Is this preservative system enough? using tap water

Hi, my current liquid shampoo formulation for dry hair contains SCS, SCI, coca hydroxysultaine, maltodextrin, salt, coconut oil (1%) and cocoa butter (1%). Total Active Surfactant Matter is roughly 8%.

My PH is under 4.5, and the shampoo gets used within 3 months max (on average gets used up in 1 month). 

1. Would Benzyl Alcohol-DHA at 0.8% be sufficient in preserving my liquid shampoo? Some chemists on here recommended adding Sodium Benzoate at 0.4% to protect against mold, but I also read it could irritate skin. And my skin is very sensitive.

2. If I use tap water to make my shampoo (I don’t have distilled water on hand), would these preservatives be sufficient in killing the tap water bacteria?

Forgive my ignorance..any advice appreciated! 


Comments

  • PhilGeisPhilGeis Member, Professional formulator
    Probably not - tap water typically includes pseudomonads - esp. P . aeruginosa.    Chloromethylisothiazolinone is the most commonly- used primary preservative in surfactant products.  Suggest use with Na benzoate and EDTA.   
  • Thank you, wanted to mention that I’d like to use some of the more eco-friendly/eco-certified preservatives like Benzyl Alcohol-DHA, potassium sorbate. The chloromethylisothiazolinone honestly sounds a bit intimidating..
  • PharmaPharma Member, Pharmacist
    Better use potassium sorbate, not sodium benzoate against mould/yeast.
    With one to three months shelf-life, sufficient preservation shouldn't be too difficult to achieve.
    If you can't/won't run challenge tests, combine your current preservative system with a benzoate/sorbate combo (or anisate/levulinate) and, very important, EDTA or another chelate (eco-friendly GLDA or natural phytate) and you should be more than fine.
    Apart from that, 2% oil in 8% surfactants... does it even clean? I mean, if you're trying to be eco-friendly, omit the oils and maltodextrin (use these as leave-in conditioner) and reduce the amount of surfactants (this also means less bug food and hence easier preservation) ;) .
  • edited January 11
    @Pharma
    Thank you, so are you saying:

    Assuming I use faucet/tap water to make my shampoo, I should probably be good with a preservative system against bacteria and mold if I use:

    Benzyl Alcohol-DHA + Potassium Sorbate

    And secondly, would I HAVE to use GLDA? 
  • PhilGeisPhilGeis Member, Professional formulator
    edited January 11
    Is this for personal use?  Didn't see 1-3 months self life mentioned.   Are you heating your "tap water" or is this cold process?
    Reducing "bug food" is not going to mean you need less preservation.  The common contaminats of shampoos (esp. cepacia)  can grow quite well in distiled water.

    I've seen some degree of synergism with benzyl alcohol and benzoate but you will need a chelator.  The cosmetic market has largely gravitated to benzoate over sorbate, esp. in the surfactant context.

    Historically orgniac acids, with parabens, were the go-to preservatives.  The development of cold-process, surfactant-based shampoos back in the 1930's found them  pretty useless, and the industry shifted to formaldehyde with L'Oreal's Dopal and P&G's Drene.

    Is "eco-friendly" your marketing claim?
  • GraillotionGraillotion Member
    edited January 11

    And secondly, would I HAVE to use GLDA? 
    GLDA is a chelator.  Not really a preservative.  That being said, a chelator GREATLY enhances preservation, hence it is part of EVERY conversation regarding preservation (preservation enhancer might be a good description).  Distilled water is low in things that need to be chelated.  Tap water....probably loaded.

    What country do you live in...that does not have ready supplies of distilled water?

    Do you have a dehumidifier?

    Assuming.... ONLY personal use, as you could not state how quickly it is used, if sold!
  • At a minimum, I would boil the water first.
  • PhilGeisPhilGeis Member, Professional formulator
    pH (via pKa) is a controlling factor for organic acids - benzoic and sorbic - efficacy.  In combination with some surfactants (incl those commonly used for shampoos etc.) , the effective benzoic acid pKa and pH range for efficacy for  is greatly increase - approaching neutrality.    This has not been observed fior sorbic acid.
  • @PhilGeis ok, so then I’ll try Sodium Benzoate, seems to be the popular rec on this board! Separately, do you think my use of maltodextrin makes it a greater “bug food” source, therefore might I need to increase my percentage of preservative?

