Bill_Toge
Forum Replies Created
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in my experience, 0.1% w/w disodium EDTA does thin carbomers slightly (I’ve used it with Synthalen K, Carbopol ETD 2020, Ultrez 10, 20 and 21), but if the loss proves to be unacceptable, it can be compensated by adding slightly more carbomer
in my experience, it has never had a detrimental effect on long-term stability
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besides any obvious preservatives, water is also missing from that list, and all of the other ingredients are water-soluble; with that in mind, I’d suggest taking it with a very big pinch of salt
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https://en.wikipedia.org/wiki/Dissolution_(chemistry)#Ionic_compounds
if an ionic salt is soluble in water, and one of the ions that make up said salt contains iron, the iron is in solution once the salt has dissolved
in biological systems like brown algae (and humans, for that matter), iron is stored and transported in dedicated proteins, so the concentration of free iron is usually next to nil
even if there is any free iron, it’d be such a tiny amount, and the dilution factor in cosmetic products is so large, that the risk to the end user would be so small it may as well be non-existent
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I suspect the smallest commonly encountered one in cosmetics is sodium laurate
sodium caprate (C10), sodium caprylate (C8) and sodium hexanoate (C6) have been shown to have some surfactancy, but below C6 the carbon chain is apparently too short to form micelles
my view is that if it can form micelles, it’s a surfactant; if it can’t, it’s not
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for that to happen you’d need iron in solution; iron oxides are insoluble except in strong acids (e.g. hydrochloric, sulphuric), so the risk is likely negligible to nil
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which polymer are you using?
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that sounds to me like your Bentone 38V hasn’t been properly activated, so there’s nothing to stabilise the product’s viscosity and rheology; the product brochure from Elementis (page 9-11) describes how to disperse and activate it
alternatively, you might want to consider using a pre-dispersed form instead
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@PeiHoong what’s your method of manufacture?
it looks like a W/Si emulsion, and the stability of those is is very method-dependent
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@johnb both forms of arbutin have recently been reviewed by the SCCS, and in both cases their verdict up to a given level has been positive; with that in mind, I can’t imagine it’ll be banned any time soon
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somewhere between 0% and 100%, I should think
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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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it might be one of those factors
then again, it might be something else entirely
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it’s likely to be the xanthan gum causing that
what are the actives?
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the main factors determining PAO are how well the product keeps once the pack has been opened (e.g. does it dry out over time), and the risk of microbial contamination from normal use
for instance, if the consumer has to put their finger in the pack to dispense the product, it will have a shorter PAO than the same product in a tube, which is essentially a one-way dispenser and much harder to contaminate
there are no rigorous rules to determine it: it is essentially an educated estimate
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no, I meant lanolin wax, which is not the same thing as lanolin alcohol
lanolin wax is like lanolin but harder, with a higher melting point; lanolin alcohol is a very hard, brittle material and quite different to ordinary lanolin
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increasing the emulsifying wax wouldn’t have the same effect - the ‘wax’ part, cetearyl alcohol, is also crumbly rather than malleable
if you’re trying to avoid petrochemicals, you can get similar effect with lanolin wax (the hard fraction of lanolin), though it’d be a lot more sticky
also, are you using hydrogenated castor oil or PEG-40 hydrogenated castor oil (the two are not the same)?
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beeswax is hard, but very crumbly: if you have it included at a high level, this is most likely where your problem lies
try partially or fully replacing it with something which is similarly hard, but more malleable, like food grade microcrystalline wax
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it’s unlikely to be caused by zinc ions in solution… zinc ions are Lewis acids, even uncoated zinc oxide is insoluble in neutral water, and a significant amount of multiply-charged ions in solution will have a major impact on emulsion stability
what’s more likely is that the acid is dissolving the zinc oxide and being consumed in the process; this would also reduce its efficacy as a sunscreen
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also, how come you have to add that much lactic acid just to adjust the pH?
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if your company is the brand owner, and your company’s name and address appears on the pack, then in the eyes of the law, you do need to register your products on the CPNP
(apropos of nothing, my old line manager, from my first 1-2 years in the industry, is one of the chemists at Stephensons)
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@Perry given how much nonsense and hand-waving there is in that response, you’d think it was written by a politician!
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by “Paraben DU” I presume you mean Paratexin DU (diazolidinyl urea), which is unaffected by ethoxylated surfactants
you could use Sepigel to thicken your product, but it’d be a sticking-plaster solution: in my view, you’d be better off finding out the reason why switching emulsifiers has caused a loss of viscosity, and what steps you can take to thicken it again
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personally, the first thing I’d do would be to run the sample through a centrifuge, in order to separate the suspended solids from the rest of the product, then run the chromatographic/MS tests on the supernatant fluid
all the dyes, resins and solvents will be in the supernatant fluid, and the pigments will be the solid matter at the bottom
also, for what it’s worth, it’s not possible to identify a substance unambiguously using only MS, but I’m sure you knew that already
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at a guess, the turbidity you saw is probably due to the mineral content of the water, which would be much higher from a borehole than it would be from a reservoir
metal ions with multiple charges, particularly calcium, aluminium and iron (most commonly found in tap water), cause soaps to precipitate and form ‘soap scum’
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@cbwp as far as the law is concerned, the Responsible Person, i.e. the company whose name is on the product’s packaging, needs to register their products on the CPNP
but in practise, customers who don’t have technical staff usually subcontract this work to the manufacturer