Bill_Toge
Forum Replies Created
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this is the chemical structure of CAPB
at pH 4.5, the carboxylic acid group on the end is protonated, and no longer carries a negative charge, so the overall charge on the molecule is positivethe sudden increase in viscosity is because the positive charge on the CAPB is attracted to the negative charge on the ALS, and the two come together to form a transient insoluble “gel”, which breaks down when the CAPB is fully dispersedtry adding it at pH 7 instead of pH 4.5 and see if you get the same effect; I’ll bet you won’t -
for what it’s worth, I just found it by searching for “phthalic anhydride” on the PCPC website
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the second one is probably guaiacol, used in topical anaesthetics
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@Chemist77 in my experience, any freely water-soluble surfactant will thin a polymer gel to some extent; it’s just a question of how much
cellulosics are perfectly usable, they just don’t generate as much viscosity as they would without a surfactant present -
ionic surfactants like SLS will thin all types of polymer gel, not just carbomerssome carbomers are much more tolerant of surfactants than others; Carbopol Ultrez 20 and Ultrez 21 are much better suited to this type of product than Carbopol 940
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even with the xanthan gum, your emulsifier (glyceryl stearate - I assume this is the SE grade) doesn’t seem robust for this type of product
I suspect the decyl glucoside, i.e. a substantially water-soluble surfactant, and the lactic acid are competing with the emulsfier for the available water, and kicking it out of solutiontry adding an anionic emulsifier, e.g. Emulgade F or Crodafos CES, and see if that helps -
your raw material is clearly contaminated, or otherwise unfit for use; if you really can’t return it, you’re best off disposing of it
and although I don’t know the position the FDA or your local regulatory body takes on chlorine, it is definitely forbidden in European cosmetics, so it’s likely your treated batch is not legally marketable, and will need to be disposed of too -
@Bobzchemist, if you put “glycols” instead of “glycol” in the second name, you’ll find the sole supplier (Estron Chemical Inc.); other sources suggest the trade name of this material is Polynex, though I couldn’t find any details about it on their website
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if it’s the genuine article, DC193 shouldn’t cause a gel to go cloudy like that; hell, in the past I’ve used it at 2% and not had any issues with clarity
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for what it’s worth, I’ve always used Euxyl PE9010 from Schülke & Mayr (INCI: Phenoxyethanol / Ethylhexylglycerin) to preserve creams, and I’ve always found it remarkably efficacious and reliable
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if it separates and forms lumps when heated, that suggests it wasn’t fully hydrated in the first place; either that or it’s not HEC, since HEC is very tolerant of heat for short periods
this brochure, from one of the world’s main HEC manufacturers, contains a comprehensive guide to dispersing it and formulating with it on page 7-9: -
it sounds to me like your problem lies in uneven dispersion and incomplete hydration, so first of all, I’d suggest adding HEC to your batch before any of your surfactants, and make sure it’s fully hydrated before adding anything else (the batch will go clear when it’s hydrated)further to @CosChemFan‘s point, it does take a long time to hydrate at room temperature and neutral pH, but it will do so a lot faster under mildly alkaline conditions (pH 7-
and at higher temperatures -
many years ago, the company I work for used to sell an own-brand range of shampoos and conditioners for salons; the material lists on the production methods went onto a second page, and the INCI lists were about as long as War and Peace
they weren’t even particularly good products, they were just stuffed full of plant extracts and useless rubbish which did next to nothing
better still, no stability tests were done on them at the time, and we recently found out (nearly a decade and a half after the fact) that the pearl in the shampoos separates within two days if you store them at 30°C or higher
needless to say, we do not make this range any more! -
@xenon126 pH 4.5 is fine for a hand soap, in fact if you use salicylic acid you need a pH between 3.5 and 4.0 for it to show any antimicrobial activityanything below pH 3 is classified as a skin irritant unless you have positive proof to the contrary, so you’ll want keep your pH above 3
@MarkBroussard you’ll need to use a LOT more glycol than that (30-40% or more) for it to have any significant effect on water activity
propylene glycol does have a preservative effect at 10-15% w/w, but this is due to its properties as a 1,2-diol rather than its effect on water activity -
my prime suspect is the bentonite, as it can absorb a lot of water - how much is in the formula?
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well Merck are a major European manufacturer of pharma grade urea, and apparently they have a sales office in Mexico:
http://www.merck.com.mx/es/contact/contacto.html
and even if they can’t help you directly, they should be able to point you to a distributor
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@Belassi, can you not get it from a pharmaceutical ingredient supplier?
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agree with @MakingSkincare - passes in extreme test conditions are positive proof of stability, but failures are generally less meaningful
also agree with @Beaver about vitamin C; frankly I’d be surprised if it didn’t discolour at 50°C
the fact that your cream looks paste-like after several freeze/thaw cycles indicates the dispersed droplets are coalescing (therefore not reflecting as much light) and suggests your emulsification system is weak
personally I’d add something like Arlacel 170 (INCI: Glyceryl Stearate / PEG-100 Stearate) or Emulgade F (INCI: Cetearyl Alcohol / PEG-40 Castor Oil / Sodium Cetearyl Sulfate) as a secondary emulsifier
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yes, there is a difference
PCA stands for pyrrolidone carboxylic acid, which is not the same thing as lactic acid
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@Ruben also, in my experience cyclomethicone is a lot less volatile as part of a mixture than it is on its own
one way of gauging loss on heating would be to heat your oil phase (just your oil phase) to the temperature you intend to emulsify it at, holding it there for a while, and watching to see if any visible vapour comes offand if you weigh the container before and after heating, you can make it a quantitative test -
Bisphenol A is banned under Annex II/1176 (it’s classed as a category 2 reprotoxin), so you cannot legally use it in cosmetics:the EFSA came to their conclusion about the use of BPA in plastics because consumer exposure to it is very low - it remains within the plastic, and does not come into contact with food or drink
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even with a mousse pump, you still need some kind of surfactant to create lasting foam
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well for starters, they’re not using standard INCI or CTFA names for most of their ingredients, so it’s clear they’ve got a pretty cavalier approach to labelling regulations
also, there’s nothing declared on the label that would make it foam, which is a pretty fundamental requirement for mousse
with that in mind, I’d bet they’re using a synthetic polymer and not declaring it on the label
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as @Bobzchemist said, Evonik are a German company, and they don’t like dealing with small quantities directly; to get their products you’ll need to contact their distributor in your area
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in rinse-off products, the allergens are declared on the label if they’re present in the final product at 0.01% w/w or morein leave-on products, allergens are declared on the label if they’re present in the final product at 0.001% w/w or moreyour fragrance supplier will have a declaration stating what levels of declarable allergens are present in a given fragrance; to find out the levels in the final product, multiply the values on that declaration by the inclusion level of your fragrance