How to formulate a detergent – THEORY pt. 1

How to formulate a detergent

LAB NOTES & SAFETY NOTICE
These are personal experiments for educational use only— not instructions and not for commercial or consumer use. By proceeding, you assume all risks related to safety, testing, and regulatory compliance.
[Full Legal Disclaimer & Safety Requirements]

My Lab Notes: Surfactant Theory & The Chemistry of Cleansing

Hello Hello! 😀

I’m recording my research into surfactants (Surface Active Agents). These are the amphiphilic molecules that make my cleansers work. Their “water-loving” head and “oil-loving” tail are what allow them to lift debris from the skin.

1. The Four Groups (My Personality Map)

Surfactants can be categorized by their electrical charge. It’s the easiest way to predict how they’ll interact with skin and hair:

  • Anionic (-): My “powerhouses” for foam and cleaning (SLES, Sarcosinate).

  • Cationic (+): I use these for conditioning because they “stick” to the negatively charged hair shaft.

  • Non-Ionic (0): Usually mild stabilizers (Glucosides).

  • Amphoteric (+/-): My “buffers.” I’ve found these are essential for reducing the irritancy of the Anionics (Betaine).

2. The ASM Calculation (Active Matter)

I’ve documented a common trap: raw surfactants are rarely 100% pure. They are usually solutions.

  • The ASM Coefficient: Always check my supplier’s sheet. For instance, if my SLES is 27% ASM, I have to calculate my formula based on that “pure” percentage, not the total weight of the liquid.

My Target ASM Hierarchy:

Based on my trials, I’ve set these “strength targets” for my formulas:

  • Intimate Wash: ~5% ASM

  • Face Wash: <10% ASM

  • Shampoo: 10% – 15% ASM

  • Shower Gel: 18% – 20% ASM

  • Bubble Bath: 20% – 25% ASM

3. The Synergy Discovery

One of the most important things I’ve recorded is that synergy reduces irritancy.
Using 12% ASM of a single surfactant is much harsher than a 12% blend of three different types. I now always use a “Trio” (Primary + Buffer + Aesthetic Booster) to keep the skin barrier happy.

Self note: It’s important that I keep checking the Technical Data Sheets. Sometimes the same ingredient can vary between 27% and 30% ASM depending on the batch!

It’s all about layering the charges correctly to get a product that cleans without being aggressive.

26 thoughts on “How to formulate a detergent – THEORY pt. 1”

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  2. Thank you for sharing your expertise and detailed explanation for a newbie to understand. I had just formulated a liquid hand wash which turned out “liquid’ as you have explained, going my wits about what went wrong, then I found you! Such a blessing! Now, I will try this approach using SLES, SLS, and Coco Betaine. I really hope I don’t have to add salt. In the event, I guess, I’ll have to start at 1% is this correct?

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    1. Don’t use SLES and SLS together.
      Use SLES and Betaine. Why wouldn’t you add salt? It is not such a bad ingredient, specially for a hand wash 🙂
      And yes, 1% usually suffices. Of course it also depends how thick you want it to be! 🙂

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  3. Thanks for sharing!

    Could you use Sls and cocamidopropyl betaine or Slsa and cocamidopropyl betaine together?

    Sorry but I am new to this and trying to formulate a bubble bar recipe that uses cocamidopropyl betaine that would act as a foam booster but also help the Sls become milder. I have both SLS and SLSA to hand and want to try them both out.

    Any advice would be appreciated!

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    1. Hi, are you talking about SLES? Cause I dunno what SLSA is.
      However yes, I have many recipes with SLES and cocamidopropyl betaine. Check the shampoos recipes 🙂 they work as body detergents as well 🙂
      This combination is a very simple and effective one.
      🙂

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  4. I’ve heard Disodium Lauryl Sulfosuccinate is more gentle, is it still pretty harsh if used in a low percent without an anphoteric surfactant? Thank you!

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    1. It is very gentle indeed, yet I always tend to pair surfactants together, however in this case I have seen it in some commercial products used as the sole surfactant.
      I would suggest you to try different combinations, do a little experimeting and find out what feels more delicate to you! 🙂

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  5. Hello,

    I am working on a project and I need to reference the % active ingredients that you have listed here:

    “Generally the active matter of surfactant we want in our detergent depending on its aim is this:
    – Face wash – lower than 10%
    – detergent for intimate use – around 5%
    – shampoo – between 10% and 15%
    – shower gel – between 18% and 20%
    – bubble bath – between 20% and 25% (this is because the bubble bath should go directly in the water while the shower gel is supposed to be rubbed directly on the skin)”

    The only problem is I don’t think a blog will be allowed as a reference! Can you point me to where you got this information?

    Thanks!

    Claudia

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  6. I need to make a body wash for low level atopia/ itchiness. I used cocoa and decyl glucoside 1:2 in 5 and 10% respectively, which makes my skin dry. Now Im being offered sodium lauroyl glutamate and/or sodium cocoyl glutamate as hypoalergenic, but I dont know how should I use these, I mean percentages and combinations with other detergents. I would be grateful for any help.

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    1. If it is a skin condition you should first contact a dermatologist. What you can formulate is simply a delicate body wash which won’t solve a skin condition but that might not make it worse.
      You add the suggested concentration of use on the MSDS of the ingredient. However, you can add ingredients to make a detergent milder: a 1-2% of oil for example, an hydrating ingredient (glycerin, for example).
      These are cheap ingredients that can really make a detergent more mild.
      Hope you get to make the body wash of your dreams 🙂

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  7. Hi I was wondering about how do you calculate for different size bottles? Like what size bottles are these measurements referring to?

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    1. These measurements are for 100%… Which means that if you turn the percentages in grams you end up with 100 grams of product.
      If you need 500 grams, you simply multiply every measurement per 5.
      100 grams clearly don’t translate to precisely 100 ml, unless you bottle pure water.

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  8. Hello! what would be the active matter of surfactants for a hand wash? thank you for this post!

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    1. Hi Gabriela, I would say around 15% but it actually all depends what kind of a hand wash it is. Please don’t take there percentages as A FIXED RULE 🙂 they are just indicative of what could be a good concentration… But you can formulate differently as well 🙂

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  9. How informative – a brilliant post, thank you!!!! What AM shall I consider when making foaming hand wash? (used in a foamer / foaming pump bottle) I guess less that for face wash?

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    1. Hi Magdalena. Hmmmm for a hand wash it is usually more than for a face wash but the tricky thing for a foaming hand wash is getting the right consistency and the right surfs actually. What I mean is that, while usually you want to formulate something that is “thick enough”, for a detergent to actually be able to work in a foaming bottle you need a quite thin/liquid formula. I have never formulated one to be honest but I have thought about trying sometime 🙂 so I cannot help you with this formulation yet unfortunately, cause I have no experience with it. I can tell you though how I would try: of course avoid any thickening surf, then make a formula that you like and incrementally thin it out until it works for you. You could start by adding 5 or 10% of water (this is just a test so no problem with having to add the preservative yet). Once you get the right “liquidness” you can work backwords and figure out what AM it is and all the percentages you actually have in your formula now that you have thinned it out. This is at least how I would go for it.

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