Ammonium Lauryl Sulfate vs. Sodium Laureth Sulfate: A Formulator’s Practical Guide

For more than five years, we’ve been the person brands, that’s why entrepreneurs calls us if they made a wrong choice with their surfactant. This is not usually just picking an impressive ingredients, instead you need to choose the one that will matches the product requirements. And in cleansing products, some people have confusion between the Ammonium Lauryl Sulfate (ALS) and Sodium Laureth Sulfate (SLES). We really see the confusions, as some of our clients was being confused about the price, performance, and the market needs. So, what we’re doing to avoid this is we explain how these molecular actually affect the real products. And in this article, we will show you how ALS and SLES really works, and how your choices will affects the final outcome or product.

Understanding the Basics: What are ALS and SLES?

Let’s make it simple, ALS and SLES are both surfactant. That means they are the main ingredients in cleansing and creating foam in products, like shampoos, body washes, and facial cleansers. And their role is to remove the oil and dirt to the skin and hair and allows them to be easily rinsed with water.

The Ammonium Lauryl Sulfate (ALS):

They are strong and have more direct option. It is comes from lauryl alcohol. It is known in creating thick, and creamy lather that is powerful when being used.

The Sodium Laureth Sulfate (SLES):

It starts with the same lauryl alcohol but goes through an extra step called ethoxylation, which added ethylene oxide chains. SLES is known for its voluminous, copious foam that is gentle on the skin when used.

In choosing, you need to know where it will be use, as each of them can works best for different product requirements. For example, we worked with a brand creating a men’s shampoo marketed as “strong but gentle.” They avoided SLES because of things they read online and choose ALS instead. And this choice can caused problems during testing.

Client Chat Screenshot 1 (The Problem):

We’ve received a message from one of our client and says, "We’ve got our first prototype based on ALS. The lather feels amazing, really luxurious. But our test panel with sensitive scalps is reporting a tight, squeaky-clean feeling, and a few mentioned slight redness. We’re marketing ‘gentle strength, this isn’t it. What did we miss?". So, we replied to them, that they’re experiencing the direct impact of ALS's excellent cleansing power, and that that squeaky clean is because of over-stripping. We also mentioned that will look further into it. And we can clearly see that the issue isn’t with the lather, instead it’s how the ingredient interacted with the skin.

The Molecular Difference: Why Size Matters for Your Skin

The main difference between ALS and SLES is molecule size and the structure. ALS has smaller molecule, and because it’s small, it can remove oil very quickly and effectively. And this makes it a strong cleanser, but it can remove too much of the skin’s natural oils, and this might causes the squeaky clean feeling. While, SLES has a more larger molecule. It cleans more gently, removes the dirt and oil, but it’s less likely to disturb the skin’s natural oil, and this is why most people experience less irritation with SLES.

Our first client asked us, "So SLES is just universally gentler?", and we answered not always. Because the gentleness of the product will depends on the formula. But as a main cleansing ingredient, SLES usually has a lower risk of irritation because of its larger size.

Irritation Levels: Breaking Down the "Harshness" Scale

We can hear the words harsh every time, but in formulation, it can be measured. With the help of industry tests and human skin testing consistently, we can show that SLES is less irritating than ALS.

ALS ranks higher on the irritation scale. With its strong oil removing power, it works well for deep-cleansing products, but it can be too much for sensitive skin, facial products, or daily-use formulas unless it was carefully adjusted.

SLES is more milder, that’s why it’s commonly used in products marketed as “gentle,” “baby,” or “for sensitive skin.” However, mild does not mean harmless. A poorly designed formula with a high level of SLES and no soothing or moisturizing ingredients can still irritate the skin. In addition, ALS can feel gentle when it’s balanced with the right ingredients.

This is the reason why we adjusted course with the shampoo brand, we didn’t immediately remove ALS. But, we tried first on improving the formula by adding cocamidopropyl betaine and conditioning agents to soften its effect. With this it the formula became harder to manage and more expensive. So we compared it directly with an SLES-based version.

The Ethoxylation Process: How SLES Becomes Gentler

Ethoxylation is the process that transforms lauryl alcohol into laureth alcohol before it’s sulfated. And by adding those ethylene oxide units there are two critical things happened:

1. It heps in increasing the molecule's water solubility. The larger head group can hydrates more easily, which help to reduce the molecule's interaction with the skin proteins.

