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Quest for the Right Preservative part II: the struggle continues…
Actives like botanicals, pH, packaging material (plastics), nonionic surfactants and interactions with actives or excipients , too irritable…
It seems like every time I think I have the right preservation for a certain concoction, there is always something that gets in the way of the preservative…
But let’s not get desperate, so I hope I can get some help with the following questions.
- I see phenoxyethanol, benzyl alcohol or parabens being used in a lot of stuff where also nonionic surfactants are being used.
I read that even 3% of polysorbates can already inactivate your preservative. How the hell do they keep it right with those combinations? Like a moisturizer with cetyl alcohol aswell as phenoxyethanol. Do they use higher concentrations of the preservative? - Most of the products are kept in plastics. But there are lots of interactions between them.
Benzyl alcohol by polyethylene, sorbic acid/sorbates by plastics (polypropylene, PVC and polyethylene, phenoxyethanol by pvc plastic, cellulose based excipients.
Can I really keep on using my standard plastic airless dispensers?
I don’t have a cosmetic business, so I can’t check my preparations for microbial growth. Instead I try to emulate already existing formulations, only use it for max. 3 months or so. I add glycerin and other polyols and a silicone (cyclopentasiloxane), no bugfood like oatmeal, honey etc, no jars but dispensers, keep it in the fridge, work as clean as possible (disinfect packaging, erlenmeyers, spoons etc., no bare hands but gloves when weighing and preparing), boil the demi water I use for about 15-20 mins.
These are the preservatives I have right now that I can get my hands on (suppliers are scarce here) I use combi’s to try to be as broad spectrum as possible
- benzyl alcohol ;
_ dehydroacetic acid;
- phenoxyethanol;
- potassium sorbateAnswers on questions above + tips/advice: very welcome.
- I see phenoxyethanol, benzyl alcohol or parabens being used in a lot of stuff where also nonionic surfactants are being used.
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26 Replies
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What is your Ph?
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polysorbate 60 and 80 reduce the efficacy of preservatives at high levels, but this is not generally true of non-ionic surfactants
also, what’s your source for preservatives and plastics interacting?
in my experience the only things likely to attack plastic are strong oxidising or reducing agents (peroxide, thioglycolate salts), or organic solvents
and personally, I’d avoid potassium sorbate, as it’s terrible for turning liquid products yellow/brown over time
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@DRBOB@VERDIENT.BIZ
Between 3.5 and 5.5 (exfoliants and vitamin C serum 3.5, moisturizers between 4.8-5.5).@Bill_Toge
This is the source I get most of my information on preservatives on, also about the plastics.
If you read that, you get the feeling you can’t use anything.So if I use, like 8% E-wax (glyceryl stearate + PEG-100 stearate) and 2% cetyl alcohol, it is still ok to use phenoxyethanol or benzyl alcohol in normal amounts? And what about PEG-40 HCO?
About the potassium sorbate: how long does it generally take before it turns yellow/brown? I’ll use what I have now and then switch to another for mold/yeast. Thanks for the warning!
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How long does it generally take before it turns yellow/brown?
In my experience not less than 3 - 4 months. -
@Belassi,
Thanks. Will not be a problem for me, because the quantities I make are gone within no more than 3 months. -
If you need to get rid of discoloration use 1% benzyl alcohol-good compatibility with PVC and PE (low and high density)
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@Doreen81:
You really have nothing to worry about given the preservatives you have listed in your original post, particularly if you are using airless containers and given the pH end point of your products under pH 5.5.
Benzyl Alcohol (88%) + Dehydroacetic Acid (8%) + Glycerin is a well-established commercial preservative that is ECOCert.
Phenoyxethanol and Benzyl Alcohol are relatively interchangeable and have very similar chemical structures, but Benzyl Alcohol can be an allergen and can also cause discoloration over time.
So, if you wanted to use:
Phenoxyethanol (88%) + Dehydroacetic Acid (8%) + Potassium Sorbate (4%)
as a base all-around preservative, you’d be in good shape, particularly keeping your pH under 5.5 and using airless containers … just use it at 1%.
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I found a major problem with dehydroacetic acid. It reacted with the potassium glycrrhizate in our high-end product, precipitating out the insoluble form. It’s far too chemically active for my liking.
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I never found an all round “one size fits all” preservative when I was working.
Each formulation was assessed and a suitable preservative/preservative blend selected to suit. The whole mix was subjected to comprehensive testing for effectiveness of the preservative system as well as physical and chemical stability of the product.
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@DRBOB@VERDIENT.BIZ
If you need to get rid of discoloration use 1% benzyl alcohol-good compatibility with PVC and PE (low and high density)
Thanks! Will keep that in mind.
@MarkBroussard
Thank you! I’m glad to read I don’t need much dehydroacetic acid in the combination you mentioned in a 1% solution of all three. It has a very chemical, medicinal smell.I found a major problem with dehydroacetic acid. It reacted with the potassium glycrrhizate in our high-end product, precipitating out the insoluble form. It’s far too chemically active for my liking.
Hmm another interaction… I will keep this in mind, since I like to use licorice root and I’m looking for this easy soluble and colorless potassium salt, but can’t find it here yet.
