[Bill_Toge]

cetearyl alcohol is not an emulsifier, although it is surface-active

Polawax / emulsifying wax does work, but you have to use a lot of it to get a  reasonably stable product - personally I prefer to use a combination of emulsifiers instead of relying on one material

[Bill_Toge]

what grade of coconut oil are you using - is it whole or refined?

(also, petroleum jelly is called “petrolatum”)

[Bill_Toge]

acid dyes are anionic, and your formula contains a cationic, so they’re not mutually compatible

[Bill_Toge]

you don’t need a preservative: unless I’m reading it wrong, your product has no water in it, and it won’t sustain microbial growth (also, potassium sorbate won’t dissolve in oils and waxes)

PEG-40 HCO makes the product miscible with water, but doesn’t solubilise it very well - glyceryl stearate is more hydrophobic, and mixes with both PEG-40 HCO and the rest of the materials, so it helps the product wash out

also, your product has no water, and is not an emulsion, so HLB is irrelevant

[Bill_Toge]

iin my experience, a mixture of PEG-40 hydrogenated castor oil and glyceryl monostearate (the non-self-emulsifying grade) helps anhydrous products wash out with relative ease

[Bill_Toge]

there is no simple answer to this question: the SPF you’ll achieve in practise will depend not just on the level of zinc oxide in the product, but also on the product’s rheology and its ability to form an even, uniform film

[Bill_Toge]

benzophenone-4 is very simple to use: it’ll dissolve easily, you only need 0.1% w/w of it (or less, depending on the dye) and it doesn’t need to be neutralised

in fact, it’s best keep to the pH below 7 or else it’ll turn bright yellow

[Bill_Toge]

also, a very important skill is the ability to design formulas which can be manufactured easily and consistently, and in the case of hot fills, stay reasonably stable at the filling temperature

we used to subcontract for a certain well-known multi-national brander, and they had two hot-fill products which were notorious for separating or going grainy at the temperature they were filled at: because we could make smaller batches and filled directly out of the vessel, we could do a complete filling run before they started to fail

had the formulator(s) in question taken a little more care at the design stage,  there would have been no need to subcontract it, and the brander could have saved an awful lot of money

[Bill_Toge]

* good practical skills - if you want to formulate good products, you have to have plenty of experience at the bench, and learn from your experience

* strong problem-solving, deductive reasoning and attention to detail

* the ability to define a problem or a task simply and logically, start from the beginning, and work your way through to the end (I’ve witnessed far too many colleagues and third parties needlessly overcomplicating a problem and tying themselves in knots)

* a healthy dose of cynicism - believe what you see, not what you’re told

I’ve always said this job is about an equal mixture of science and engineering, with a dash of creativity thrown in

[Bill_Toge]

on a similar subject, I found the Methocel and Ethocel technical handbooks from Dow quite fascinating, simply because they list a huge variety of applications for those products, of which cosmetics and pharmaceuticals comprise but a small part

[Bill_Toge]

@Doreen81 the colour and odour will vary depending on how pure it is, and how much it’s oxidised over time

[Bill_Toge]

what’s the pH? if it’s over 6, potassium sorbate is completely ineffective; if it’s over 5, sodium benzoate is completely ineffective

personally I wouldn’t put phenoxyethanol in a shampoo, because there are plenty of preservatives that are more miscible and less likely to interfere with the foam

[Bill_Toge]

@johnb the physical cooling effect of sugar alcohols is short, but they definitely give a cool sensation in solution too 

while I was working on an own-brand knock off of Listerine mouthwash a few years back, I found sorbitol (added as a 70% solution) greatly enhanced the product’s flavour and the cooling sensation, and was part of the reason the product had such a ‘powerful’ taste

[Bill_Toge]

it never fails to amaze me how uptight and superstitious people can get about completely innocuous things like parabens, and yet they’re perfectly happy to put a highly caustic and alkaline product under their eyes: a product which is basically cement minus the sand

[Bill_Toge]

@tai961 these companies seem to have confused drinking collagen with injecting it

one can only hope that for their own sake, they don’t inject fruit juice instead of drinking it

[Bill_Toge]

@Perry for what it’s worth, regarding 1,4-dioxane, Article 19 of the European cosmetics regs is also very clear on the matter:

“For the purpose of this Article, an ingredient means any substance or mixture intentionally used (…) during the process of manufacturing.  The following shall not, however, be regarded as ingredients:

(i) impurities in the raw materials used;

(ii) subsidiary technical materials used in the mixture but not present in the final product.”

therefore, 1,4-dioxane is not listed because it’s an impurity 

[Bill_Toge]

I’ve added a few more (mainly related to European standards and regulations) plus a few alternative definitions for existing ones, and corrected the spelling on a few others

[Bill_Toge]

any active ingredient in a hand sanitiser will be toxic to microbes, simply because the entire purpose of a hand sanitiser is to kill microbes

if it doesn’t kill microbes, it’s not a hand sanitiser

[Bill_Toge]

also, I’d question whether that castor oil actually is organic, and if so, whether it’s legal for it to be sold for topical or food use

none of our suppliers carry organic castor oil as a stock item; I believe the reason is because if they did, they wouldn’t be able to guarantee that it’s free of ricin

[Bill_Toge]

agree with @johnb - I’d stick to the original regime, you can never be too careful when it comes to micro testing

[Bill_Toge]

behentrimonium methosulphate is the key part: it’s a surface-active molecule with a charged head and a hydrophobic tail long enough to act as an effective emulsifier

because it’s cationic, it doesn’t actually have a HLB value - the HLB system is only relevant to non-ionic surfactants

the other two components are not emulsifiers at all

[Bill_Toge]

if you want to protect the carbomer from UV light you’re better off using benzophenone-4; you only need about 0.1%, and it’s more soluble

[Bill_Toge]

I suspect the amine oxide may be a causative factor too, as they’re not gentle surfactants; in the UK at least, their usage is generally limited to household products

[Bill_Toge]

cationic guar should be fine; don’t know if it’d have any effect on rheology or product stability though (I doubt it personally)

[Bill_Toge]

xanthan gum is anionic, so it won’t be compatible with the cationics - HEC would be a better choice

personally I’d use less silicone, round about 1-2%

also you’re better off using a salt of quinine (e.g. the sulphate) rather than the free base, as it’s more soluble and less likely to crystallise