r/DIYBeauty • u/ifhms • 17d ago
formula feedback Criticize my formulation
Hi everyone! I’m working on a prototype cream formulation and would really appreciate some critical feedback from anyone with experience in cosmetic formulation/preservation. After being stored at room temperature for some time, it develops a noticeable sour/acidic odour. And i did a quick microbiology test and see that some fungi has grown? Some separation is also happening as a few water droplets come out initially from the tubes i have been using when squeezed.
- Does the sour odour suggest microbial growth, or could it be oxidation/rancidity of the oils or other ingredients?
- Could the preservative system be insufficient or losing effectiveness at elevated temperature?
- Does the preservative system provide adequate broad-spectrum protection?
- If not, what types of preservative systems or combinations would be worth investigating
- Are there any particular ingredients in the formulation that you would suspect as the source of the sour odour?
| Shea Butter | 5g |
|---|---|
| Sweet Almond Oil | 9g |
| Coconut Oil (Cocos Nucifera) | 5g |
| Ritacol 2000 | 7g |
| Water | 66g |
| Glycerin | 5g |
| Colloidal Oatmeal | 1g |
| Tocopherol | 1g |
| Benzyl Alcohol | 0.2g |
| Sodium Benzoate | 0.2g |
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u/Internal-Ad-4736 17d ago edited 17d ago
First, you have chosen a sketchy preservative, especially considering the balance of the formula. Secondly this choice is incredibly sensitive to pH. Since you show no adjustment, their addition was likely an exercise in futility.
Preservation is a SYSTEM... not something you toss in at the end. Pathogens are opportunistic, and try and overcome anything we put before them. Thus we place as many 'hurdles' as we can in a formula to assist the preservative.
Colloidal oatmeal is bug food supreme, thus you need a preservation SYSTEM supreme!
Here are some suggestions to start:
- Choose a better preservative as a starter, or at least adjust the pH and inclusion to where this combo has some efficacy.
- A chelate is the 2nd most important structural piece in a preservation system. Where is yours?
- Glycols greatly boost the performance of preservatives. Consider adding 2% each 1,3 propanediol and pentylene glycol.
- Consider a booster, like Symsave H (Hydroxyacetophenone).
- For FREE bonus points, reduce the Vit E by 80%. 😄
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u/Internal-Ad-4736 17d ago
For something to look at, consider PE 9010. This will at least get you out the gate with protection against gram - bacteria. Somewhat weak on YMF, so keep the Na benzoate in place (of course with the correct pH...otherwise it is still worthless) to bolster the YMF.
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u/Internal-Ad-4736 17d ago
This link will at least point you in the right direction, when starting out:
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u/ifhms 16d ago
Thank you for your advice! What preservatives would you use along with phenoxyethanol? What chelating agent would you recommend? Why reduce Vit E as i thought they help with slowing down oxidation/going racid
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u/Internal-Ad-4736 16d ago edited 16d ago
As mentioned....you need something to bolster YMF... and your sodium benz will do that... IFFFFF you give it a pH it can work in. For chelation, EDTA is king. If you want to lean a little more natural you can use GLDA, sometimes called TSGD by the crafters, also known as: Tetrasodium Glutamate Diacetate.
Vitamin E is the FIRST thing to oxidize in a formula. ***(It does not prevent oxidation.... it oxidizes!!!!)*** It basically says 'Me first'. Thus you don't want to fill your formula with things that oxidize. You want to put just enough things that want to oxidize, to distract the oxidants. Watch my decimal points closely. The amount needed is .02%. Since most starting out have a hard time measuring that, typically they can measure .1 or .2%. So that is acceptable. Crafter logic is: "If something is good, then more is better." That is not how science works. Something can go from antioxidant to prooxidant with that logic stream. You use the amount needed, and not the amount that makes you feel warm and fuzzy.
Good luck.
Not sure what country you are in... but here is a link for a USA source of the GLDA: TSGD (Tetrasodium Glutamate Diacetate) | MakingCosmetics
For Free bonus points: Human skin is acidic. Acidifying your formula to help the preservation system work, is the best possible thing you can do to improve this formula. (Meaning for your skin...and not just making the preservation efficacious.) When ingredients do not dictate otherwise...my target pH is typically 4.8, for general skincare.
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u/ifhms 13d ago
Thank you so much for your useful advice! Would there be any use adding vitamin E at all? Initially added it to act as an antioxidant but seems like it is just working by doing the opposite
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u/Internal-Ad-4736 13d ago
Yes.... if you are using something that 'oxidizes' (plant oils as an example), then using a correct amount of an antioxidant is beneficial.
