[Bill_Toge]

in addition to the above, the main technical reason against using animal fats, and the reason most cosmetic chemical manufacturers use vegetable fats these days, is the uncertain and uncontrollable composition of animal fats, and consequent lack of consistent colour, appearance, odour etc. from batch to batch

[Bill_Toge]

you seem to be describing two very different things here

do you mean a product that exists as two separate liquids inside the bottle, and that you shake before use, e.g. Dentyl pH mouthwash?

or do you mean something like striped toothpaste?

[Bill_Toge]

@heraklit 1000 euro!!!!! that’s a serious ripoff - our regular assessor charges £230 per product, and if they’re assessing several very similar products, the additional charge is about £30-50 per variant

@Belassi, by ‘ethical’ I mean someone who does the job thoroughly, actually considers the effects of the product on the consumer, and the potential for it to cause any harm during reasonable use

the vast majority of safety assessors I’ve dealt with fall into this category, but there are a few cowboys out there who will sign off any old rubbish

recent example of the latter: a customer came to us wanting to produce a hair colour remover they’d had developed elsewhere

the active ingredient was a bleaching agent meant for use on for fabric and paper(!), with little to no toxicology data, which released a considerable amount of formaldehyde in situ, enough for it to smell very strongly

and yet, despite all that, an assessor in the UK had signed it off and approved it!

[Bill_Toge]

@Belassi there is no actual regulation, but most ethical safety assessors will not sign off a product (hence, deem it fit for sale) unless they have a written record of its stability

[Bill_Toge]

plus, in any case you’d only ever use denatured alcohol in a hand sanitiser - the sheer scale of legal wrangling that would result if you tried to use potable alcohol for this purpose, and justify it, would be enough to put anyone off

[Bill_Toge]

use something other than sodium silicate for your gel; it effectively acts as cement, and will leave a residue on absolutely everything it touches

just out of interest, what’s the pH of your gel?

[Bill_Toge]

@kot you’re not looking very hard then; they’re commodity chemicals, readily available from multiple suppliers

[Bill_Toge]

no, that’s complete and utter rubbish

from Article 19 of the Cosmetic Product Regulations, emphasis mine:

“[Cosmetics] shall be made available on the market only where the container and packaging (…) bear the following information in indelible, easily legible and visible lettering:

(…) (g) a list of ingredients.  (…) For the purpose of this Article, an ingredient means any substance or mixture intentionally used in the cosmetic product 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.”

there are no other exceptions, and no derogations for trade secrets - your supplier is either mistaken or lying 

link to the regulation itself; the relevant article is on page 14/15

[Bill_Toge]

salicylic acid works well, is cheap, is relatively easy to incorporate, and won’t thin your formula significantly; in fact, if you get the pH right (3.5 - 4) it actually works better than triclosan

only point to watch is that you’ll need plenty of surfactants in your formula to ensure it stays soluble, particularly at low temperatures

personally I’d avoid using bronopol, unless there were no alternative whatsoever - even as low as 0.01% it causes terrible yellowing 

[Bill_Toge]

methyl goes in the water phase, and propyl goes in the oil phase; between them, they offer protection for the whole formula

a word of warning: if you’re using ethoxylated emulsifiers (steareth-21, oleth-5 etc.) there is a real chance that one or both of your parabens will crash out of solution and crystallise

[Bill_Toge]

it depends what kind of hair dye you’re talking about

dyes generated by oxidation (permanent / demi-permanent) are large, polymeric molecules that become entangled in the fibres of the hair, and are insoluble in most solvents - very little will shift them chemically or physically, as I know only too well from getting them on my hands!

as for direct dyes (temporary / semi-permanent), this depends what kind of colorants are used; they are adsorbed onto the surface of the hair, so they’re not attached as firmly as oxidative dyes, and they’re more easily shifted

ionic dyes (acid or basic dyes, and some HC dyes) definitely won’t be shifted by mineral oil, as they’re totally insoluble in non-polar solvents

however, non-ionic (disperse dyes, and some HC dyes) may be dissolved in oil, depending on their structure - for instance, I know Disperse Violet 1 is terrible for leaching through thin plastics for exactly this reason

how significant this effect is compared to the fading caused by washing and shampooing the hair, I don’t know

[Bill_Toge]

@ssdc you can’t say that with any truth, because:

1. most of your sunscreens don’t have any functional groups that can be hydrolysed

2. the pH of your formula is nowhere near extreme enough, and the amount of free acid or base in your formula is nowhere near high enough to cause any hydrolysis (I hope!)

