chemicalmatt
Forum Replies Created
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Affirmative, if your formulation is an invert system such as w/o or w/Si then you’ll see that separation. All of these invert emulsions are intrinsically unstable at elevated or reduced temperature conditions. I’ve had many that were stable for many years at RT though.
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As said by @ketchito You will find that acrylic disruption especially with divalent salts such as Mg, Ca as found in “l’eau marin”. Also, the acrylic opacifiers have ranges of pH compatibility and you must always add into water first before anything else, never last.
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@Greglar the formulation you refer to may actually be a cross-polymer of cyanoacrylate/acrylic acid and that “soy” material could refer obliquely to the x-linker used. Essentially it is Super-Glue. This likely involves peroxide radical-initiated polymer synthesis, not simple mixing. Be advised of this if results from mixing are not favorable.
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Sounds like an oil or similar lipid might have been added without pre-solubilizing in a surfactant cocktail. You used some good ones there attempting to mitigate but in my experience once that oil is dispersed into the carbomer gel it will not solubilize afterward. The other possibility is somebody added a cationic-charged material before the carbomer was neutralized. BTW, those cross-links are strong, it takes many months or years before they break down depending on how much UV exposure your gel gets. This is why we’ve always added benzephoenone-4 into clear carbomer gels for retail presence; 0.05% is plenty also.
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Menthol will dissolve directly into mineral oil or any other paraffinic. Plan your order of addition accordingly.
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@Fekher first thing is CONGRATULATIONS! You discovered something unique and thanks for sharing. Now, get to that patent attorney office pronto my friend! OK, there is some “prior art” involved here. The fatty acid 12-hydroxystearic acid derives directly from castor oil hydrolysis. This is a known gellant for apolar oils such as mineral oil. It works on medium polarity oils too but not as well. What is surprising is how that castor oil underwent hydrolysis - alkali are used for this industrially - yielding all that 12-hydroxystearin. Even so, you got a pretty thick substance with only 1.0% castor oil too. Pretty cool, dude!
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@LabGuy It must be restated here that virtually ALL invert emulsions are entropically unstable. You will generally find thermodynamic instability at 45C sooner or later with these creations, so don’t feel bad when it happens. Having said that, you were wise to include that BENTONE Gel to stabilize the continuous phase. The issue appears mainly in your water phase. Add much more NaCl, 3.0% will do, and reduce that Tween 80 in half. This may help but your chief problem here is the low level of water in there! Doing the math here and excluding the metal insolubles there is ~16% water and ~60% oils. Not good. You will need much more to keep this viable so some of that oil phase has to go. You may try increasing the Abil EM90, as higher the ratio of oil: water inside, the greater level of w/o emulsifier required. Honestly at this rate I would just forego a water phase entirely and go to an anhydrous system serum. Q.s. with esters and get on with your day.
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@AMS It is not clear what is described by “PPG” or even “PEG-40” and those polyols (we know what those acronyms mean) are your key thickening ingredients. E.g. PPG-15 Stearyl Ether + PEG-40 Stearate: now we have something to go on. That combo would produce a nice emulsion, BTW, one that is oxidatively stable as well. You might also use a Poloxamer PPG/PEG block copolymer to achieve 1000 cps sustainably. But alas…
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I cannot recommend this program enough. It is the longest-lived MS Cosmetic Science program (USA) in existence for a reason.
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@Aanchal If we assume CATC is cetyltrimethylammonium chloride (CETAC as we know it) the means of thickening that low solids formulation is NaCl, just plain sodium chloride salt. Add into the batch as a 20% solution at 40C and you will be surprised how much viscosity you will gain. This is the reason all those inexpensive hair conditioners on the market appear to be much richer than they are.
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@Hairlover I can only surmise the effect you observed with urea is one where the urea lifts the cuticles - literally swells the hair shaft - allowing more of the conditioning agent to incur. That would lead to a softer sensorial. Kudos to you for the discovery, my friend! A historical aside: back in the thioglycolate permanent wave era urea was used for this same purpose: lift the cuticle layer to allow faster penetration of thio into the hair cortex where it worked its cysteine cleavage chemical magic. If not for that Jennifer Aniston and her straight hair revolution we would all still be making money on perm kits.
