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Urea in shampoo
Hi,
I have asked this question in an old thread/topic, but had been advised to open new topic. So here is my question
Stability of shampoo using Urea.I’m formulating shampoo for my client. We have Coco glucoside, sodium cocoyl glutamate and CAPB as surfactants, then we have a few moisturizers (B5, propylene glycol). And an additional of 1% urea.
I have lowered the pH to 5.5 with citric acid (use around 0,8%). After a few months (3 months +) pH is still the same.
My question: Is it necessary to stabilize the urea with a buffer solution regarding the use of a really low dosage of urea (1%). Should I expect to have problems regarding urea decay later (let’s say after 1 year or more- planning shelf life will be 2 years).
Any suggestion /experience in this field is welcome, thank you in advance for your help.
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5 Replies
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All I remember about Urea is that a sodium lactate/lactic acid buffer would help it remain stable and that sodium benzoate & potassium sorbate duo as the preservative system would be the best. These preservatives are most effective between pH 4 and 5.
I wouldn’t use Urea in a cleansing system, though. It’s very hard to work with. And there are more stable keratolytic agents like Allantoin, Salicylic acid and even Lactic acid itself is keratolytic. They all soothe/moisturize the scalp.
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Think you could do better than (just) organic acids - esp adding isothiazolinone esp. or even phenoxy
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That low level of urea will not change pH significantly over time, even as it decomposes into biuret, ammonia and nitrates. The lactate buffer does work best however, so you are on right track. (Rice starch is the other.) A more cogent question is why have it in a shampoo in the first place? As a keratolytic it is not applied to hair long enough or in high enough concentration to perform any valuable function in a cleansing product. Applied as a leave-on product it will swell the cuticle allowing conditioner elements to absorb faster/deeper, but in rinse-offs?
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Hi, Thank you for your answer.
The test that I did- shampoo with urea and shampoo without urea, there are big difference in hair softness and overall feeling of the hair. This is the only practical reason, that I included it into shampoo.
Does anyone else notice the softness hair (like silk) after using the urea in shampoo or other haircare products?
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@Hairlover I can only surmise the effect you observed with urea is one where the urea lifts the cuticles - literally swells the hair shaft - allowing more of the conditioning agent to incur. That would lead to a softer sensorial. Kudos to you for the discovery, my friend! A historical aside: back in the thioglycolate permanent wave era urea was used for this same purpose: lift the cuticle layer to allow faster penetration of thio into the hair cortex where it worked its cysteine cleavage chemical magic. If not for that Jennifer Aniston and her straight hair revolution we would all still be making money on perm kits.
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