Bill_Toge
Forum Replies Created
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@mikebavington not in Europe, the limit is 3% in rinse-off hair products and 2% in everything else
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Tween 20 is ethoxylated, so if you want to avoid PEGs you’d have to avoid that too
Ajinomoto do some mild cleansing surfactants based on amino acids and vegetable fats; they’re sold under the tradenames Amisoft and Amilite
more details here - http://www.ajichem.com/en/products/anionic-surfactants.aspx
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hell’s teeth! what do they do, fill it into solid gold tins?!
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they’ve also misspelt “benzalkonium” and left out the hyphen in “PEG-90M”
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not shampoos, but at my last workplace we routinely used a hydrophilic grade to thicken toothpastes and given them extra suspension and pseudoplasticity
because it was a very fine powder and there was 10-15% of it by weight in each batch, it was added by means of a bottom-feeding powder eductor on the plant - during addition, we kept the vessel’s side-sweep mixer running and let the friction and shear forces that resulted from the liquid’s high viscosity do the rest of the work mixing it in (if I remember rightly, it took 2-3 hours to fully mix it into a 1500kg batch)
as @Microformulation said, a high-shear mixer would be needed at lower viscosities
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@tasiaashton, cetyl alcohol will affect the flow properties more than the rub-out - it’ll make your product thicker and more rigid, but won’t have much effect on the slip
I agree with Perry; you need to include an oil that’s liquid at or near room temperature
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polypropylene or PTFE containers are good for storage, they’re very acid resistant
you could also use 304 or 316 grade stainless steel for glycolic acid, but TCA will corrode pretty much all types of metal
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at my last workplace, we made some products where the pH varied a lot from batch to batch - if a given batch was outside the pH spec, caustic soda and citric acid were respectively used to bring the pH up or down
in process, the pH of the batch started high and was brought down with citric acid, so caustic soda additions were very rarely needed
however, it was still included on the ingredients list, because it was intentionally added to the product at the design stage, even though most batches didn’t contain it in practise
I suspect it’s being used in the same way here - to raise the pH if it’s initially too low
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I’d include a section on polymers, considering how widely they’re used
also, I agree with everyone above who said colloidal chemistry
both topics are key parts of cosmetic science, but they’re only taught in the most specialised of specialist academic courses; as a result, they’re generally the least well understood
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@mikebavington the best thing about those studies, and something the SCCS picked up on in their most recent review, is that the parabens were introduced subcutaneously (i.e. they were injected underneath the skin), meaning that the subjects were exposed to parabens in a manner not at all consistent with the general public’s exposure to cosmetics
they also found that parabens ingested or absorbed through the skin via exposure to cosmetics were rendered non-oestrogenic within 15-30 minutes in adults, and were rapidly excreted with no ill-effects
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have you tried fumed silica or hydrophobically modified fumed silica (e.g. Aerosil, ex Evonik/Degussa)?
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@jakapiggy looks like they’re using glucose oxidase as a preservative… wonder what they’d say if they found out it works by releasing hydrogen peroxide!
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the difference between this and the paraben debacle is that it’s not just a product of post-normal science and media fearmongering; it’s been prompted by an actual increase in dermatitis and contact allergies
if you want the third degree, the European Scientific Comittee for Consumer Safety has reviewed the data and published an opinion last month, which is open for comments till February 17th:
http://ec.europa.eu/health/scientific_committees/consumer_safety/docs/sccs_o_145.pdf
brief summary - their conclusion that MIT was safe for use in
leave-on products was made in good faith, but it turns out it was based on faulty data; however, using an MCIT/MIT blend in rinse-off products at <= 15 ppm is still OK -
a good way to thicken it would be to increase your total emulsifier level (while keeping the relative ratio of the two the same), and/or user a mixer with higher shear
either of these would make your oil phase droplets smaller and closer together, so they form a more rigidly structured emulsion when they solidify
unless you put a hell of a lot of it in, beeswax will have a more immediate effect on the rub-out properties of your cream than it will on the viscosity
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personally I’d avoid mixing cations altogether; it alters the structure of the surfactant micelles (which are what give you your viscosity) and can cause odd/unpredictable results, especially if you’ve got a pearliser or an opacifier in the formula too
to be honest, I’d be surprised if you get any viscosity at all with magnesium chloride - if the difference between sodium and magnesium laureth sulphate is anything like the differenc between sodium and magnesium stearate, the SLES may even crash out
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what emulsifiers are you using
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try using a different red dye; I’ve found FD&C Red 4 and FD&C Red 40 are pretty robust
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if you want to create stable bubbles in a surfactant-based product, the simplest way to do it is to add a polymeric thickener that is capable of suspending particles; in my experience, Synthalen W400 (ex 3V Sigma) and Aculyn 88 (ex Dow/Rohm & Haas) are particularly good for this