[Bill_Toge]

try fumed silica

[Bill_Toge]

@Abdullah I found 2-5% w/w to be effective

[Bill_Toge]

@jeremien you’d struggle to find a safety assessor willing to sign it off, though

[Bill_Toge]

Abdullah said:

By methocel, do you mean Hydroxypropyl Methylcellulose or something else? 
Can you write the inci name please.

a high-viscosity grade of hydroxypropyl methylcellulose

[Bill_Toge]

in fairness, formulas with a sufficiently high titratable acidity are typically self-preserving

moving back on topic: aqueous solutions of ascorbic acid are inherently unstable if there’s any oxygen present, so the only way you might be able to get a product like this with a sensible shelf life would be if you formulated it as an aerosol

also, ascorbic acid is chemically very similar to sugar, so concentrated solutions will be sticky

[Bill_Toge]

@aliciavr6 no worries, glad to help!

[Bill_Toge]

generally speaking, refatting agents (e.g. PEG-8 olive glycerides) improve the skin-feel

using sodium cocoyl glutamate as a secondary surfactant also gives the product a pleasant after-feel

using Methocel as a thickener also boosts the foam and improves the skin-feel

[Bill_Toge]

it depends on the particle size of the solids; the coarser they are, the more likelihood they have of damaging enamel

[Bill_Toge]

the oil and water parts of your formulation fundamentally incompatible - while they are efficient surfactants, coco-glucoside and cocamidopropyl betaine are both highly soluble in water, and will destabilise any emulsion

if you want to create a foaming cream and incorporate oils into it, your best bet is to use an isethionate/fatty acid system as your primary surfactant; it has several key qualities in common with soap but it’s not actually soap

[Bill_Toge]

Stanley said:

@Bill_Toge 
Just to clarify.  The out side of the hair shaft is “coated” with the pigment.  The color would show but would it be “vibrant” or just blend in with the natural hair tone?

depends on how much dye you use; more dye results in a stronger colour

it also depends on how vibrant the dye itself is - some of them (e.g. Basic Red 51) are single compounds, so they absorb light at sharp, well-defined frequencies, while others (e.g. Basic Blue 99) are a mixture of compounds, so they absorb light over a broader range of frequencies and appear more dull

[Bill_Toge]

from my experience with mouthwashes, effective preservation can be achieved at lower levels of alcohol (10-15%) if the formula also contains cetyl pyridinium chloride or a similar cationic surfactant

[Bill_Toge]

yes, hair can take up direct dyes, and basic dyes are particularly effective - they’re cationic, so they adhere strongly to the hair fibre, which is anionic

direct dyes are best if you want sharp, bright temporary colours, but not so good for more natural, subtle or long-lasting colours, which is where oxidative dyes, i.e. the ones that need a peroxide developer, really excel

also, I doubt it’s got every single one of those dyes in it, most likely it’s just Basic Red 76 and Basic Violet 1 (and personally, I’d use Basic Red 51 instead)

[Bill_Toge]

that looks like the bushing from the end of the shaft; if it’s coming off, that means it doesn’t fit properly

if you’re getting the same problem consistently with replacement parts, that suggests the stator assembly itself has been fabricated to a poor standard

[Bill_Toge]

Graillotion said:

Bill_Toge said:

the boiling point of D5 is 210 °C, and at room temperature, its vapour pressure is about 1/5000th of atmospheric, considerably less than that of water

I am curious…. what is the number for water.  Always wanted to make that comparison in my head.

it’s about 1/30th of atmospheric pressure at room temperature

[Bill_Toge]

it might be OK

then again, it might not

[Bill_Toge]

the boiling point of D5 is 210 °C, and at room temperature, its vapour pressure is about 1/5000th of atmospheric, considerably less than that of water

its apparent volatility is due to its very low viscosity, and low chemical affinity for water and most oils

as long as you keep your batch covered while it’s cooling (which is good practise in any case) you should have little if any material loss

also, adding it under vacuum would reduce its boiling point, making any losses worse, which would make precisely zero sense

[Bill_Toge]

the problem is that azelaic acid is both highly polar, and also contains a substantial carbon chain, so it’s soluble in very few solvents; what you need is an emulsion with a highly polar oil phase, e.g. a salicylate ester

alternatively you could dissolve it in dimethyl formamide, but that’s very toxic by skin contact, so it’s not an option here

[Bill_Toge]

ISO 11930 is the most rigorous method that’s generally recognised

[Bill_Toge]

also, ethyl ascorbic acid is only stable relative to ascorbic acid: it’ll go brown in aqueous formulas, but it’ll take much longer to do so

the big advantage it has over ascorbic acid is that it’s much more soluble in non-aqueous solvents

[Bill_Toge]

+1 for a premixed blend: a bonus is that they’re cold processable

just avoid using an excessive amount of salt

[Bill_Toge]

also, the reason calcium hydroxide relaxers have to be mixed with guanidine carbonate before use is because they form guanidine hydroxide when mixed

although it’s highly effective and less caustic than mineral hydroxides, it’s also chemically unstable, so it has to be formed in situ

[Bill_Toge]

oh, I see!

in that case, it’s most likely because your menthol and Frescolat MGA are less soluble in mineral oil than they are in vegetable oils, esters or alcohol; hydrocarbons like mineral oil are generally poor solvents

[Bill_Toge]

PhilGeis said:

Right, EU’s ingredient ban comparison is a ridiculous - ingredients no one would use. 
   

true, and the legislative process is completely different - ever since the European regulations were brought in in 1976, there’s been advisory panel whose entire job is to evaluate the safety of materials in question, and submit recommended courses of action to the European Parliament (as a bonus, this also makes the process very resistant to lobbying)

and in reality, the amount of materials banned due to their advice amounts to maybe a few dozen, certainly no more than 100

across the pond, this is another job delegated to the already overstretched FDA, and for this reason the wheels turn much more slowly

[Bill_Toge]

I suspect any cooling effect Frescolat MGA has will be drowned out by the 10% of menthol you have in there

[Bill_Toge]

minimalist for sure - I take an engineer’s approach to formulation, using the necessary tools to achieve the end result and no more

this also makes it a lot easier to troubleshoot if it goes tits up