper needs. You write on it with the pen you already own. The environmental gain is in what doesn't happen: no felling, no bleach, no process water. On carbon it is not a clear conscience but roughly a draw, and we checked that ourselves rather than leaving it unsaid.

So for your next wet morning outdoors: which would you rather have, notes that survive the weather or the recycling debate? How our stone paper notebook does the first is on the product page. No tree, no bleach, no process water, and here is what that does and does not mean in numbers.

References

1. Stone paper composition, about 80 percent calcium carbonate and 20 percent HDPE, and classification under plastic code 2.
2. MOYU life cycle assessment: production without process water, Cradle to Cradle certified mill.
3. The same assessment: 6 kg CO2 for fifteen wood pulp notebooks against 0.37 kg for one erasable stone paper notebook over three years, that is 94 percent.
4. Practical tests showing HDPE can be recycled at least ten times, published via Plastics Today.
5. Pebble Printing Group, Stone Paper FAQ: calcium carbonate as a filler in recycled plastics.
6. Cepi, Circular Economy: in Europe during 2024 every fibre completed on average four cycles of recycling and use.