What preservative to use for my formula ? - Cosmetic Science Talk

What preservative to use for my formula ?

Hello Chemist experts!

I am new to the forum as well as making my new formulas. Please excuse any amateur mistakes and in my approach to this question.

Through educating myself online with basic chemistry literature I have attempted to create my own waterbased pomade. Today I have a successful formula with the texture, scent and effect that I wish for however the product goes rancid after a couple of days due to lack of a preservative.

Formula:

Based on a 100 Gram batch:

Water 52 G 

Beeswax 20 G - 52.6 % of oil base - 6.31 hlb value
Jojoba oil 7 G - 18.4 % of oil base - 1.11 hlb value
Candellila wax 5 G - 13.2 % of oil base - 1.91 hlb value
Shea butter 4 G - 10.5 % of oil base - 0.84 hlb value
Coconut oil 1 G - 2.63 % of oil base - 0.21 hlb value
Vitamin E 1 G - 2.63 % of oil base - 0.16 hlb value

Total oil base HLB value: 10.54

Emulsifiers:

10% of total formula

Peg- 40 Hydrogenated Castor Oil 6.5 G - 6.5 % of Total
Soy Lecithin 3.5 G - 3.5% of total

Emulsifier mix HLB value 10.6

Essential Oils 10-15 drops 

Question:

How can I add a good preservative to my formulation to keep it free from fungus, mold and microbes to increase shelf life (hopefully a couple of months) ? How can I calculate the ratio ? I have been looking into potassium sorbate do you think this would be a suitable preservative ? Please keep in mind that I am trying to make a "natural" as possible product.

P.S this is only for my personal use.

Thank you for your help.

Comments

  • From your ingredients I'm not sure if this is a water based pomade. Yes it contains water but the waxes are too high for it to be considered water based. For the preservative, I swear by Dermosoft OMP for preservative-free claims. 
  • @Kara90 phenoxyethanol-based preservatives like Euxyl PE9010 and Liquapar MEP work well in this type of product; 1% w/w is a good starting level

    I'd avoid potassium sorbate, not least because there's a very high chance it'll destabilise the emulsion and cause the product to separate (salts and emulsions don't mix)

    @crisbaysauli it's an O/W emulsion, how can it not be water-based??
    UK based formulation chemist. Strongest subjects: hair styling, hair bleaches, hair dyes (oxidative and non-oxidative) I know some stuff about: EU regulations, emulsions (O/W and W/O), toothpaste, mouthwash, shampoos, other toiletries
  • @Bill_Toge - Thank you for the tip. Would you by any chance know a good supplier for locations in Europe where I can get these preservatives. Are they  broad spectrum or would I have to mix ?

    Another very basic question, 1% w/w does that mean 1% of the Water in my case 0.52 Grams?

    Overall what do you think of my formulation ?

    @crisbaysauli - The majority ingredient is water which is why I called this water based however I don't know if that is technically the correct thing to do in the world of cosmetics chemistry.

    Thank you for your answer, hope to get some more insight by you all!
  • most of these should work well:

    http://www.gracefruit.com/additives/actives/preservatives/

    1% w/w = 1% of the whole formula, weight per weight (i.e. 1 g per 100 g)

    can't really comment on the formula itself without seeing it in the flesh; on paper though, many aspects of it are typical of water-based styling pastes (similar wax/emulsifier levels, similar types of waxes used, etc.) and there's nothing obviously wrong with it
    UK based formulation chemist. Strongest subjects: hair styling, hair bleaches, hair dyes (oxidative and non-oxidative) I know some stuff about: EU regulations, emulsions (O/W and W/O), toothpaste, mouthwash, shampoos, other toiletries
  • @Bill_Toge ;

    Thank you for the great advice. I have looked in to the preservatives from the link that you provided and I think it falls on :
    • GRACEFRUIT® PRESERVATIVE POG
    Do you think this is suitable for my formula ?

    Thank you once again for the value provided.
  • Sorry for double posting. I wonder if a blend of pure 90% Phenoxyethanol and 10% Ethylhexylglycerin would have the same broad spectrum effect as the grapefruit products ? The main reason is that the shipping of grapefruit product would be 18 € while I found that blend mentioned above locally which would be cheaper?
  • That depends on what chemicals are in the grapefruit product.
  • Be careful not to confuse grapefruit and Gracefruit!
  • @perry @johnb @bill_Toge

    What do you think of the blend mentioned above for my formula ? 90% Phenoxyethanol and 10% Ethylhexylglycerin


    I have ordered it and I will try it I'm just wondering what your predictions are. Am I on the right track ?

    Thank you

  • I have used a similar mixture and found it successful.

    However, my formulations were completely different to the one you are considering.
  • @Kara90 - It can work or it can not work. It really depends on a number of factors such as your manufacturing conditions, the raw materials you're using, the microbes the batch is exposed to, and more.

    The only way to know if something works is to try it. 

    In truth, you'd be better off using parabens since Phenoxyethanol can cause irritation for some consumers. 

  • If you're really seeing rancidity, which comes from the oxidation of oils and fats, and not just bacterial contamination, you are going to need to add a strong anti-oxidant, like BHT, to your formula, on top of a preservative system.

    You'll be able to tell if you need this after you add your preservative system and put your product on stability for a bit.

    Also, I've always found it very helpful to distinguish between "actual" HLB values and "required" HLB values when planning a formula - otherwise, it can rapidly get confusing. Only surfactants have HLB values. Everything else has a required HLB value - which is what HLB a surfactant must have in order to emulsify that ingredient.

    I really wish more websites would make this distinction - fats, oils, waxes, etc. should have rHLB numbers, not HLB numbers. 
    Robert Zonis, Sr. Formulation Chemist, Beaumont Products "All opinions and comments expressed are my own, have no relation to Beaumont Products, are fully copyrighted, and may not be used without written permission."
  • @Kara90 from personal experience, I've found a 90% phenoxyethanol / 10% ethylhexylglycerin blend at 1% w/w is one of the most foolproof and reliable ways to preserve emulsions - the only time it's not performed adequately on its own was in a formula that contained a large amount of clay
    UK based formulation chemist. Strongest subjects: hair styling, hair bleaches, hair dyes (oxidative and non-oxidative) I know some stuff about: EU regulations, emulsions (O/W and W/O), toothpaste, mouthwash, shampoos, other toiletries
  • That combination is also potentiated by the addition of a chelant to the Formula.
    markfuller@microformulation.com Microformulation.com Microformulation Cosmetic Consulting provides Custom Formulations for both large Commercial accounts as well as smaller entrepreneurs. We can provide Naturally compliant Formulations under the NSF, NPA, Whole Foods and USDA Organic Certifications.
  • @Bill_Toge hope you find time for this question.
    how much clay is too much to use that as a preservative?  Clay % i mean :-) 
  • @Danedane that depends largely on what else is in your product, and how sterile the clay is

    also, when I said it didn't perform adequately, what I meant was that it worked, but the reductions in microbial counts during the challenge test weren't fast enough for it to pass - an additional preservative was needed
    UK based formulation chemist. Strongest subjects: hair styling, hair bleaches, hair dyes (oxidative and non-oxidative) I know some stuff about: EU regulations, emulsions (O/W and W/O), toothpaste, mouthwash, shampoos, other toiletries
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