2.  It also changes its Critical Micelle Concentration. This is always hard to explain that the CMC is the concentration at which surfactant molecules start forming micelles. This means, that the concentration in a bottle, there are more individual ALS molecules roaming free and interacting with your skin, while more SLES molecules are already have milder micelles.

Client Chat Screenshot 2 (The Solution):

For this second client, they have sent us message about this, "Think of ethoxylation as putting a soft bumper on the surfactant. ALS is a direct hit. SLES has padding. For your goal of daily gentle strength, that padding lets us achieve great cleansing without the backlash. Let's prototype your formula with SLES as the primary, keep the cocamidopropyl betaine for foam boosting and mildness, and see what your panel says." And then the client agreed to test it. This changes doesn’t mean about removing the hash chemical, but instead its having a great too for the job.

Formula Stability: Why Chemists Choose One Over the Other

How well a product performs also depends on how stable it can be. This is where the difference between ammonium (ALS) and sodium (SLES) really matters.

ALS (Ammonium Salt)

The ammonium makes the ALS to be dissolved easily in water, but it works well in a lower temperatures. However, its biggest disadvantage is it is very sensitive to ph. If the formula becomes more alkaline, it might release ammonia, which can cause bad smells. And because of this, ALS cannot be used with ingredients that needed higher ph.

SLES ( Sodium Salt )

The SLES is much more stable, as it can works well across a wide pH range. And this gives chemists more flexibility, they can add acids, use alkaline thickeners, or combine it with many other ingredients without problems. This what SLES makes widely used in more complex products.

For our client, this was the deciding factor, because their future plans included adding anti-dandruff ingredients and cooling agents, which often need specific pH levels. That’s why choosing SLES made the formula more stable and allowed the products for future improvements.

The 1,4-Dioxane Concern: SLES Safety Explained Simply

We can always talks about SLES without talking about this issue. That’s why we always explained it to our clients, as we know that we can build trust if we will be having a clear and transparent communication.

The 1,4-Dioxane is not an ingredient, beause it is a tiny leftover substance that was formed during manufacturing. So, here’s we always explain, based on our real experienced:

1. It can be removed. The manufacturers can remove 1,4-dioxane using a simple cleaning step that is called the vacuum stripping, and this helps to bring down the levels that is considered safe by regulators like the FDA and the EU.

2. Supplier choice is critical. We only use SLES from suppliers who provide official test results and shows very low 1,4-dioxane levels. Many of them meet strict standards such as ECOCERT/COSMOS . This is not optional, as it is one of the important things that we need to considered. 

3. The problem is the impurity, not SLES itself. When it is properly purified, SLES can be safe to used. With this it help the industry to understand and solved this kind of issues. 

If this will be ignored, it can caused a lot of problems. That’s why asking for a proof is  necessary. When a shampoo client asked about it, we shared some lab certificates from our trusted supplier, and this help them to solved the problems.

Client Chat Screenshot 3 (Result):

Client (after 8 weeks):

This is the feedback we have received from our client, they’ve mentioned that the SLES formulas performed well in testing. And the people with sensitive scalps really loves it, with no dryness, great foam, and no irritation. Also, the users who wants to have a deep clean said that they felt strong but not that harsh. And their lab team also found it more easy to work with. And they also thank us for focusing more on innovating ou products to meet their specific needs.

The Final Lather

The question is which better? The Ammonium Lauryl Sulfate (ALS) or Sodium Laureth Sulfate (SLES)? The answer is we can’t say either of them, as they have different purpose or usage:

We use ALS when we need very strong cleansing, and acidic formula like shampoo, body wash for oily skin, or when we need its specific solubility benefits. While, we use SLES for 70% of our cleansing formulas. Because it is mild, creates rich foam, stays stable, and works well in daily-use products.

The real lesson with this isn’t about who and what is better, but it is with good formulation and choosing the right tool for the job. And by understanding how the ingredients work, checking on how the skin responds, and making sure that every ingredients are working well all together. With this process it can ensure that you’ll create products that meets the people’s needs and earn more trust.