Mayday
Forum Replies Created
-
According to this paper, they got a solubility of 5.947 mol IPBC/kg in ethanol at 25C. Given a molar mass of 281.03 g/mol, that gives a solubility of 167.1% in ethanol.I don’t think I’m mistaken in my interpretation, because of the following passage:
[…]The solubility of
triclosan and IPBC in different alcohols is too high to be measured by
the analytical method; thus, the gravimetric method was selected
for this study.[…] -
Not formulating shampoo—I’m not aware of any specific considerations for shampoo over other water based formulations. I did find a warning about electrodes being damaged by detergents, particularly cationic ones.
I’m impressed with the Apera PH20 for the price, though I would recommend getting the combo kit if you want to calibrate frequently and take care of it properly. The plastic solution holder makes this a lot more convenient (though be careful with this lids if you buy it—the hinges are fragile…). Readings stabilize quickly enough (30s or so) and are consistent.I also have the PH60, but the PH20 combo kit is good enough unless you need the extra precision. -
One more suggestion is that you can look for patents for products containing Glycyrrhetinic Acid, and see if they describe how they formulate with it.
-
I was curious and looked into this a little but don’t have an answer. The CIR assessment may be useful to you since it has some information on usage levels and solubility of the different molecules in this family.If it’s soluble in acetic acid, perhaps you can dissolve it in that and then adjust the pH down from there.
-
On the chemistry: a lot of energy is released in that reaction, so it is not practical to reverse it. Sodium chloride is an extremely stable compound.
According to the Wikipedia page, HCl is manufactured on an industrial scale directly from hydrogen and chlorine gas. HCl is more stable than H2 or Cl2 individually, so the reaction is easy to proceed—the opposite of trying to break up NaCl.
Edit: found the process. It does come from mostly NaCl (in brine/seawater?) but is costly in terms of energy. https://en.m.wikipedia.org/wiki/Chloralkali_process
-
What about Hydroxypropyl Cyclodextrin? Would this have any effect in a stick deodorant? (Hydroxypropyl-beta-cyclodextrin is a cyclic polysaccharide that is the deodorant ingredient in Febreeze, which traps VOCs within the ring structure).
With respect to baking soda, I thought the odor neutralizing effect was actually from its alkalinity— because odors tend to be acidic—but that is also the source of irritation potential.
-
Ethanol and IPA reduce the surface tension of water, though I’m not sure the magnitude of effect if you already have surfactants. Or if it’ll inhibit soaping in an emulsion.
Anecdotally, ethanol or IPA reduces the foaming of a dilute dawn dish detergent solution. I think it boosts the cleaning potential also (seems to pick up skin oil more efficiently from my glasses) but I haven’t AB tested it properly and may be fooling myself.
-
Does anyone have bad experiences with ethylhexylglycerin and know it to be the cause? There’s another product I know about that caused dermatitis and I suspect it was that ingredient.
-
Found PEG-8 Dimethicone: https://www.makingcosmetics.com/ELL-PEG8DI-01.html
Another thread: https://chemistscorner.com/cosmeticsciencetalk/discussion/2730/replacement-for-peg-12-dimethicone
-
Not a scam on the basis of marijuana vs. hemp, at least. It must be manufactured for legality in the US.
-
I have lotioncrafter 90% lactic acid. I mixed 5% and 10% solutions by mass of lactate to water.Mixing 5% lactate to water: 2.50g lactate and 47.5g water. With a 90% lactate solution to start with, I mixed 2.778g lactate(90) and 47.222g additional distilled water. I calibrated both my pH meters and measured the distilled water measured at pH 5.5 and 5.30. After adding the 2.778g lactate(90), got pH 1.9 and pH 1.84.For 10% lactate to water: 5.306g lactate and 47.812g water. Added 3.118g lactate(90) to existing solution (not including calculations here, got messy). Got pH 1.7 and pH 1.68.I am suspicious of the 1.2 and 0.5 because I don’t think lactic acid can get that low at 5% based on my measurements. If it’s that low, I wonder if it could be adulterated with HCl or some other strong acid. How are you measuring pH?
-
Could you source goat milk fat instead of goat milk? Then it would mix easily and you’ve included the most important part.
Could you rehydrate goat milk with water and/or ethanol and then evaporate it out at low heat? Though the ethanol could curdle the milk and residual water could require preservative.
(Disclaimer: I am a novice and don’t have any practical experience in this area.)
-
That seems like a lot of sodium chloride. Solubility at 25C is only 360g to 1000g water. So 3 lb NaCl to 8.33 lb water (1 gal).
Are you trying to saturate a water solution, or are you doing something else like a suspension?
-
Mayday said:You are using two orders of magnitude more Chlorhexidine Digluconate than you should be for cosmetic purposes and one order of magnitude more than for medical antiseptic purposes.
@MurtazaHakim Rereading your ingredients list, I see I misread your concentration: you’re using 20% of a 20% solution to give 4% final. Are you formulating an antiseptic handwash?
-
Please thoroughly read the Cosmetic Ingredient Review safety assessments for the ingredients you are using. PR92.pdf from 1993 has the toxicology and animal testing data. You are using two orders of magnitude more Chlorhexidine Digluconate than you should be for cosmetic purposes and one order of magnitude more than for medical antiseptic purposes.
