What makes soap lather?


For most people, soap is simply a necessity to use every day without thinking twice about it. However, there are some interesting facts, such as what makes soap lather that you might not know but sell. 

Lather in soap is created when air bubbles interact in a liquid. They create surface tension-free films that are made from soap molecules and water. You can increase lather in soap by adding certain oils, sugar, honey, or a lathering agent. 

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A lot of people enjoy using soap because it makes their skin feel clean. However, what many people do not know is what actually causes soap to create that squeaky-clean feeling is not the amount of lather it makes.

What is lather in soap?

“Lather” is a term that refers to the foam or froth that detergent creates when rubbed or stirred in water. This effect allows you to determine which areas are clean and which ones are not, even if soap doesn’t work that way. It is mostly an aesthetic effect that acts as a guide.

Water and soap create lather due to the tension created between both elements as they mix together. Then, small bubbles start appearing when the air begins displacing water molecules, releasing surface tension in the process. Thus, we can say that lather is actually small bubbles “packed” forcefully together.

But there are more elements such as coconut or castor oil, or even sugar in some cases that help create this effect. 

Most of us have the impression that homemade soap doesn’t lather that much compared to commercial soap. While handcrafted soap DOES lather, it’s important to take into account that not all soap recipes are equal. 

Some of them may have ingredients that encourage it, while others may suppress it. Therefore, we have tons of different soaps that lather differently.

Is soap lather important?

Soap lather is present in all types of soaps at a higher or lower degree, and although it only contributes to an aesthetic effect, we can’t say whether it is important or not. It’s a subjective question that depends on your preferences.

If you try to search this topic around the web, you’ll likely find information about how “soap lather makes you cleaner.” However, soap does NOT work that way, and the only reason why lather is present is because of consumer demand. There is no real research that proves that lather has an actual cleaning effect. 

We like to see that something is working, and the only way we have to ensure that the soap we use is truly cleaning us is the lather. With that being said, is lather a really important aspect of soap? It probably isn’t, but it has become an essential part of it under society’s standards, and we wouldn’t have it any other way.

Does soap have to lather to work?

Soap doesn’t need to lather to have its cleaning effect, but many people don’t really know this. In fact, the only reason why it is present in soap, shampoos, and other products is because of consumer demand.

Let’s take a look at how soap works.

We all have been taught that oil and water don’t mix, but that’s different when it comes to soap. Soap gets mixed with water and oil as you rub it through your skin. That’s because soap molecules have two different ends: hydrophilic (attracts water) and hydrophobic (attracts grease and oil).

This way, oil and dirt get mixed and are removed from your skin when you rinse it away with water. This process is no different when there is no lather.

So the next time your soap lathers, know that it’s not the “lather” that actually has the cleaning effect – what truly has a cleaning effect is the combination of water, soap, and oil. So, even if you don’t see any lather, no worries, it is still doing its job!

Why does some soap not lather?

There are many reasons why some soap doesn’t lather. This can be due to the surface area, certain ingredients, or even because of the water.

Small soap bars

Firstly, small soap bars don’t produce too much lather because of surface area. With bigger soap bars, you have a larger area available, creating lather more easily. 

Presence of certain ingredients and agents

If you enjoy making soap or buy it from someone else, you should know that certain ingredients can make your soap not produce lather. For instance:

  • Soaps made from a single oil will likely produce less lather. For instance, castile soap is made with one-hundred percent olive oil, and while it’s excellent for sensitive skin, it will not produce as much lather as we are used to.
  • Hard, creamy soap bars are less likely to produce water, mostly because they’re made of a single fat. 
  • A soap high in superfat (also known as lye deficit) can be good if you want the oils present in the recipe to have a greater effect on your skin. However, high superfat levels also translate into less lather.
  • If you’ve used too much butter (shea, cocoa), that may be good for your skin, but not so much if you’d like your soap to create lather. Butters is known to diminish the lather on soaps as it happens with single-coil soaps.
  • Hard water will decrease the lather of your soap. Hard water contains certain metallic ions, like magnesium or iron, which will reduce this effect. This isn’t directly related to your soap, so you can try and soften the water and see if it still has the same problem.

What makes soap lather?

To explain what makes soap lather, we must first consider that when this reaction happens, there are two layers of detergent molecules with a fine layer of water molecules between them. These three layers create the “lather” in soap, which is nothing more than air bubbles. 

This “sandwich” of detergent and water molecules is very thin and lightweight, which means that when you agitate it in water, it will react with the water and the detergent’s components, producing lather in the process.

Gradually, the water molecules start coming out of the bubbles until there’s nothing left, which results in the bubble exploding.