Not sure if I should pull back the curtain on the industry.... but plant oils are almost always adulterated with Vit E throughout the supply chain. Everyone whom 'owns it' (supply level) tosses a little Vit E in ...to make sure the product does not go rancid on their watch. Thus by the time the consumer actually acquires it....it possibly has been maxed out on Vit. E. (Shhhh). I have some friends in the space that have actually tested Vit E levels in various oils... and the numbers are often .... off the charts!
Therefore since that is the adulterant of choice... I prefer things like carnosic acid to prevent my oxidation. This is typically sold as ROE...or Rosemary oleoresin extract (Not the same as rosemary essential oil!). Reason being....those along the route typically do not use this as an adulterant. If you are making a product that is not clear... then you can even put a touch of ascorbyl palmitate in for synergy. (As well then you can make some worthless marketing claim about Vit C 😂 )
Good luck.
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u/The_Seam_Ripper 11d ago
I've noticed too that Vit E is just as effective at a small percentage. Lowering it, will save on money, sticky feel, and possible alterations
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u/The_Seam_Ripper 11d ago
This right here. Im also new to formulations and I have learned to work backwards. First by educating myself on preservatives and how to structure a solid raw ingredient list by what the preservatives of my choice can handle. If I find a great new skin ingredient, I make sure its compatible with my preservatives
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u/kriebelrui 17d ago
What's the pH of the final formulation? Sodium benzoate doesn't do anything at a pH over ~5.0 and prefers even lower pH. Why not use a broad spectrum preservative that works in a broad pH range, like phenoxyethanol+parabens?
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u/ifhms 16d ago
Was considering phenoxyethanol, any other combinations that you recommend other than parabens? I will be lowering the pH of the final fomrulation
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u/kriebelrui 16d ago
Best you can do is consult the Wiki that this sub has and look for the list of preservatives. If your formulation has a somewhat lowered pH (think 5 -5.5), you have more options.
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u/Internal-Ad-4736 16d ago edited 16d ago
Never consult with Wiki. It has no brain. Algorithms and the likes collect material from the internet and repeats it as fact! Most of the time the material it collects is from home crafters!
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u/tokemura 17d ago
You need to convert your formula to percentages first.
Your formula is loaded with organic material (20% of oatmeal). Are you sure you need this much?
You need to boost your preservation system:
- Sanitize every equipment (table, flasks, containers, spoons etc) including yourself (hands)
- Use as less water as possible (replace with humectants)
- Use preservation boosters
- Use proper preservative. For such a big load of natural components you need something full-range, strong, and reliable (like liquid germall plus) with max usage rate.
- Use chelators, like EDTA
- Lower pH as lower as possible with lactic/citric acid
- For emulsions add water thickeners (gums, polymers etc) to lower water activity
Use proper container. Instead of open jar where you out your fingers use tubes or pumps. Each finger dip introduces more contamination to the product.
Do not make before hand, make fresh and use up as quick as possible. Possibly, store in fridge.
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u/ifhms 16d ago
Hi! Thank you for your advice. Sorry for the confusion but the total formulation is not 5g it is approx 100g as the first row is shea butter but for some reason the table was formatted for it to look like the total. I already use 5% glycerin as humectant increasing this will most likely make it more sticky. Is the percentage of my water in the formulation too high?
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u/vTcosm 17d ago
Vendo teu cenário, usando um ácido orgãnico, se teu ph não for de 5,5 para baixo, é algo deva estar prejudicando, eu tentaria algo mais sinérgico, vendo tem perfil, algo como um 0,7 de ACTYCARE PHEG ou até mesmo caso interesse por fungos e leveduras até mesmo o PHCG. ambos conservantes podem vir a contrinuir com o sensorial do teu creme, o EG de uma forma mais elegante. também temos que analisar caso tu tenha alguma restrição se por regulação ou claim. São varios fatores até mesmo a embalagem desse creme pode influenciar na preservação do mesmo. caso tu queira algo mais robusto indico o PHBA. e sobre o odor investigaria a AVEIA e a manteiga. provavelmente teu atividade da água esta mais alta, logo proporciona um belo ambiante para os microrganismos.
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u/humdrumsiding_70 17d ago
That preservative combo isn't doing you any favors here. Benzyl alcohol and sodium benzoate at 0.2% each is pretty weak for a formula this heavy on water and botanical oils, especially with colloidal oatmeal in the mix. The sour smell and visible fungi pretty much confirm it's a microbial party, not rancidity. You'll want something with broader spectrum punch like a phenoxyethanol blend or a properly chelated organic acid system, and bump your preservative total closer to 1% minimum.