Also, keeping healthy skin sterile is not a good idea because you’re supposed to have some friendly microbes on your skin.
-
vitalys said:@Mayday What do you mean by saying this: “I’m working within a tight osmolarity range, and hope that using HCl will give me more room for my humectant while reducing the buffering capacity of my formulation…”Most solutions do not need to be iso-osmolar with human blood (~300 mOsm/L). Some should be, such as water-based personal lubricant. Other products could benefit from being iso-osmolar, such as a gentle face wash.My guess is that a face wash formulated to be iso-osmolar, with ingredients at concentrations known to not cause ocular irritation, the absolute minimum buffering capacity (by formulating to minimize pH adjustment), would be non-stinging to eyes even with direct application. Obviously, formulating eye drops is outside the realm of cosmetics, but there are principles that can be applied to cosmetic formulations.
-
vitalys said:@Mayday According to your conclusions regarding using HCL, you may also give it a try to HNO3 or let’s say H2SO4… Could you explain why HCL?See this comment by Perry.pH is related to the concentration of H+ (aqueous) ions in solution. They are actually H30+ ions (hydronium ions) because the hydrogen from the solute is too unstable alone. Free Cl- (aq) ions will be equivalent to the Cl- (aq) ions from NaCl dissolved in water if you have any salt in your formula. So HCl will have no “side effects” besides the extra electrolyte. The “purity” of HCl is why it is used extensively for pH adjustment in labs.I haven’t studied the chemistry of nitric or sulfuric acid. SO4 (sulfate) is apparently used as an osmotic laxative, but I imagine it would smell/taste awful and rotten. NO3 (nitrate) is a component of sodium nitrate, which is used for meat preservation. With enough dilution, neither HNO3 or H2SO4 should oxidize human tissue (chemical burn), but I think they would be unsuitable for reasons. For one, because some idiot will use recycled battery acid rather than FCC or better grade H2SO4 and give somebody lead poisoning or something.
-
@Abdullah Thanks for the link to prior discussion. Looks like buying 10% and diluting to 1% stock would be acceptable.
-
@Microformulation I really appreciate your advice, but I wish you would elaborate more on why it’s a bad idea. Let me try to make your case, because I think I understand where you’re coming from.
- HCl in a manufacturing setting would be sourcing the highest concentration practical to work with (perhaps 37%) for cost reasons. A mistake in formulation could easily create a solution that is corrosive and extremely dangerous. If you don’t have rigorous SOP and quality control, you could hurt somebody: destroying your brand and opening yourself up to litigation and/or criminal prosecution.
- Because of the severity of a negative outcome, you would invite more regulatory scrutiny.
- Consumer perception of HCl as an ingredient would invite civil litigation and poison your brand in the case of adverse reactions, even if entirely unrelated to your product. More so if your product has very few ingredients and the HCl is not buried at the end of a long list.
- For all the above reasons, contract manufacturers will not want to manufacture your product, because they would share in the liability.
None of these are technical reasons to avoid HCl, but they are practical reasons to avoid HCl.I’d appreciate it if anyone else can chime in on this topic, in case I’m missing something important. -
Microformulation said:In many, many, many years of personal care in R&D and manufacturing, I can’t recall HCl EVER being used in a Commercial setting for Personal care.The Lab Safety issues, the Hazardous Material issues and Marketing perceptions attached makes the use of HCL naive and ill informed.If I were in your position, I am sure I would feel
the same way about another person asking this question—I would have to assume
they would hurt themself or somebody else.I appreciate the warning, and I admit I am naive, but I am not wholly ignorant of those aspects. The consumer perception by itself is likely enough to make it a nonstarter. However, I am not seeing a technical reason to avoid HCl. (Some previous discussion linking to industry usage.) At the moment, I’m formulating for strictly personal use and am prepared to give HCl proper respect as a chemical, diluting as needed and double checking pH.There are plenty of substances that can cause chemical burns and respiratory problems if mishandled. I think avoiding all of them is not practical. Lactic acid 90% has to be handled carefully, and plenty of powdered ingredients are respiratory irritants. Sodium hydroxide is caustic. It is because I am concerned about safety that I am asking about 10% and 25% HCl, rather than running out and buying the strongest concentration I can find in a misguided attempt to “save money”.vitalys said:@Mayday I doubt that either citrate or lactate at the concentrations you have mentioned above can cause any sensitivity simply because they are a significant part of multiple bichemical reactions in a human body.Metabolic citrate or lactate is one thing, citrate or lactate applied to skin or mucosa is another thing. That’s a little like saying HCl must be safe because it’s in gastric acid (~0.5% HCl). I wouldn’t want that on my skin. The concentrations and context matter.
-
Microformulation said:Why not use Citric acid? More commonly used and less dangerous.Read some representative Cosmetic Formulations and you will almost never see HCl used but almost always Citric Acid.
- HCl is the most efficient acid for pH adjustment and I would like to have HCl and NaOH readily available for their own sake. I like efficiency.
- I suspect some are sensitive to citrate in the range ≥0.2% and want the option of eliminating it without substituting a more irritating molecule, like lactate.
- I’m working within a tight osmolarity range, and hope that using HCl will give me more room for my humectant while reducing the buffering capacity of my formulation.
-
@Microformulation thanks for those links!