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C12-15 alkyl benzoate is a fragrance fixative that is miscible with all those silanes, also with those esters. Triethyl citrate is also a fine fixative, but I am not so sure it will be miscible with silanes. It will be miscible with the esters though.
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@Xenk more information would be needed to give you an intelligent answer here, i.e. exactly what is SLSA (acronym violation: arrrgghhh!); how much SLSA is involved here solid state, likewise the CAPB; which “exfoliant” is used and how much; does “xantum” = xanthan and which grade/how much was used - a critical element. I could go on….
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Any material that has a significant polar charge may be considered an electrolyte. Those having ionic bonds (salts) are the most highly charged given their high polarity in relation to their mass. Those with higher molecular mass (organic materials), or covalently shared ionic functional groups have lower charge-mass ratios and are therefore less electrolytic. Amino acids and proteins are mildly charged whereas quaternary ammonium compounds are more strongly charged with ionic strength inversely proportional to their mass: i.e. cetrimonium chloride is more electrolytic than behentrimonium chloride. The ionic nature (mono-, di-, tri-valent), structure and molar mass of the anion and cation also factor into this. This is the short answer, there is much more. There will not be a test however.
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@Abdullah It’s been a while since I worked with it but isn’t STPP more soluble in cold water than in hot?
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@cocoblue the correct logical order is stability > PET USP51 > HRIPT. If the formula is not thermodynamically stable then sterility testing and safety testing is no longer important. When you have (favorable) results documented for all three then you are free to choose any CDMO you want to; no need to run these again. After >35 years in that sector I can tell you the client who comes into play with formula ownership and integrity fully vetted like this gets instant “street cred” and the deference that goes with that. You will have a distinct advantage in the price quote too, the CDMO knowing you can move elsewhere at any time.
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Yup, I’ll be working at our booth #803. Stop by and say hello or just to talk about your work, beauty industry goings-on and formula chemistry. The educational agenda there is packed with content and @Perry44 will be all over that.
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Propylene glycol is not the “wet” problem, decyl glucoside is. DEL that surfactant (why add it in first place?) and fix the PG: water ratio at 2.0 to 2.5: 1, it will work fine. You don’t say which grade sodium stearate is used, but 8.0% seems high to me. Most of these start at 6.0% with little increase from there.
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@EricT Those potassium soaps start losing their solubility the lower the pH difference. That is your haze factor. I’ll also mention piroctone doesn’t care for lower pH either, even as it is mainly insoluble to begin with. Switch those out with a standard anionic such as SLES or SLS (I know: sulfates - EEEK!) and you will feel better. Better yet use ALS and drop pH < 7.5. ALS is a better hydrotrope for piroctone olamine.
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So simple: get a sample of nearly any silicone crosspolymer gum blend from Dowsil, Momentive, Wacker, BRB, ShinEtsu. Add a small amount of phenyltrimethicone or C12-15 alkyl benzoate, then get busy shinin’ then tyres. Another approach: start out with Versagel (Calumet) then add those shiny components.
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@Camel The level 0.50% menthol will sting my eyes in a hot shower, so keep that in mind. Most of the scalp-cooling shampoos use 1.0%, so you can increase to that and find success. I could not handle it but most folks can. And, yes, you are correct to dissolve into the surfactant blend. Menthol is more oil soluble than water soluble.
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That low level of urea will not change pH significantly over time, even as it decomposes into biuret, ammonia and nitrates. The lactate buffer does work best however, so you are on right track. (Rice starch is the other.) A more cogent question is why have it in a shampoo in the first place? As a keratolytic it is not applied to hair long enough or in high enough concentration to perform any valuable function in a cleansing product. Applied as a leave-on product it will swell the cuticle allowing conditioner elements to absorb faster/deeper, but in rinse-offs?
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@Onur the SPF 50 is chiefly - but not entirely - built by nano zinc oxide, and as you surmised: likely uncoated. The other elements in an anhydrous formula such as this one also boost SPF as these are occlusives, though not UV absorbers. They function in synergy with ZnO, which deflects sunrays while the lipids block them.
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PEG-12 Dimethicone comes to mind as does butylene glycol. Both are superior plasticizers to glycerin.
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@Abdullah I recommend substituting 0.8:1 if that lauramidopropyl hydroxysultaine is the standard 50% solution and they are comping it to the standard 30% CAPB solution. A little extra sultaine helps.