Preservatives-which one?

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    Hello all,
    New here. Just discovered Humblebee and Me maybe 2 months ago. I have a question about which preservative people would recommend. I know I need one but am not sure which to choose. I’ve looked at info and been a bit overwhelmed as to which one to pick. Are there ones you’ve tried and liked? Are there ones that have failed or been difficult to work with?

    Looking over Humblebee I want to make at least half of the things on here if I could but my time and money are limited. I do want to make lotions, sugar scrubs, face cleansers (some are cleaning oils and don’t need a preservative), skin creams, and hair conditioners.

    Again I know there is a lot of info out there but I end up wanting to analyze every speck of info and end up being paralyzed about making a decision. So any words of wisdom are welcome.


    Hi Artistalisa,

    From the research I’ve made when I first encountered this same exact question, these are the things you should know and consider when DIYing and using water environment in you product:

    1. There are generally two families of microorganisms (MO) capable of proliferating in a product containing water: bacteria and fungi. The bacteria is generally divided to Gram positive (+) and Gram negative bacteria. And the fungi, which is of concern to us is mold and yeast.

    2. You can generally divide products by their Water Activity, Aw.
    The higher the Aw of your product, the more microorganisms can proliferate in it.

    Here are some example of the cosmetic products you’ll make, their Aw, and the types of microorganisms that love to live with this Aw:
    – 1.00 – Distilled water – All MO.
    – 0.96-0.99 – Shampoos, emulsions, liquid make-up, creams, lotions, make-up removers – All MO.
    – 0.90-0.95 – Shampoos, hair conditioners, creams, lotions, mouthwashes, some toothpastes – Several Gram (-) and mostly Gram (+) bacteria, mold and yeast
    – 0.80-0.89 – Most toothpastes, some soap bars, lipsticks, creams – Gram (+) bacteria, molds and yeast.
    – 0.70-0.79 – Some toothpaste gels, some soap bars – Halophilic bacteria, mold and yeast.
    – 0.65-0.69 – Antiperspirants – Osmotolerant yeasts
    – Below 0.6 – Powder products – None.

    You will not be able to measure Aw at home, as you’ll need specific apparatus for this kind of measurement. This numbers here are just to give you an idea what kind of families of MO you’ll grow in each of you products if you won’t use a preservative.

    3. Besides using preservatives, a slight reduction in the Aw of a cosmetic formulation can be helpful in preventing the growth of contaminating MO that are introduced during consumer usage. There are some ingredients that decrease Aw by absorbing water from the formulation and making it unavailable for use by MO, such as:
    Amino acids, glycerol, butylene glycol, propylene glycol, dextrins, xanthan gum, sodium chloride, and ethanol.
    Some of these ingredients you often can see in some of yours commercial products

    – High concentration of sugar can also decrease the Aw of a formulation (e.g. honey or jams, which can stay good for years without any preservatives), but you don’t really want so much sugar to you products, as it’ll become very sticky, very soon.

    4. pH
    Most microorganisms are able to proliferate at a pH value that is between 4.0 and 10.0 (bacteria pH 5.5-8.5, fungi pH 4.0-6.0). If a product formulation has a pH below 4.0 or greater than 10.0, there may be no need to include a preservative (e.g. vinegar or bleach). The low or high pH formulations are able to prevent microorganisms from either proliferating or surviving in them for the long term.

    So now that we know a bit about MO, let’s talk about preservatives.

    Currently there is no one molecule that can target all types of bacteria and fungi. In order to protect the product from every type of MO, a combination of molecules is used. The industry of preservatives basically compete who’ll get the best combo.

    When I understood that I have to use a preservative, I thought, “well, ok, I’ll just buy the Liquid Germall Plus that Marie uses”, she works with it for years for personal use, so it’s probably good enough for a DIY beginner as I am. And then I couldn’t find it anywhere in my country, and the price of shipping from US or Canada is just too high. So first I was avoiding water containing products, while I was doing my reading. There are just too many preservatives out there, and I did not want to risk my health or health of my friends and family.

    So here’s my approach to the subject of choosing a preservative. It is very subjective, but I would like to think that it is science based enough for my uses, and if there are people here, which disagree with my notions and considerations, please share your wisdom with us. It is an important subject.

    First, all the preservatives are very harsh molecules. You’d need only about 0.5-2.0% of your product to be a preservative (here some common preservatives and their usage levels), which means they are very strong.

    For this reason, many countries have they regulatory restrictions regarding preservatives. The United States has the fewest regulations of preservatives in the world (they only prohibit some preservatives, no pre-approval or positive list exists), so it’s logical to look at Japan and EU to see which preservatives are permitted in their markets, as a way to start the quest of finding the best global system, which will satisfy you.

