Have you ever noticed that some bars of soap produce enormous, fluffy bubbles almost immediately, while others make a much denser, creamier lather? And then some produce relatively little foam at all.
So what’s going on? Is one soap better than another?
Not necessarily. Personally, I DO prefer abundant lather, and I formulated my soaps to produce it, but the amount and type of lather a soap produces depends on several things, and one of the biggest is what the soap is actually made from.
It all starts with the oils and butters
If you’ve read some of my other Blogtober posts, you’ll know that I make soap by combining oils and butters with sodium hydroxide. During saponification, the fatty acids in those oils and butters are transformed into soap.
Interestingly (to me, anyway), different oils contain different combinations of fatty acids, and those fatty acids produce soaps with different properties. Some are particularly good at creating large bubbles, some contribute to a rich, creamy lather, and others influence how the bar feels during washing.
It’s one of the reasons soapmakers spend so much time developing and tweaking their recipes.
Coconut oil: the bubble maker
Coconut oil is particularly good at helping soap create plenty of bubbles. It’s rich in fatty acids that produce a quick, generous lather, which is one reason it’s so popular in soapmaking. It also produces soap with strong cleansing properties, and there’s the catch.
Use too much coconut oil in a formlua without balancing its cleansing strength, and the finished bar can feel rather drying on the skin. So while coconut oil is a vert useful ingredient, more bubbles don’t automatically mean a better bar.
Olive oil: a different kind of lather
Olive oil behaves quite differently. Soap made predominantly from olive oil tends to produce a less bubbly lather, which can feel almost creamy or slippery rather than wonderfully foamy. Traditional Castile soap, made from olive oil alone, is a good example.
It doesn’t produce the same great clouds of bubbles you’d expect from a coconut-rich soap, but that doesn’t mean it isn’t doing its job. It’s just a different kind of soap.
What about butter?
Ingredients such as shea butter and cocoa butter bring other useful properties to a formulation. They contain fatty acids that can contribute to a firm bar and a more stable, creamy lather. Rather than creating enormous bubbles, they help give the foam a denser, richer feel. Think less bubble bath and more luxurious, creamy lather.
And then there’s castor oil
Castor oil is another ingredient that soapmakers often use in relatively small quantities. It’s particularly useful because its fatty acid composition helps support and stabilise lather. It doesn’t simply create a mountain of bubbles all by itself, but it can help make the bubbles produced by the rest of the formulation more satisfying and longer-lasting. A soapy team player, if you like.
Does more lather mean cleaner skin?
No, and this is where science comes in again. We tend to associate lots of bubbles with lots of cleaning power, partly because we’re so used to heavily foaming washing products.
But the amount of foam isn’t a reliable measure of how well a soap cleans. Soap works because its molecules can help lift oils and dirt from the skin so they can be rinsed away with water.
Bubbles might make the process more enjoyable, but you don’t need huge quantities of them to get clean and soap that produces a fairly modest lather can still wash perfectly effectively.
Why can the same soap sometimes lather differently?
And just to complicate matters further, it’s not only the formla that affects the bubbles. Hard water, for example, contains minerals that react with soap and make it harder to produce lather.
How you use the bar can make a difference too. Rubbing soap onto a wet washcloth or loofah can help build more lather than simply rubbing it between your hands.
Even the amount of water you’re using can change the experience.
So if you take the same bar of soap into two different bathrooms, you might find it behaves slightly differently. Soapmaking chemistry is nothing if not determined to keep us on our toes.
So what’s the perfect amount of lather?
There isn’t one. Some people love big, fluffy bubbles. Others prefer a dense, creamy lather.
For me, the aim when developing a recipe is to find a balance between cleansing, lather, hardness, longevity and how the finished bar feels on your skin.
There’s no point creating the bubbliest soap in the world if it leaves your skin feeling uncomfortable afterwards. And equally, a beautiful formulation isn’t much fun if you have to work at it for ages just to get enough soap onto your hands. It’s all about finding that happy medium.
So next time you’re using a lovely bar of handmade soap, take a moment to notice the lather. Those bubbles aren’t just a happy accident. They’re the result of some quite deliberate choices made long before the soap was poured into its mould.
Who knew washing your hands could involve quite so much chemistry?
Vicki x