I already helped to convince a supplier here to take oat extract in their assortment. Hopefully they will see the need for potassium glycrrhizate aswell. Both oat extract and licorice are multifunctional and if I see the whole list of fairydust ingredients that they do sell… it’s beyond me. It seems that a lot of customers rather buy fancy stuff like colloidal gold for example than stuff that really works.Each formulation was assessed and a suitable preservative/preservative blend selected to suit.
This would indeed be the ideal situation…
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Each formulation was assessed and a suitable preservative/preservative blend selected to suit.
This would indeed be the ideal situation…
Not just an ideal situation, an essential one!
The costs involved if anything goes wrong are astronomical.
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Not just an ideal situation, an essential one!
The costs involved if anything goes wrong are astronomical.I don’t sell my stuff, it’s for own use. And I don’t make large quantities, generally I use it within 2-3 months, except for the vitamin C serum (Skinceuticals emulation), which is about 3 weeks.
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Bugs don’t respect how quickly your stuff may be used. For your own safety you should ensure that ALL of your concoctions are adequately preserved.
Remember that a number of micro-organisms can replicate ever 20 -30 minutes so 2-3 months or even 3 weeks is a very long time in the world of micro-life.
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Seriously, does anyone really think that a 1% Phenoxyethanol, Dehydroacetic Acid & Potassium Sorbate combination at pH < 5.5 in an airless container stored in the refrigerator is not going to adequately preserve Doreen’s product which is purely for personal use over a 3 month period?
Doreen, you should be just fine on preservation.
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Seriously, does anyone really think that a 1% Phenoxyethanol, Dehydroacetic Acid & Potassium Sorbate combination at pH < 5.5 in an airless container stored in the refrigerator is not going to adequately preserve Doreen’s product which is purely for personal use over a 3 month period?
Doreen, you should be just fine on preservation. ACTUALLY ITS OVERKILL
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@MarkBroussard
Seriously, does anyone really think that a 1% Phenoxyethanol, Dehydroacetic Acid & Potassium Sorbate combination at pH < 5.5 in an airless container stored in the refrigerator is not going to adequately preserve Doreen’s product which is purely for personal use over a 3 month period?
Doreen, you should be just fine on preservation.Thank you, I’m glad to get this (re)assurance from a microbiologist!
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I was not suggesting that there was anything wrong with Doreen’s preservation system, merely that a preservative that is shown to be effective in the product under scrutiny must be used.
The negative comments by others re dehydroacetic acid and potassium sorbate might just possibly lead to the thought train of “Oh, let’s not bother with these difficult materials” and, instead of replacing with other preservatives which can be proven to suitable (in all respects) they are omitted completely thus leaving a mix that is prone to contamination.
The “personal use” phrase doesn’t count for anything. Contaminant bugs don’t know this and will readily keep growing and reproducing wherever nutrients are available.
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Doreen asked a simple question … and it has a simple answer:
1% Phenoxyethanol + Dehydroacetic Acid + Potassium Sorbate will provide adequate preservation of virtually any cosmetic formulation she develops if she keeps the pH below 5.5.
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Mark’s comment: “1% Phenoxyethanol + Dehydroacetic Acid + Potassium Sorbate will provide adequate preservation of virtually any cosmetic formulation she develops if she keeps the pH below 5.5.”
Unfortunately I tried this and it failed preservative testing and my pH was 5.1 in airless pump. What can I do?
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@lotionmaker
Did you sterilize/disinfect equipment, erlenmeyers, spoons, what kind of water did you use (distilled, purified), did you add a chelating agent, ingredients like clay, what kind and % of surfactants, keep it in the fridge or in a damp hot bathroom, with other words:You need to give a lot more information if you want people to help you on here.
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Hi Doreen81, Thank you. yes I did sterilise. I used distilled water and added a chelator. No clay. Used SLES and CAPB. Stored in 15-20 celsius. Not humid.
Mark’s comment: “1% Phenoxyethanol + Dehydroacetic Acid + Potassium Sorbate will provide adequate preservation of virtually any cosmetic formulation she develops if she keeps the pH below 5.5.”
It is a pity what he said did not work for me. It is ok I can go back to my old synthetic blend as that will be stronger and be less irritating. It worked before. Thank you. -
@lotionmaker
I would advice you to start a New Discussion where you explain your own exact problem as detailed as possible. That way you give people the chance to think along with you and together you can find out what the problem has been in your specific situation. Preservating can be tough, good luck! -
Thank you again Doreen. It’s OK as I was just experimenting with more natural type preservatives. I do have a problem with irritation with the blend Mark suggested anyway so aside from it not preserving my formula I could not use it anyway. I was fine with my old synthetic blend which preserved my formula well, except the time I added collodial oats and it moulded. But this time I leave the oats out and all is fine.
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The blend of preservatives that was suggested by Mark is strong on moulds. The reason why he suggested this, was because I gave the preservatives I’m having at home right now, there are lots of others to choose from. And like johnb pointed out, there is no ‘one size fits all’. This was merely to help me out, in my situation. That’s why I advice you to start your own discussion on here, I’m not an expert and there are so many other preservatives than the ones I have at home.
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I think I took the words “ WILL provide ADEQUATE preservation of virtually ANY cosmetic formulation she develops” too literally!
Yes you are totally right there is no one size fits all preservative. I think I saw Microformulations mentioning that too in the posts here. He seems to be very knowledgeable in this area from what I read.
So sorry for hijacking your post. If I need help I will of course start a new thread but as I said I am fine for now.
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