    Thank you in advance for your expertise! 
  • @Graillotion living in the US. I will use boiled water and a chelator as suggested. I’m worried the maltodextrin in my formula might make it a more enticing environment for bacteria/whatnot...would I need to use a greater amount of preservative to counter that? Thank you in advance. 
  • ozgirlozgirl Member, PCF student
    Distilled water can be obtained quite easily from most grocery stores/supermarkets and also from places like Walmart. 

    Tap water can cause other issues than just with preservation due to the calcium, magnesium, sodium ions present. So why not avoid it if you can.
  • GraillotionGraillotion Member
    edited January 14
    I live in Hawaii...where everything cost 2X...

    Hawaii Target and WalMart Price for distilled water: $1.27 for 1 gallon.

    I can only imagine how cheap it is at your place.

    Keep in mind....preservation is not just about what slips in during production....but what gets in as time goes by.  That is why boiling water is somewhat irrelevant. 
  • I used to use benzoyl alcohol and DHA at %1 with %0.1 edta and it was enough for a few months preservation
  • PhilGeisPhilGeis Member, Professional formulator
    @PhilGeis ok, so then I’ll try Sodium Benzoate, seems to be the popular rec on this board! Separately, do you think my use of maltodextrin makes it a greater “bug food” source, therefore might I need to increase my percentage of preservative?

    Thank you in advance for your expertise! 
    Assume you mean Na benzoate with benzyl alcohol?  I'd add EDTA and would not be that concerned that maltodextrin is bug food as much as its effect on preservatives.   Cepacia can grow in distilled water.
  • PhilGeisPhilGeis Member, Professional formulator
    Please heed Graillotion's comments.    The objective oif preservation per FDA and EU is to protect in use.   A preservative system good "enough for a few  months" is like not enough.
  • GraillotionGraillotion Member
    edited January 15
    Thank you Phil.

    Another way I like to look at these scenarios, and maybe this will help those just starting out.... Is understanding what a challenge test is.  Let's just live in the land of unicorns and candy canes for a moment, and say we created a bug free product.  Then we sent this 'pristine' product off to be tested.  If you are not familiar with the process....essentially they pollute (inoculate) your pristine product with a number of nasties.  The object of the game is for your product to eliminate these nasties, and return to the original pristine state. 
    So if your only focus is on creating something initially without bugs...you have totally missed the point.  Yes...that is a wonderful starting point, but the real game is a products ability to fend off bugs that are introduced over the expected life of the product.
  • PhilGeisPhilGeis Member, Professional formulator
    PhilGeis said:
    Please heed Graillotion's comments.    The objective oif preservation per FDA and EU is to protect in use.   A preservative system good "enough for a few  months" is like not enough.
    Is LIKELY not enough.  I'm not in high school.
  • PhilGeis said:
    @PhilGeis ok, so then I’ll try Sodium Benzoate, seems to be the popular rec on this board! Separately, do you think my use of maltodextrin makes it a greater “bug food” source, therefore might I need to increase my percentage of preservative?

    Thank you in advance for your expertise! 
    Assume you mean Na benzoate with benzyl alcohol?  I'd add EDTA and would not be that concerned that maltodextrin is bug food as much as its effect on preservatives.   Cepacia can grow in distilled water.
    What might be maltodextrin’s effect on preservatives? 
  • Thank you Phil.

    Another way I like to look at these scenarios, and maybe this will help those just starting out.... Is understanding what a challenge test is.  Let's just live in the land of unicorns and candy canes for a moment, and say we created a bug free product.  Then we sent this 'pristine' product off to be tested.  If you are not familiar with the process....essentially they pollute (inoculate) your pristine product with a number of nasties.  The object of the game is for your product to eliminate these nasties, and return to the original pristine state. 
    So if your only focus is on creating something initially without bugs...you have totally missed the point.  Yes...that is a wonderful starting point, but the real game is a products ability to fend off bugs that are introduced over the expected life of the product.
    Thank you Phil.

    Another way I like to look at these scenarios, and maybe this will help those just starting out.... Is understanding what a challenge test is.  Let's just live in the land of unicorns and candy canes for a moment, and say we created a bug free product.  Then we sent this 'pristine' product off to be tested.  If you are not familiar with the process....essentially they pollute (inoculate) your pristine product with a number of nasties.  The object of the game is for your product to eliminate these nasties, and return to the original pristine state. 
    So if your only focus is on creating something initially without bugs...you have totally missed the point.  Yes...that is a wonderful starting point, but the real game is a products ability to fend off bugs that are introduced over the expected life of the product.
    Thanks for the easy to understand explanation! very much appreciated. 
Sign In or Register to comment.