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TEA stearate manufacturing: odour/colour
Hello everyone,
I’m trying to duplicate something like:
http://www.neutrogena.com/product/facial+cleansing+bar.do
Ingredient List:Triethanolamine, TEA Stearate, Sodium Tallowate, Glycerin, Water, Sodium Cocoate, Sodium Ricinoleate, Sodium Oleate, Cocamide MEA, Sodium Stearate, BHT, Tocopheryl Acetate, Tetrasodium Etidronate, Trisodium HEDTA, Disodium Cocoamphodiacetate
As seen, there is no colour or fragrance (these are the claims I’d like to keep too). From my experiments I have determined that the colour most likely comes from heating the TEA stearate for prolonged periods of time. This causes a colour change from clear to yellow to burnt orange to brown. The Neutrogena brand is typically found in the darker yellow to bright orange from what I’ve seen.
Most are a bright orange so this is the colour I want to achieve. I have been unable to find TEA stearate in any quantity, let alone the correct corresponding colour I need, so have been making my own from stearic acid with an excess of TEA. This method has been working fine for achieving the colour. The problem is along with the colour, heating the TEA stearate develops an undesirable odour that I can best describe as burnt/soapy. I typically make the TEA stearate by heating TEA and stearic acid on a hotplate at 85C for 10-15 min. When complete I’ll keep heating until the desired colour is achieved.
My question is: can anyone think of a way to eliminate or greatly reduce this odour? It is quite noticeable and the bar should be fragrance free. What I have tried so far:
1) TEA + Stearic acid at 85C and holding at that temperature until colour is achieved; very noticeable odour.
2) TEA + Stearic acid heated at 85C until TEA stearate is formed then reducing temp to 55C until colour is achieved, no difference to odour
3) TEA + Stearic acid heated at 55C to make TEA stearate (appears to work) and held until colour is achieved, no difference to odour
4) Melting the stearic acid and adding the anti-oxidents (BHT & sodium metabisulfite) before adding TEA; no difference in odour
I have heated stearic acid on its own and tea on its own, neither will change colour on their own or develop this same odour.
Any ideas or anything I’ve missed? Any help is appreciated. Sorry if I’ve missed any info
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6 Replies
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This is really close to the edge of things I can talk about, but - look into Pears soap, and maybe there are other ingredients you can heat that will give you color without odor?
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Pears soap is subject to formulation changes and complaints from consumers but, when I worked at Unilever, Pears soap came off the production line without any brown colour. It was only on storing that the colour developed. With the later formulation the colour is produced by dyestuffs.
Regarding the Neutragena product, I think that the TEA stearate is formed in situ thus:
Stearic acid, Sodium Tallowate, Glycerin, Water, Sodium Cocoate, Sodium Ricinoleate,
Sodium Oleate, Cocamide MEA, Sodium Stearate, BHT, Tocopheryl Acetate,
Tetrasodium Etidronate, Trisodium HEDTA, Disodium Cocoamphodiacetate are mixed and heated just sufficient to melt and form a homogeneous mass, the requisite amount of TEA is then added and mixed well (crutched). I expect that during this procedure that the mass will clarify (provided no air has been incorporated during mixing).The colour will most likely develop on standing. I note that there is BHT declared - this is known to form a bright yellow colour in soaps.
BTW I’ve found an alternative LOI for the Neutragena product:
Neutrogena
Transparent Facial Bar Original Fragrance Free
Tea-Stearate, Triethanolamine, Sodium Tallowate, Glycerin, Purified
Water, Sodium Cocoate, Sodium Ricinoleate, Tea-Oleate, Cocamide Dea,
Fragrance, Tocopherol.Note:
1. described as Fragance Free but Fragrance is declared.
2. TEA and TEA Stearate are transposed.
3. Cocamide MEA in one, Cocamide DEA in the other. -
@bobzchemist I’ve looked into the original pears soap. The rosin certainly fits the bill in terms of colour, but the soap chemistry is quite different I see between the two bars. Hopefully it can be incorporated at a low level but impart high intensity colour so that it won’t affect the hardness, foaming, and overall harshness without a major base rework being necessary. I ordered a sample to try and see.
@johnb Interesting, from all the patents I’ve read it sounded like the TEA, stearic acid, BHT mixture was made first and the “water soluble” items and sodium soaps added after they were prepared. I’ll have to try adding the TEA last next. My initial thoughts were reaction time would be quite slow but the change in clarity should make the end point quite obvious.
Thanks for both your help!
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One of the reasons that Pears soap was reformulated was to remove the rosin (colophony) which is a potent allergen when oxidised. It is inadvisable to use colophony in any cosmetic products because of the propensity to oxidise.
Don’t be too influenced by descriptions of methods described in patent specifications. These often do not reflect the processes that are actually used but just a method not the method of production.
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for my two penn’orth, I might add that in Europe, soap formation with sodium and potassium salts is exempt from REACh regulations - i.e. it is not ‘officially’ classified as a chemical reaction, and manufacturers don’t have to register their product with European Chemicals Agency if they make more than one ton per year
however, this exemption does not cover TEA soaps; this is the main reason why many branders in Europe have moved away from them in recent times, and a likely reason for apparent discrepancies between European and US formulas for the same product
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If you look at other commercial transparent soap formulations, you will see several sugar-based ingredients. Sugar browns very well with heat. Maybe these other ingredients will also?
That’s the last hint I can give - this is too close to what I’m currently working on for any more.
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