3. even if any hydrolysis did happen, there is no way you could tell for sure unless you used HPLC combined with several other analytical techniques, which I’m guessing you haven’t

as I said before, the problem lies with the structure of your emulsion, and the quality of the film it forms when it’s applied to a surface

the fact you’re achieving the predicted SPF when you test the oil phase on its own, but not achieving it when the oil phase is part of an emulsion, only goes to proves this point

personally, my advice would be to try using different emulsifiers and/or rheology modifiers

[Bill_Toge]

depends on what’s required from the job; if it’s very simple, low-risk work like changing a fragrance or surfactant levels, I can see how that might be automated

if the job involves more advanced tasks, e.g. matching an existing product with a spurious/incomplete INCI list, then the sheer amount of available materials, the assorted aspects of process engineering associated with them, and the occasional thinking outside the box that’s required means that a human mind would be needed to create something in a truly elegant fashion

plus, if you want new products which meet the customer’s requirements, are stable, are reasonably within budget, and can be made correctly and consistently on your plant, that’s apparently beyond the capabilities of some humans - so there’s no hope of teaching a computer to do it any time soon!

[Bill_Toge]

@ssdc if your formula were not photostable, you’d see a gradual loss of SPF over time rather than an immediate drop; this is because your batch hasn’t been exposed to a significant amount of light (unless you’re keeping your batches on a windowsill for several months after you manufacture them)

[Bill_Toge]

the SPF achieved in practise is also very dependent on the nature and rheology of your emulsion, i.e. whether or not it readily breaks down on rubbing and forms an even film

for the amount of filters you have in that formula, 7 is a very low SPF indeed; however, I’d personally describe it as “currently unfit for purpose” rather than “unstable”

[Bill_Toge]

I believe that descaler is sold in the UK under the name Cillit Bang, and it’s made by Reckitt Benckiser

if it wasn’t a genuine RB product (i.e. it was a “bootleg”) it may well have been withdrawn due to trademark infringement; there are plenty of counterfeit branded products about

since phosphoric acid doesn’t have any environmental hazards listed on the ECHA database, I doubt it was withdrawn for environmental reasons

[Bill_Toge]

for challenge testing, I’d recommend MelBec Microbiology in Lancashire - we use them regularly and they’re a good reliable test house

for safety assessments, I’d recommend EF Chemical Consulting - reliable again, they take a sensible approach, and their turnaround times are usually prompt

don’t know about stability testing though, we do that in-house

now I’ve never used NaturallyThinking, but they seem to outsource everything to third parties (they won’t let you speak to any staff other than the receptionist if you try to phone them), and the fee they charge for a safety assessment is absurdly low - they definitely seem too good to be true!

[Bill_Toge]

personally, I’d NEVER release anything to production unless it had had a full ISO 11930 challenge test carried out on it - without the results of that test, how will you know how robust it is towards microbial contamination?  

the only time I might make an exception would be if it was extremely similar to an existing product, or if the product’s inherent microbial risk was minimal (e.g. if it were anhydrous, or solvent-based)

[Bill_Toge]

the answer is in the text you’ve quoted: it forms a gel, which prevents the oil phase from moving at zero shear, hence it prevents anything from coalescing and forming crystals

they are not solubilisers, because a solution is by definition a liquid system, and this is a solid system 

[Bill_Toge]

@heraklit the HLB system only applies to non-ionic surfactants; stearates are anionic, so they don’t have HLB values at all

[Bill_Toge]

I work for a UK-based contract manufacturer which offers a full service option (i.e. we buy the materials and packaging ourselves)

do you have existing formulas for these products?

[Bill_Toge]

1. no, acid and basic dyes are just the ionic types (acid = anionic, basic = cationic) - non-ionic types include disperse dyes and some HC dyes

2. dyes sold for textiles will be same substance, but chances are there will be no guarantee whatsoever that they’re fit for human use

depending on the manufacturing process and the substances involved, dyes can contain residual impurities that are harmful to human health, and subject to legal restrictions in cosmetics - in the vast majority of dyes sold for textiles, these impurities are not monitored and their levels are not controlled 

(incidentally, most dyes now used on hair started life as textile dyes)

3. no, you need something at least partially water-soluble, as water wets the hair and provides a means to transfer the dye onto it; the vast majority of solvent dyes are not water-soluble (or their solubility in water is extremely limited), so they will not transfer

there are several other suppliers of hair dyes around - whereabouts in the world are you located?

[Bill_Toge]

xanthan gum will give you that texture; in my view the easiest solution is to use another thickener

hydroxypropyl methylcellulose works well in this type of product

[Bill_Toge]

non-standard dyes

[Bill_Toge]

Lonza do an extract in apricot oil that they claim is efficacious:

http://glenncorp.com/wp-content/uploads/2015/01/2014_10_ReGeniStemBrightening_TDS_lowres_final-2.pdf