In this post I am going to talk about the formulation of detergents like face-wash, shampoo, shower gels, bubble bath and so on…
All these detergents are made starting from a family of ingredients: SURFACTANTS.
Surfactants are compounds that lower the surface tension of a liquid and therefore they emulsify the grease and the dirt on our skin and help us to wash it off with the aid of water.
Surfactants can be divided in four groups according to their ionic nature:
– cationic – positive charge when ionized. They are mostly used in conditioners.
– anionic – negative charge when ionized. They are largely used in detergents and shampoos and provide good detergency and lather. In this family we ding: SLS (sodium lauryl sulphate), SLES (sodium laureth sulphate), ammonium lauryl/laureth sulphate, sodium lauroyl sarcosinate, disodium laureth sulfoccinate.
– non-ionic – no charge (unionizable). They are lauryl glucoside, decyl glucoside, coco glucoside, caprylyl/capryl glucoside. These are usually not used in shampoos because they don’t leave a comfortable feeling on the hair (it makes them feel dry) unless they are included in the formulation in small amount (and therefore they work more as foam stabilizers).
– amphoteric – both positive and negative (depending on the pH). These are used a lot in shampoo formulation: specially if combined with SLES they help the shampoo to be thick and they also decrease the irritancy (read this in a relative way 🙂 ). They are for example: cocamidopropyl betaine, lauramidopropyl betaine, coco-betaine, cocamidopropyl oxide.
THE ACTIVE MATTER of a surfactant:
How “strong” do we need our detergent to be? This of course depends to what we aim to make: if we are going to make a bubble bath it will need to have a higher washing ability than a face-wash, which should, on the contrary, be very gentle and delicate. The washing ability of a detergent is determined by its “Active Matter” coefficient: every surfactant has an “active matter coefficient” which is a number in percentage (for example the SLES coefficient is 27%) and this tells us “how much active washing substance there is in our SLES… and in this case it is 27%”. This is because the liquid surfactants which we can easily find sold online are usually made of the real surfactant and water (so the active matter is not 100%). You should find out this number from where you purchase your surfactants (if they are not mentioned on the page, send an e-mail to the supplier).
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)
So now you might be thinking that to make a good shampoo you just need 45% SLES and rest of water and tadaaa… well… NO 😀
It is true that the 45% of SLES plus 55% water would give you a solution with 12.15% Active Matter (45*27(which is the active matter coefficient of SLES):100= 12.15) however there is something very important you still need to know:
In a formulation a single surfactant results more harsh than an equal “active matter %” formulation made with different surfactants.
To make it simple: if you mix surfactants together, you will have a milder results than using the surfactants alone.
A particularly happy mix is SLES with a betaine (usually I have cocamidopropyl betaine) because not only the betaine lowers the harshness of the SLES, but it also thickens the solution.
Generally when formulating you should use:
– anionic or non-ionic surfactant; it is the surfactant which we will add in our detergent at higher %.
– anphoteric surfactant; it will make the first surfactant more mild.
– extra surfactants: these are used in very low percentage and are added to improve the lather or the consistency of the detergent.
To be continued… 😉
[Theory of Formulating a Detergent Part 2]
(Sources)
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Thx I’m new in this field. So I can’t give my opinion.
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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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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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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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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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Good Stuff. Very Good Stuff. Let me read part II, then you can quiz me.
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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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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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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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I don’t remember reading this anywhere on a book. I just figured this out by comparing formulas of products which are sold.
You can reference the blog.
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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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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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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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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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Hello! what would be the active matter of surfactants for a hand wash? thank you for this post!
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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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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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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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