Why Is My Soap Crumbling When I Cut It?

There’s nothing quite as disappointing as making a beautiful batch of soap, waiting patiently for it to be ready, and then watching it crumble when you cut it.

You’re left wondering, What happened?

Sometimes the answer is your soap. Sometimes it’s the timing. Sometimes it’s the way you’re cutting it. And occasionally, your poor cutting wire gets the blame when it really isn’t the culprit at all.

The good news is that once you know what to look for, crumbling soap is usually something you can work out and improve.

First, check when you are cutting your soap

One of the biggest causes of crumbling is cutting the soap at the wrong stage.

If your soap is still too soft, the loaf can drag against the wire, distort or tear rather than giving you a clean cut.

At the other end of the scale, if the soap has become very hard and dry, it can become brittle and crack as the wire passes through.

There isn’t one magic cutting time that works for every recipe. Different oils, water amounts, additives, fragrances and even the temperature of your workspace can all affect how quickly your soap sets.

You want the soap to be firm enough to hold its shape, while still having enough flexibility to cut cleanly.

And this is one of those things that comes with experience. After a while, you start to recognise the feel of the loaf.

Is your soap recipe contributing to the problem?

Your recipe can have a big influence on how your soap behaves when you cut it.

Some recipes naturally produce a softer bar, while others become quite hard relatively quickly.

A high proportion of soft oils, changes to your water or lye concentration, certain additives and some fragrance oils can all change the way a loaf sets.

If you suddenly have a batch that is crumbling when previous batches of the same recipe cut beautifully, have a look back at what changed.

Did you use a different fragrance?

Did you change an oil?

Was your water amount different?

Did the soap behave differently in the mould?

Sometimes the clues are there before you even pick up the cutter.

Your cutting wire matters too

The cutting wire has a fairly important job. It needs to pass through the soap cleanly and evenly.

A wire that is loose, damaged or unsuitable can drag through the soap rather than making a smooth cut.

A good quality, properly tensioned cutting wire should do the work without requiring you to force it through the loaf.

It’s worth checking your wire regularly, especially if you cut soap frequently. They are small details, but small details can make a surprisingly big difference when you are trying to get those lovely clean edges.

Don't forget your cutting technique

This one is easy to overlook.

When cutting by hand, it can be tempting to push, pull or saw your way through a difficult loaf. Unfortunately, that can make the problem worse.

Try a smooth, steady movement and let the wire do the cutting.

If you find yourself having to force the wire through the soap, stop and have a look at what is happening. The soap may be too hard, the wire may need attention, or the cutter may not be giving the loaf enough support.

A stable cutter also helps keep the loaf in position while you cut, which is particularly useful when you're working with larger loaves.

What if your soap is already crumbling?

Don't panic. We have all had batches that didn't behave the way we expected. 😊

If the soap is otherwise perfectly usable, there are still plenty of ways to make use of it.

You can:

• Trim away rough edges once the soap has hardened.

• Use the smaller pieces for embeds in another batch.

• Turn the pieces into soap confetti or curls.

• Keep the pieces for testing or personal use.

• Consider rebatching if the recipe and soap are suitable for it.

And sometimes, the best thing you can do is make a note of what happened.

Soap making is a bit like that. You learn as much from the batches that don't behave as expected as you do from the beautiful ones.

Can the right soap cutter help?

A good cutter can't fix a soap recipe that isn't behaving properly, but it can make the cutting process much easier and more consistent.

A cutter that holds the loaf securely and keeps the wire straight and properly tensioned gives you a much better chance of getting clean, even cuts.

This becomes especially important as your batches get larger.

If you're making a loaf occasionally, an adjustable single bar cutter may be all you need. If you're producing several loaves at a time, a multi-bar or slab cutter can make a considerable difference to the amount of time and effort involved.

At Crafted Surprise, we make our soap cutters for exactly this reason. We've been soap makers ourselves, so we know how frustrating it is when you've spent all that time making a batch and then struggle to get the finish you're after.

A little patience goes a long way

If your soap is crumbling, don't immediately assume you've done something terribly wrong.

Take a look at the recipe, the timing, the soap itself, your wire and the way you're cutting.

Usually, one of those things will give you a clue.

And remember, every soap maker has had a batch that didn't quite go according to plan. That's part of learning the craft.

Keep making, keep experimenting and, eventually, you'll get to know exactly when your soap is ready for that first cut.

Happy soap making! ❤️