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why are Na surfactants so crummy?
After spending years messing with SLS/SLES/CAPB I gave up and for quite some time now have been very happy with our ammonium-based shampoos. Excellent flash foam, lots of small bubble foam, great sensorials.
I decided to use up the remaining stocks of sodium based surfactants just to get rid of them so I made this body wash:
water 46.5%
SLS 15%
SLES 25%
CAPB 5%
Gel Network 4% (as discussed previously)
glycerin 3%
citric acid 0.2%
fragrance 1%
Potassium sorbate 0.3%The CAPB at 5% was optimum for thickness but the end result was only marginally acceptable for that.
Results:
Flash foam: very poor. Takes a while to get foam generated.
Total foam: marginally acceptable. Creamy. No tight-bubble foam like I get with ammonium salts. Roughly double the amount needed as compared with ammonium surfactants.If you don’t agree with me that Na is markedly inferior to NH, please quote me a simple example formula that uses SLS/SLES/CAPB that in your opinion demonstrates its suitability.
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24 Replies
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What your formula looks like expressed in active percentages?
Assuming SLS is 98% pure powder (we’ll call it 100% for ease of calculations)
SLES is only 70% active (Texapon N70 gel or so)15% SLS powder =15% active SLS
25% SLES gel = 17.5% active SLES
That’s total 32.5% active alkyl sulfates
Ain’t that too much? Why not 9-12 total actives?
(I even succeeded in making a low surfactant, mild hand soap with only 5% active SLES and it did properly thicken with CAPB, Coco DEA/MEA, salt)This article says that most professional formulators choose a 3:7 SLS:SLES ratio
https://www.happi.com/contents/view_features/2009-09-02/the-formulation-basics-for-personal-cleansers
From the percentages above, your formula equals
4.61 : 5.39 SLS:SLES
Way too much SLS as compared to SLES, and way too much overall surfactants as previously mentioned.Is 5% active CAPB?
Or 5% as-supplied CAPB?CAPB is better used at 1/3 (active %) of alkyl sulfates
So if you lower your total SLS+SLES to, say 9%
you’ll need 3% active CAPB
since CAPB is usually supplied as only 30% active,
you’ll need 3% / 0.30 = 10% as-supplied CAPB solution.
Similarly, if you have 38% pure CAPB solution: 3% / 0.38 = 7.89% as-supplied CAPB solution.Why not some Cocamide DEA/MEA/Oleamide too?
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It’s all liquid surfactants and I have no idea what the A/S is like because the supplier doesn’t tell me… the whole point is not to say “ah but by adding this it could be better”, but that changing the given combination for ALS/ALES gives a massively improved result. Even with 45% total surfactants the Na combination is still just “adequate”.
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I believe you’re comparing oranges to (bad) apples
Even though we don’t know the exact composition to propietary Ammonium surfactant blends,
I don’t think they are anything like the formula that you posted.Probably both: overall surfactant concentrations are lower, and their ratios are improved.
For a fair comparison you can try:
3% SLS powder ( = 3% active SLS)
10% Texapon N70 gel ( = 7% active SLES, thus keeping 3:7 ratio, and 10% overall main surfactant concentration)
10% CAPB solution ( = 3 % active CAPB)
1-1.5% Cocamide DEA/MEA/Oleamide
some salt to thicken
and compare that to propietary Ammonium surfactant blends. -
It’s not a blend, it is just ALS/ALES/CAPB by comparison. I also noticed that if I replace the SLS with ALS it is markedly better. The raw mats sold here are either BASF or Lubrizol, I can’t tell which. Powders and gels are not available, just the liquid forms like Texapon N5 or N5G and N70 which is probably what I have here. I’m deliberately excluding the blend because it contains other components too.
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Even for single surfactants, switching brands can make a huge difference in concentrations
If I’m not mistaken
Texapon N70 = SLES 70% (I wouldn’t call that liquid, it’s so thick that I call it a gel)
Texapon N5 = SLES 25%
Texapon N5G = SLES 28-30%
so it’s crucial to know which one are you using, for proper comparison.Still, thanks to reading your posts, when I get my formulas fine-tuned, I’ll try switching to Ammonium surfactants to see if they make a noticeable difference in an already improved formula.
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It’s not N70 then, because it is just a thin liquid. I suspect it is 30% active. I might try MEA-LS (Texapon MLS CP), S-2 (sulfosuccinate) and T-42 (TEA-LS) when I get time.