    Here are some of permitted preservatives by EU and Japan, with the Japanese regulations:

    Preservative – Maximum concentration for all cosmetics
    Benzoic acid and salts – 0.2 as acid, 1.0 as salts as total
    Salicylic acid and salts – 0.2 as acid, 1.0 as salts as total
    Sorbic acid and its salts – 0.5 as total
    Para acid and its salts and esters (parabens) – 1.0 as total
    Dehydroacetic acid and Salts – 0.5 as total
    Phenoxyethanol – 1.0

    Some preservatives are considered safe only in Rinse-off products, such as:

    Preservative – Max. conc. in Rinse-off-no MM (mucous membrane)
    Imidazolidinyl urea – 0.3 with warning
    DMDM hydantoin – 0.3 with warning
    Methylchloroisothiazolinone (MCI) and methylisothiazolinone (MI) – 0.1

    Warning – Should not be used by infants or by people who are hypersensitive to formaldehyde.

    Here is the Antimicrobial Activity of some of these preservatives:

    Preservative – Spectrum of antimicrobial activity
    Benzoic acid – Fungicidal but has some activity against bacteria
    Salicylic acid – More active against fungi, but has better antibacterial activity than benzoic acid
    Parabens – Active against fungi and gram (+) bacteria. Has weak activity against gram (-) bacteria
    Phenoxyethanol – Active against gram (-) bacteria; weak against fungi
    MCI/MI – Has a broad spectrum of activity against bacteria and fungi

    You can see that, although MCI/MI has a broad spectrum of activity against bacteria and fungi, it is permitted only for Rinse-off products in Japan (and by the way not allowed in Germany at all).

    In addition, certain ingredients in your product can neutralize the antimicrobial activity some preservatives.

    Here are some examples of Preservative Neutralizing Agents:

    Preservative – Neutralizing agent
    Parabens – Lecithin, polysorbate surfactants, polysorbate
    Organic acid preservatives – Nonionic surfactants
    Formaldehyde – Protein, gelatin, sodium sulfite, histamine

    And there are other considerations as preservative solubility and its pH stability. For example, parabens have good antimicrobial activity at neutral pH, but the optimum activity is at an acidic pH and at pH greater than 8.0 they will dissociate to salt form.

    So lets look at Liquid Germall Plus.

    INCI is: Propylene Glycol, Diazolidinyl Urea (DU), Iodopropynyl Butylcarbamate (IPBC)

    DU targets mostly the gram (+/-) bacteria and some fungi, and IPBC targets mostly fungi and some bacteria. So together they cover the whole spectrum of MO. Propylene Glycol is added to decrease the Aw. It is effective over broad pH range 3.0 – 8.0, and safe for Leave-On and Rinse-Off products at 0.1 – 0.5% usage level. Both DU and IPBC are not neutralized easily, and the only disadvantage is that IPBC has temperature tolerance of below 40 Celsius (DU has temperature tolerance below 60C), so you have to add it when your product reached room temperature.

    Based on this information, I would suggest using Liquid Germall Plus.

    If for some reason you can’t find Liquid Germall plus (like your humble author here), I would suggest finding one preservative for Rinse-Off products and one for Leave-On products, taking into consideration all the aspects above (neutralizing agents, pH, water activity, solubility and so on).

    But even with a good preservative in hands, you generally shouldn’t use you homemade products, which contain water, for more than a month. This is because your work environment (which I guess would be a kitchen?) is not lab sterile, and I guess you are not planning to test your products for long usage, so you can’t really be sure that after a month or more, your product is still safe.

    Hope this was an interesting read 🙂

    Orth, S. D., Kabara, J. J., Denyer, P. S., Tan, K. S. (2006). “Cosmetic and Drug Microbiology”. CRC Press
    Rieger, M. M. (1997). “Surfactants in Cosmetics Surfactant Science Series”, V. 68. CRC Press


    I have a preservative question. I saw a product sold on Etsy (a small business & home crafters selling site) here in the States. It’s called Long Hair Don’t Care and it’s a conditioner. The maker was preserving it with acetic acid (a food preservative, from what I can tell) and aspen bark extract, which does not recommend for use on its own. Would the combo of these two ingredients properly preserve a hair conditioner? If I remember the ingredients correctly, they were water, BTMS 25, Abyssinian oil, jojoba oil, and some essential oils. I did not think that it would be a good preservation system, but wanted to get y’all’s opinions.


    Oh wow Totoro! AWESOME! I may not always say it or have the knowledge to fully understand what you are saying, but I really do appreciate your posts. Loving this thread topic about preservatives as the break down for various ingredients and which preservative would work better is amazing!!! I’m currently gathering information for a future blog post about preservatives and their importance, and this helps me to better understand what they are all about!

    , you mentioned that a few months ago you found Marie’s blog and are wanting to find a preservative to use. I personally like and prefer Liquid Germall Plus as it is a broad spectrum preservative. As Totoro mentioned, it does has one disadvantage that sometimes does my head in. You can only add it at temperatures below 40C. Good luck creating!


    I use Liquid Germall Plus and Germaben II. I have some Phenonip too that I use when I’m making infusions in water. I will preserve the infusion with that, then when I add whatever amount of infusion I need for my recipe, I preserve the whole recipe with LGP. That has worked out really well since I know infusions are basically bacteria buffets. Haha

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