As mentioned in the section above, different agents are responsible for making soap lather. However, it’s totally normal for natural ingredients not to create enough lather we are used to with commercial products. 

All the soap, shampoo, and detergent you see in the stores create “bubbles” thanks to chemicals explicitly meant to create foam.

Does castor oil make soap lather?

Yes, castor oil helps you make your soap lather. It is one of the best ingredients available for this purpose, as the effects are remarkable. Besides having an exceptional lather effect, castor oil is also known for having humectant properties. Thus, adding it to your soap can be pretty beneficial if you want smoother skin and more bubbles while you’re taking a bath.

However, please note that castor oil is only recommended for cold process soap, and it’s recommended to use it at about 10%.

What oil makes soap lather?

There are a few options out there that create a better lather. These are mostly hard oils and fats; however, please remember that you may have a different experience based on your recipe and technique.

Coconut oil

If you want to get started with something easy, coconut oil is the best option but also the most accessible. However, keep in mind that you’ll need to keep it balanced as it may make your skin feel too dry. It is highly recommended to mix coconut oil with other moisturizing oils.

Palm oil

Palm oil is also helpful when it comes to creating a lather. It is solid under normal circumstances, but it becomes liquid and easier to blend with other oils once you melt it. 

Almond oil

Almond oil is a soft oil, but it is one of the few non-hard oils that creates a fantastic lather. It may not be as high as with other oils, but if you add moderate amounts to your recipe, you will get bather lather when the soap is ready.

Beef tallow

Beef tallow is animal fat. Although most people avoid using animal fat when making soap, this is one of the best options you have if you want to create more lather. It’s a very hard fat that creates later when the superfat or lye discount is around five percent or less.

Lard

Lard is another animal fat. In the past, lard was the main ingredient used to create soap in the USA and Europe. It isn’t used that much since plant oils became much more common, but it works exceptionally well to produce lather when mixed with a small amount of sugar.

What ingredients make soap lather?

Besides the oils, more ingredients will help you get a high lathering soap. Here we describe some of the most common options available.

Sugar

Using sugar in your recipe can help you get better lather once the soap is ready. However, you can’t just add any amount of sugar. One teaspoon per base oils pound is more than enough.

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Also, you must add sugar when the lye solution is still hot and then stir it until the sugar has dissolved completely.

Sugar is the easiest option to make your soap lather more, but adding too much can cause other problems, like overheating, heat tunnels, and many others. Soap is a complicated ingredient to work with if you don’t use it correctly.

Some alternatives to sugar include the following:

  • Fruit juice at 1 oz per pound of base oils
  • Apple cider vinegar

These alternatives can help you reduce the risk of the problems that sugar may cause in your recipe.

Honey

Honey is another very common ingredient you can use to get more lather out of your soap. However, similar to sugar, honey is also quite tricky to use and can ruin your recipe if you don’t use it appropriately.

Like sugar, you should only use one teaspoon per base oils pound. But this is not the tricky part – the real problem shows itself when it’s time to add it to the lye solution. The best way to add honey is by letting the lye water cool for a little while, then add the honey. 

Adding honey to the lye solution while it is too hot may cause it to burn the sugar within the honey. Furthermore, you shouldn’t add any other sweet substance if you’re using honey, as it will make your recipe too vulnerable to overheating.

Cocoa & shea butter

If you’re making soap using different oils, adding some shea or cocoa butter to the recipe can help you stabilize the lather levels. These kinds of butter will not help you create more lather, but they will stabilize it and make it easier to obtain.

Shea butter works best if you keep it at 3-5% of all the oils used in the soap. On the other hand, cocoa butter is better at 5-15%.

Other options

You can try other things, such as limiting superfat, using certain oils, and many others. Many soap artisans use different ingredients and techniques to make soap with good lather.

Can I add sugar to liquid soap?

Yes, you can use sugar or honey in your liquid soap recipe. The result would be transparent and bubbly soap. It is recommended to add it after the saponification process. Still, take into account the using too much sugar in your soap. Make sure you’re using the appropriate measurements based on the number of ingredients you’re using.

Does shea butter help soap lather?

Shea butter is known to help with stability, but it doesn’t contribute to the soap lather. It is indeed helpful to make it more accessible, but overall, it is not known to help soap produce more lather. That’s why it is recommended to keep the percentages low – this way, you can prevent your soap from cracking, from feeling brittle, or even waxy.

Conclusion

Lather in soap is quite a tricky subject. Since we’ve been using the same techniques for centuries, there isn’t any actual research that determines what ingredients are better to create lather. Lather in soap does not affect its effectiveness, so your soap is still good even if you don’t see a lot of bubbles.

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