[Bill_Toge]

this is written by someone who has no experience in the industry whatsoever,  whose deductive reasoning skills are very poor, and despite having a master’s degree in a hard science, is apparently unaware that natural hormonal changes can cause changes in skin temperament over time

what a load of cobblers

[Bill_Toge]

on the other hand, Seppic have a range of vegetable derived alkanes which are exceptionally pure, and physically similar to volatile silicones (non-polar) - in my experience they can be used as a like-for-like substitute

they’re the EmoGreen and EmoSmart range

[Bill_Toge]

“let P304 be the vapour pressure [of cyclopentasiloxane] at 304 K”

I’d normally put 304 in a subscript, but the ‘sub’ tag doesn’t seem to work on this board

[Bill_Toge]

ln(33.2 ÷ 101325) = ΔHvap/R × (1/483 - 1/298)

hence, ΔHvap/R = ln(33.2 ÷ 101325) ÷ (1/483 - 1/298) = 6242.486494…

let P304 be the vapour pressure at 304 K, then:

ln(33.2 ÷ P304) = ΔHvap/R × (1/304 - 1/298) = -0.413446…

hence, (33.2 ÷ P304) = exp(-0.413446…) = 0.661367…

hence, (P304 ÷ 33.2) = 1 / 0.661367… = 1.512020…

hence, P304 = 33.2 × 1.512020… = 50.2 Pa

(as an aside, I really wish there were a proper way to format equations in HTML)

[Bill_Toge]

@Milagros deberá hidrolizar el aceite de oliva, y separar los ácidos grasos de la glicerina

también necesitarás usar un ácido más fuerte, por ej. sulfúrico

para más detalles, busque “esterificación de Fischer-Speier”

[Bill_Toge]

there is a way to calculate how the vapour pressure of a given substance varies with temperature, namely the Clausius-Clapeyron equation - it’s equation (2) on this page

if you substitute P1 = 33.2 Pa at T1 = 298 K (25 °C) and P2 = 101,325 Pa at T2 = 483 K (210 °C), you can work out ΔHvap/R and thereby calculate the pressure when T = 304 K (31 °C)

[Bill_Toge]

@Will those two resins are very much the exception rather than the rule; also, Amphomer has been on the market a very long time, and was originally designed as a synthetic substitute for shellac in aerosol hairsprays

the choice of resin depends on the form of the final product, the texture you want and what’s available to you - the sheer variety of resins on the market is frankly staggering

[Bill_Toge]

speaking as a chemist with 10 years’ experience at the bench, I will say that industrial labs are nothing like academic labs, or labs on TV: if they are to serve a useful purpose they should be kept simple, have the equipment required to fulfil their function with maximum efficiency, and ideally a little bit of room for expansions and upgrades

needless to say, you do not need $40,000 worth of equipment to get good results - they ultimately come from staff training, on-the-job education and personal development

who are these people doing the pushing? do they have any relevant technical background, or any practical experience whatsoever?

[Bill_Toge]

if you try to access it in the UK (and probably in Éire too), Sephora redirects you to their French site, which appears to have no English-language text on it, and neither do the other European sites

the Far Eastern, Australian and New Zealand sites are in English though

[Bill_Toge]

two words: bug food

there are other, much lower-risk ingredients available

[Bill_Toge]

further to @Doreen‘s posts, atmospheric pressure is around 100,000 Pa at sea level, so anything with a vapour pressure of 33 Pa is non-volatile

for comparison, water has a vapour pressure of around 4,000 Pa at 30 °C, around 20,000 Pa at 60 °C, around 47,000 Pa at 80 °C, around 70,000 Pa at 90 °C, and 101,300 Pa at 100 °C, where its vapour pressure equals the atmospheric pressure and it boils

[Bill_Toge]

VP/VA copolymers work over a wide pH range, only old-fashioned resins like Amphomer need to be neutralised with a base

[Bill_Toge]

if by sunscreen actives you mean additional UV filters, then the answer is no

[Bill_Toge]

depends what you mean by ‘recent’

in the last few years, HC Blue No. 15 and Basic Blue 124 are vibrant blue temporary shades that have been introduced onto the market to replace the now-banned Basic Blue 9

[Bill_Toge]

acid dyes generally have very poor washfastness on hair, due to the fact hair carries a negative charge, as does the acid dye, leading to electrostatic repulsion; this is why the vast majority of temporary hairs dyes are basic (i.e. cationic) or neutral

[Bill_Toge]

for what it’s worth, sorbitan olivate is created by dehydrating sorbitol and then reacting it with olive oil fatty acids in some kind of esterification reaction (e.g. Fischer-Speier); likewise, cetearyl alcohol is reacted in the same way to form cetearyl olivate

[Bill_Toge]

the wax is there to alter the texture of the hair, and act as a secondary fixative - lanolin wax is particularly sticky, and can be hardened when combined with microcrystalline wax

[Bill_Toge]

my former boss was one of the original chemists who worked on that Fudge product many years ago, and still had the original formula: try reducing the beeswax, and adding VP/VA copolymer and PVP K-90, and see how you go

[Bill_Toge]

@Doreen you’d struggle to get a pH above 9 with TEA or AMP, they’re just not that strong as bases

[Bill_Toge]

we always used to buy them from a wig manufacturer

[Bill_Toge]

@Will ceteareth-(n) would make it more like a conventional cream, oleth-(n) would make it more fluid, unless used at high levels (10% w/w or more in total), then the product would start to resemble the oil phase itself

it’s difficult to explain without a physical example to hand

[Bill_Toge]

the most likely culprit is the potassium glycyrrhizate/salicylic acid combination: I should think any form of acid would turn it into a gel, not just an inorganic one (the laws of thermodynamics are not picky)

[Bill_Toge]

aloe vera is terrible for going brown, especially at high temperatures

[Bill_Toge]

they could try permitting bisoctrizole and bemotrizinol (20 years after the rest of the world has), they’ve got tons of safety data behind them!

Gunther said:

Insufficient data is no reason for banning ingredients.

on the other hand, many hair dyestuffs on Annex II of the cosmetics regs have insufficient safety data, and the volumes were so low their producers had no commercial incentive to generate it, so they were delisted for that reason

granted, given that hair dyestuffs potentially pose a much higher hazard than most cosmetic materials (and by that point, several dyestuffs previously thought to be benign had been found to be human carcinogens), this is hardly a typical situation, but still

[Bill_Toge]

oleth-(n) and ceteareth-(n) give emulsions with very different properties, due to the difference in volume

ceteareth-(n) is linear, while oleth-(n) is wedge-shaped and takes up more space at the water/oil interface, meaning it results in fewer molecules per micelle and therefore a larger number of micelles; the difference is particularly noticeable at high levels of emulsifier