How does toilet paper hold together (and break down?)

Here’s an everyday mystery to think about next time you're on the loo. How is it that toilet paper stays in sheets when it's dry, and falls apart when it's wet?  

Unlike the rougher, papery toilet paper of the past, modern loo roll feels soft, light, and airy. It rips easily, floats gently, and it’s so light that a box of 48 unbleached bamboo rolls (to pick a random example) is easy to lift and store. The moment it hits water it dissolves so easily that it can be simply flushed away. 

But when you actually use it, toilet paper, like tissues and kitchen rolls, holds together perfectly well. It doesn’t fall apart in your hands and you don’t end up with a little pile of toilet paper dust on your bathroom floor (we hope).

So what’s going on? Is there glue involved? Some kind of technological secret? Magic? 

The science of toilet paper is surprisingly simple and builds on simple chemical processes and hundreds of years of papermaking. When we make Naked Paper we take advantage of the natural qualities of plant fibre; it wants to stick together.    

How toilet paper is made

A lot of people picture paper as tiny fibres stuck together with something sticky that’s been added to the mix, a bit like how pouring egg into a mixture of flour, butter, and sugar will bind everything together to make a cake. We think this is what people are thinking of when they ask us, occasionally, about our glue. 

We do use plant-based adhesives to stick down the ends of our rolls, but that’s not how toilet paper holds together. 

The strength from toilet paper comes from cellulose, the natural material that makes up plants. In the case of Naked Paper, that’s unbleached bamboo (for our bamboo rolls) or the mixture of unbleached plant fibres that went into the recycled packing paper and cardboard we use for our recycled rolls. 

If you zoomed right in to these raw materials, you’d see that they’re made up of long, stringy molecules with lots of natural bonding points on the surface, tiny places where one fibre can latch onto another like little hands reaching out to hold on.

When we make paper, we mix our raw materials with water, making a kind of paper porridge. Those fibre molecules swell and soften up, with the water helping them stick together temporarily, a process called hydrogen bonding. 

When the pulp runs through our papermaking machines, it’s quickly pressed and dried. In just a few seconds, most of the water is gone, and the fibres are forced tightly together. The hydrogen bonds disappear and all that’s left are those little hands, now pushed very close together, and they grab each other directly. 

The cellulose has locked together at the molecular level. 

People didn’t know the science behind this when paper was first developed, but the principle has remained the same for hundreds of years. When you pulp a fibrous cellulose material with water and press it, the dried sheets will hold together with no glue required. 

How does toilet paper stay strong when you use it?

On its own, one of these cellulose bonds isn’t very strong, but there are millions of them in a single sheet of toilet paper, with all the bonds clinging to one another like velcro. 

We help the process along with a bit of natural starch, which is chemically similar to cellulose and gives the fibres a few extra “hooks” to cling onto. If you’re interested you can read the full breakdown of the ingredients we use to make toilet paper (and our kitchen rolls and tissues) here.

After the paper has been pressed and dried each batch is tested to make sure it hits the right strength. Our rolls sit at around 74 N/m when dry, which means they’re sturdy enough to do the job without any unexpected tears.

How does toilet paper dissolve?

So if every sheet of Naked Paper has millions of pairs of bonds holding it together, how does it fall apart in water? 

Well this is the clever bit; those same bonds that give paper strength are simple to undo under the right conditions. And the right conditions just so happen to be found in your loo. 

When toilet paper comes into contact with water the cellulose fibres swell up again, and they stop gripping on to each other so tightly. The sheet loses its structure and begins to break apart into individual fibres.

The flush helps too. The swirling motion of the flush applies a bit of gentle pressure to the loosening tissue, and helps the bonds break apart more quickly. And once toilet paper heads into the sewers, more water, movement, and some friendly microorganisms keep the process going. The toilet paper breaks down into the tiny fibres it’s made from. 

What causes toilet paper blockages? 

That’s how toilet paper holds together, and how it breaks down. While we’re on the topic we’ll tackle why, sometimes, it doesn’t break down, forming blockages. 

By this stage we’ve established what toilet paper needs to break apart, just water and some movement, like a flush, to help the bonds loosen. But problems come in if the sheets don’t have enough movement, or water, around them. 

The most common reason why this would happen is if you use a thick wodge of toilet paper in one go. If you have children or have ever looked after them you might know the kind of quantities we’re talking about. It’s true that toilet paper is designed to dissolve in water, but even the strongest flush can’t take half a roll in one go.   

When lots of toilet paper is wodged together in the bowl, the water can’t easily reach the fibres in the middle. Instead of separating, everything gets bundled into one stubborn lump, and this means trouble for your pipes. 

As with so much in nature, a bit of breathing room makes all the difference.

Strong where it matters, soft where it counts 

That’s the chemistry lesson over. 

Toilet paper holds together thanks to natural cellulose bonds that form as it dries. It breaks down because water loosens those same bonds and lets the fibres drift apart again. Strong in your hand, gone with a flush. 

If you’re interested to learn more about how we make Naked Paper, check out this post about how our toilet paper is dried. And if you want to welcome millions of unbleached cellulose bonds into your own home, we've got just the thing...