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if you’re struggling to thicken your product, and your supplier refuses to disclose the active surfactant level of your SLS/SLES, it suggests your supplier is watering one or both of them downthe easiest way to check that is by measuring the density with a hydrometerfrom experience, I’ve found that a 25-28% solution of SLES has a density of around 1.1 g/cm³ at 20°C; if it’s significantly lower than that, your materials have almost certainly been watered down -
Good comment. There is at least one factor here that I have been warned about.
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How do you go about evaporating all water to find out the percentage of active surfactant?
@Belassi I still believe your Na formula has too much SLS, and too little CAPB to be properly compared to Ammonium surfactants.
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In the test sample, adding more CAPB actually reduced viscosity, wrong side of the salt curve.
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Ammonium LES foams better than sodium LES. I’m waiting to put my hand on magnesium LES as the manufacturer says (they have made tests) it is one of the best and the best compared to ammonium and sodium.
If SLS and SLES are liquids, their concentration is most likely to be around 30%. -
@Belassi have you compared ALES to SLES head to head, everything else being the same in the formula?
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No, not yet. But SLES by itself is poor. I have directly compared SLS with ALS and ALS is far superior.
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ALS and ALES are better in foaming and cause less irritation than SLS and SLES.
The problem with the ammonium surfactants (as far as I know) is stability, they are less stable than sodium in a wider pH range. Also ALS seems to damage the stainless steel. -
Also ALS seems to damage the stainless steel.
Yes, I have noticed that. It’s quite stable as long as the pH is in range. -
Does acidic pH prevents ALES from staining stainless steel?
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No. It is not so much staining, as pitting. I find that my stainless steel must be washed immediately after preparing a batch. If the finished product is left sitting (as a film, even) in stainless, the steel gets pitted. I have been wondering about the various grades of stainless. I suspect the kitchen grade stainless is insufficient. I need to do more research on this.
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316L it’s the rule, and usually what’s allowed in food and cosmetics. The diference is 2% molybdenum, which will increase the resistance to corrosion. You probably have AISI 304, that’s almost the same without molybdenum. But of course, 20% more expensive give or take.
But even 316L will get pitted, the salts are the most harmful thing to stainless steel, that’s not actually stainless. Even a small bump will prove that, it will start corroting in no time and rust will appear.
As for the SLS/SLES, I strongly suggest you ditch that supplier. Any respected supplier will tell you what you are buying and of course will give you the COA, even if you don’t buy closed container. Beyond 28% get’s pasty, and it’s really hard to water down. The best you can do is buy at 70%, since it’s not cost/effective to cut it you are pretty much safe.
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AISI 316L is the best for sure, but it has its weak points.
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A bit off-topic, but what are good steel grades for salt-ladden formulations (not shampoos)?
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@Gunther my teacher used 220 liter plastic drums to make shampoo for years and he made it for one of the bigger companies in our country. It took about 3 hours for the water to heat up using a geyser element at the bottom
But 316 SS seems to be the way to go -
For experimental work I always use glass, but glassware above 2L is pretty expensive so I limit glassware to that size. I now use large plastic buckets for shampoo work, but there is still a problem in that mixer blades are stainless so I have to see to cleaning that before doing anything else. Not really stainless at all, is it? I’ve noticed that sulfamic acid really stains it. I think that what’s happening is that “stainless” relies on a very thin passivated coat (reaction with O2) and the surfactants destroy it. I had a spill on the lab scale last week and didn’t notice, and came back the following morning to find a patch of rust had developed. My friend Mr Brillo had to be called into service.
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I was just discussing something similar with one of the forum members in pm
316 is the only way to go, 304 is garbage (for purposes of cosmetics). you might be able to get buy with some passivation, but long term the problem is that 304 isn’t stainless under salt + heat, chemical attack conditions. 316 is basic marine grade. the problem is the vast majority of equipment is made with 304, particularly at the low end. they’re not made to handle a heated saline solution, period. I consider anyone selling cosmetics processing equipment with 304 as “planned obsolescence”, as the equipment is guaranteed to degrade with regular use under cosmetic processing conditions.
> I think that what’s happening is that “stainless” relies on a very thin passivated coat (reaction with O2) and the surfactants destroy
it’s the salt. ss depends on self-passivization. once your start eroding the surface finish, this accelerates the process and the metals in the surface inhibiting rust corrosion, cease to function. ammonia compounds are very aggressive.
citric acid will fix it if you damage the lining (regenerate the surface finish by removing what couldn’t be dissolved).
see above.
How did your teacher handle the whole “thermoplastic” portion with regard to heating? Was he using a thermoset plastic? I was considering plastic at the very beginning but I was concerned about structural integrity under heating.
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