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What preservative for syndet bar?
I have been a lurker on this forum and hobbyist with regards to lotion making for a few years now. I am not a chemist, but I have a solid background in the biologic sciences. I even did research for a few years in college before I realized that it was NOT for me. Anyhoo, enough of an introduction…
I am trying to make a solid syndet shampoo bar, but I have a question regarding preservatives. I’m waiting for my solid surfactants to come in the mail tomorrow, so I haven’t tried to make one yet. Different sources say different things regarding what preservative to use. The basic recipe below comes from Swift Crafty Monkey who says because there is no water, she prefers Phenohip. That doesn’t make sense because there are aqueous solutions in the formula as well (liquid surfactant, hydrolyzed proteins, etc), so it’s not really a 100% anhydrous mix like an oil based scrub. Another website (I think Making Cosmetics) said NOT to use phenohip because it’s hydrophobic and will get caught in micelles in the bar and not do any good, which (if true) makes sense. Most of the Syndet shampoo bars sold on Etsy either don’t list or don’t contain preservatives, and google has provided me with nothing concrete (I’ve been searching for a few weeks).
Basic question is, I don’t think leaving a preservative out is a good idea, but with conflicting evidence, which is better for this type of syndet shampoo bar? I have glutathione/sodium benzoate (not try broad spectrum as I understand it) and liquid germall plus at home, so would either of those work?
Basic formula for completeness (I don’t have my actual recipe in front of me, and I plan on experimenting with exact proportions, so I know this may fail miserably, but no way to know until I try)
50-65% powdered surfactant (I don’t remember exactly the proportions I’m going to try, but surfactants are SLSA and SCI)
10-26% liquid surfactant (I have decyl glucoside and coco betaine)
2-7% stearic acid
1-3% emulsifying wax (I have BTMS)
2-7% conditioning agent (Incroquat or BTMS, but I have BTMS, so it should be able to do double duty)
2-3% cocoa or shea butter
1-2% hydrolyzed protein (I have quinoa and hydrolyzed wheat)
1-4% silicone (will probably leave out b/c I don’t like silicone)
0.5-2% panthenol (I know how this forum seems to feel about “puffery” ingredients in wash-off formulations, so with some of these, I want to try to do some knock-out experiments to find out what is necessary and what is just marketing)
1-2% fragrance or EOs
0.5-1% preservative
Thanks in advance, and sorry for the long post, but I wanted to make sure you had all the info.
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13 Replies
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personally I’d go for Liquid Germall Plus, as it’s readily water-miscible and active over a broader pH range; Phenonip, and other phenoxyethanol-based preservatives, are not very soluble in water, and they are ill-suited to surfactant-based products
also, you’ll have a lot of trouble trying to combine a conditioning agent like BTMS (cationic) with your anionic powdered surfactants - I’d suggest leaving it out
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Excellent, thank you for your advice.
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BTMS is a cationic material - not an emulsifying wax and will be incompatible with the main detergents in the bar.
Silicones act as efficient defoaming agents - do you really want this?
No need to add protein or panthenol - totally pointless.
As you are not adding any extra water and the liquid detergents will be already preserved there should be no need to add further preservative. The high osmotic pressure exerted by the detergent mix will prevent the growth of almost all micro-organisms
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Interesting that you guys are saying the BTMS won’t work, but every recipe has it in there, and listed as an emulsifying wax. Just going to have to try one with and one without and see what the difference is. The only other E-wax I have is Ritamulse, and I’ve tried to use that in hair “lotions”… it was awful. Sticky, straw-like messy, awful. The BTMS provides better hair glide from what I understand.
Not doubting or questioning anyone, but I feel like the only way to learn is to try. Is there maybe a different set of detergents that would work better? Maybe that is why most people that make them complain of them being “rough” or “rustic” looking, not smooth…
For the silicones, I personally don’t like silicones in general, so I wasn’t planning on putting them in. I just put the basic recipe outline for completeness, and I’ll tweak/personalize. As for the protein/panthenol, I was going to try with/without and see, but my guess is that if I end up selling the bars, I’ll leave them in for the marketing as long as they don’t add too much to cost to put them in.
I didn’t think about the liquid detergents being preserved or the osmotic pressure. There’s another “knock-out” experiment.
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Assuming that your bar is an alternative to toilet soap as a personal cleanser, have you considered the problems there are in formulating a bar that will sit in a soap dish and not turn to mush?
The biggest selling non-soap “soap”, Dove, contains a large quantity of real soap in an effort to give “dish stability”. I doubt that your formula will do that.I worked for Unilever at the time Dove was being developed and although I was not directly involved in its development work, I was aware of the difficulties associated with the poor “dish stability” and, even now, syndet bars and “combi” bars (such as Dove) have poor integrity on storage in a soap dish.
LOI Dove:
Sodium Lauroyl Isethionate
Stearic Acid
Sodium Tallowate Or Sodium Palmitate (Soap)
Lauric Acid
Sodium Isethionate
Water
Sodium Stearate (Soap)
Cocamidopropyl Betaine
Sodium Cocoate Or Sodium Palm Kernelate (Soap)
Fragrance
Sodium Chloride
Tetrasodium Edta
Tetrasodium Etidronate
Titanium Dioxide (CI 77891).
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I was directly involved in Dove at Lever together with a myriad of syndet/soap syndet bars.The use of 80/20 Tallow/coconut soap at 10-15% will reduce slop(overnight wt loss) and also makes Dove Ploddable.Stearic aill reduce PH to 7.Adjust final moisture to about 5% and an antimicrobial PRESERVATIVE is not needed but ADD antioxidant such as BHT.Hope this helps Dr Bob
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You must be very old, DRBOB.
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Yes I have been here awhile:sounds like you also.Remember age is only a number.
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Huh. Couple of youngsters. In my day, Queen Victoria publicly declared makeup improper. “It is viewed as vulgar and acceptable only for use by actors.”
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Wow - how many ex-leverites do we have on this forum, anyway? I got my start in the industry working on bringing the Snuggle fabric softener formula to the US.
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Leverites! Sounds like a Religious cult. I heard Dr. Bob has been around so long, his first formulation was called “mud.” 50% wt.wt dirt to 50% wt./wt. water. Mix until homogenous. (Just joking by the way).
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Cute, but you neglected to add preservative
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