[Bluebird]

Thanks for sharing what you know based on your professional experience.

I think I’ll go for fragrance/perfumed options and will have a fragrance-free as just one of the options then.

[Bluebird]

Thanks, well noted!

[Bluebird]

“People may say they want “fragrance free” but they still buy products that have fragrance in them.”

Mmm this holds a lot of wisdom in it and it could be a nice piece to probe the psychology and decision making process of human beings who are not always rational or consistent.

No I don’t think I’ll just target a niche market in terms of fragrances, so this is good to know.

[Bluebird]

Yeah, ramping down could be a problem, BUT it could be that the level included by the US Inolex is just too high. I wouldn’t be even thinking about ramping down to 0.4% if the Korean branch didn’t actively recommend it.

You are right that many ingredients are food for bacteria.

Sugar, for instance.

And in Spectrastat, glycerol!

[Bluebird]

Is your brilliant friend one of your alter egos?

In any case, this is a lot of gem to read.

First, I had read about hydroxamine concern, not in the CIR report (that’s good to know it’s also there), but some Australian gov report. But there, I only read “purported concern” at low and high pH, nothing concrete. So I had asked the Inolex about this and asked whether at pH 4, there is concern of hydroxamine formation and whether they had tested. The answer was that it’s stable at broad pH and for use at pH 4-8 (but they didn’t specifically said it was tested).

I wonder where your friend found the rat study-if available, I’d like to read.

The Korean Inolex distributer told me that 0.4% has been used and tested by many Korean cosmetics producers and there’s enough data to know that it works in general. No mention of any further need of preservatives such as hexandiols. Korea is strong in cosmetics, it’s a serious industry, I do think they do have some information to say that-otherwise, it will potentially get into a legal trouble. But it is a distributer, not the developer, and also you are mentioning many things that are important to consider, if true, and clearly your “friend” is very knowledgeable and has thought a lot of this, so this makes me thinking again as well.

But what safer, effective, and also importantly, consumer-friendly (meaning, even if paraben were not bad, I wouldn’t use it if my consumers don’t like it) alternatives would you have in mind as a preservative for a low pH water based system?

I tried citric acid to adjust pH (that’s to help lower skin bacterial load), used mix of (caprylyl glycol + 1,2 hexandiol) at 0.5% (this is another ready-made mix by a cosmetics company that I used; they didn’t reveal exact ratio, but says final 0.5% will work) for anti-bacterial effect, and potassium sorbate 0.15% for anti-mold/yeast effect.

I haven’t yet done the challenge test of that yet, just read the potassium sorbate concentration for leave-on products and tried that for my prototype.

The “problem” I observed: damn it, a new smell arises!

I believe citric acid reacts with potassium sorbate, leading to the formation of sorbic acid, which has a distinct smell.

I could smell it from my formulation, my family members couldn’t, so I’m not sure how “bad” or “unpleasant” or “noticeable” this smell is at this concentration, but for my nose, I do smell this acidic kind of note that, if all things equal, I prefer not to have in the product. However, it seems it’s weak enough that a little bit of perfume would solve.

I could try using lactic acid, but that would also lead to a bit of sorbic acid I imagine, plus the smell of the lactic acid itself.

I read about sodium benzoate too, but read that citric acid+benzoate+vitC can lead to the creation of benzene. As someone who sometimes tries megadosing vitC, I really don’t fancy developing a formulation w/ sodium benzoate for this reason.

So what do we have left here? 🙁

I have a pretty strong Gram-positive antibacterial already in my formulation.

And I think capryly glycol alone or w/ 1,2 hexandiol would be fine for Gram negative bacteria.

I need something against mold and yeast.

Specifically, I need something that is against mold and yeast and preferably not have strong anti-bacterial effect, if at all.

[Bluebird]

Very interesting, pretty much everything you said.

First, you’re spot on-yes the pH is to decrease the microbial load.

Never thought pH of such a fine, specific range may have such an effect.

May I ask why or where you got this idea?

So far I’ve tested pHs 4, 4.5, 5, 5.5, and 7,

and from those pH 4 was the best, followed by 4.5, which was why I picked those numbers.

But if 4.6-4.8 has better effect, well that’d be awesome, as I feel pH of 4 is a bit lower than I’d like for skin.

What is an “emulsified deo”? Is that water type w/ oil in water stuff as deo, ex, a spray type?

Sounds like lactic acid is another thing to try.

I had picked citric over lactic because the former is smell-free while I read the latter is not, so definitely good to know that LA may be better for sensitive skin.

You said you used LA to drop the deo pH to below 4-why didn’t you use 4.6-4.8? 🙂

[Bluebird]

This looks great, thank you!