Bfd
Forum Replies Created
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No no, I don’t. Haha customer is king, even if misguided. The decision to use parabens or not use parabens doesnt say much about my style. I also wouldnt say I am putting out or am comfortable putting out rotten formulas. Even with the strictest standards, there are great solutions available. Yes, I mourn the unnecessary loss of silicones but have you tried esters? If I don’t know a solution yet, I make sure they understand the difficulty of the ask up-front. To me, our job is all about finding answers to these seemingly impossibly demands. Therein lies the fun. I’m not trying to sell the same lotion, cream, serum, gel, conditioner, etc. over and over again. Sounds boring.
-bfd
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Can you share a sample formula that’s giving you the powdery feel? Maybe I can ID the culprit better looking at the whole picture.
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A neutralized carbomer unit has negatively charged carboxylate groups on a carbon backbone. In an aqueous gel, the carboxylate groups repel one another (electrostatic repulsion), giving rigidity to the structure. They all want their own space, no overlapping.
The problem with adding electrolytes is that they screen the negative charge on the carbomer units. The distance of repulsion between units is diminished the higher the ionic strength of the system becomes. With positively charged ions sandwiched between the negative carboxylate groups, carbomers get cozy together and viscosity plumets.
At some point with addition of acids, the pH drops low enough (<5) that you’re protonating the carboxylate groups back to carboxylic acid. You might think this means you’ve reset to your starting point, but the persistent high ionic strength of the solution will prevent the carbomers from ever contributing meaningfully to viscosity again.
At pH 6.5, used at the same concentration, citric acid will contribute 3x more protons than lactic. Three protons are significantly worse than one, but one will still cause some electrostatic screening.
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I agree. Tell us more about the colorant. Is it red?
