Fixative for Essential Oils...

I have been trying to extend the working time of an essential oil blend in a lotion against mosquitos.  I have been working with Vanillin, (dissolved in ethyl alcohol) and it has been giving me all kinds of emulsion grief.  Just curious if anyone knew a good fixative for volatile essential oils (other than Vanillin)?  I am about to pull my hair out with the Vanillin.....But dang...it works, if I can just keep the emulsion together.  Added Carbomer in last two batches....and that seems to help (also use .2% X-gum and some stearic and propanediol).  Was advised that good old e-wax....was the best emulsifier for tough emulsions?  Had some Cyclomethicone in early batches...but removed from the last batch, wondering if that might challenge the emulsion?  But mainly looking to extend the useful life of my EO's, beyond 18 minutes.  :) 

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  • GraillotionGraillotion Member
    edited March 2020
    I have Benzyl benzoate on hand, but don't know the use rate for a leave on lotion.
    And I could get Glucam P 20, from one of my suppliers.
  • AvickAvick Member
    Hi Graillotion! 

    Here is the IFRA standard for benzyl benzoate: https://ifrafragrance.org/standards/IFRA_STD48_0161.pdf

    It sounds like you are making a product in category 4--I believe this website describes them correctly but not 100% sure: https://plushfolly.com/Information/Page-/-Category

    So, you have a pretty high max percentage that you can use--26.7%, I believe, which is way more than you would need.

    I'm also a fan of coumarin, which has a subtle, sweet hay scent and can be found as a natural isolate in powder form. When mixed with the essential oils, it does linger longer and also repels mosquitoes. :)

    It's what was responsible for the surprise off-label success of Avon Skin So Soft as a mosquito repellent. 


  • Thank you Avick, your answer was very helpful.  I had come across coumarin in my research, and after further review, my interest is perked.  Do you have any idea was the inclusion rate would be?  A quick scan of ebay/amazon shows about $8/ounce.  Not sure my regular (small) suppliers are going to carry this.

    Thank You.
  • You know there is more to it than simply adding a fixative. 

    The Carbomer is a good idea. It can be used as a film former in encapsulation. 

    There are patents describing the encapsulation of fragrances using Carbomer in water and a small amount of surfactant (CAPB) at 1%. The fragrance oil is added under heavy homogenization to form small particles which can then be filtered (some how). 

    You can use Cetyl Alcohol as a core material for your fragrance. Simply dissolve and cool very quickly. Usually a 3 to 1 ratio (Cetyl Alcohol to fragrance) is used. You can then add Carbomer at a 15-20% rate and activate it with some water under slow grinding. Think of wet granulation. I did this will some Orange EO and the scent is still very strong.

    Not sure how you would add granules to a lotion however. This process worked well with Carbomer, not so much odor retention with PVP (30)

    IPM added at 1-5%  of Fragrance Level
    Glucam-20 1-5 %  of Fragrance Level (I find this one personally tricky as it dulls the scent easily)
    Decyl Glucoside can also be considered a fixative according to some patents I read.

    My personal favorite, dissolve the oil in Aerosil 200 (Silicon Dioxide). It is an unbelievable fixative. I made anhydrous products which have been sitting in open air and the smell is still strong after 3 months or so. Similar products not using Silicon Dioxide lost scent after about a week.

    My only hesitation is where to add the Aerosil/Fragrance composition, oil phase or water phase. I have not concluded which is better. And when I try to read more lately my head hurts. lol
  • Avick , regarding the Benzyl Benzoate, do you know if this can be used as a sole solvent for Vanillin?  I had heard that BB and B Alcohol in a 50/50 blend was an effective solvent for Vanillin.  I would like to minimize the ingredients, so if BB by itself was a solvent, and ALSO gave me some 'fixative' aspects...that would be a stone that killed many birds at once.

    Love to hear your thoughts....or anyone else with some insight on the topic.

  • GraillotionGraillotion Member
    edited March 2020
    Cafe33 thank you for your insight.  Couple of q's....sometimes multiple modes of action...(example....several types of fixative) work synergistically...and sometimes it is just stupid repetition.  Regarding fixatives and essential oils.... would multiple fixatives be redundant, or synergistic? …. (I am sure the answer will include something to the effect of...depends how each works... So if you could list a couple that would work synergistically...that would be helpful... :) )


    Regarding Aerosil 200.... haven't done my long drawn out study yet....but in my 15 min preview....I saw no mention of 'fixative' as a feature.  I realize that products can be used in many ways... but would you consider it common knowledge/practice in the cosmetic industry... Aerosil 200 is being used as a fixative in leave-on products? 

    I also discovered on my workbench....I had PPG-20 Menthyl Glucose Ether.... Any thoughts on this product as a fixative? 
  • Glucam-20 is PPG-20 Methyl Glucose Ether. I have used it and it can get tricky as it dulls the scent. You have to start slowly.

    I have a synthetic Vanillia fragrance and the composition shows many different fixatives used. So they do work together, but its not something I really understand all that well. 

    You wont find too much info on Silicon Dioxide as a fixative for leave on products. I am not sure about that, my applications are almost exclusively wash off.
  • chemicalmattchemicalmatt Member, Professional Chemist
    Use triethyl citrate, best fragrance oil fixative around.
  • chemicalmatt, thanx for the comment...I did some searching and am interested in that.  Since I will be buying a small quantity (found a seller of small amounts, even the Natural version)…. But I did not find anything in regards to formulation....inclusion rate.  Typically when I add ingredients...I use % of total formula....so if you can give me some info on inclusion rate, please specify.... inclusion rate of entire lotion.... or percentage based on just the essential oils... 
    Thanx!
  • LuisJavierLuisJavier Member
    edited April 2020
    Benzyl alcohol is far better at dissolving vanillin than benzyl Benzoate. I’ve tested it out myself. 10% vanillin in benzyl Benzoate seems to be the maximum inclusion rate, and around 32-34% vanillin in benzyl alcohol. Both at room temperature in the UK. The only reason I see to use a 50:50 mix of both of these solvents is if you don’t want to use too much benzyl alcohol due to the restrictions in a category 4 application (fine-fragrance spray intended on skin). 
  • Use triethyl citrate, best fragrance oil fixative around.
    What do you think of C12-15 alkyl benzoate, as a fixative?  Certainly wouldn't hurt the lotion to add it, just didn't know if it brings anything to the table.....as far as fixatives go?

  • I am also using Hydrolyzed jojoba esters in another formula...and have heard it has some fragrance fixing properties....any thoughts on this?
  • FekherFekher Member, Professional Chemist
    @Cafe33 is the oil soluble in silicon dioxide? 
  • Cafe33Cafe33 Member
    Yes colloidal silicon dioxide will absorb oil fairly efficiently from my experience. My first test was to place some peppermint oil onto some Aerosil. I think I used something like 1g of Oil to 0.5g of Aerosil. It absorbed it fully and remained in solid state, powder was still "flowable". I left it in an open beakers for weeks, even well past a month and the smell was just as strong as day 1 (IMO). Keep in mind that it was Summer months, and the room Temp could climb to 30-31C.
  • Cafe33 said:
    Yes colloidal silicon dioxide
    Would this be considered .... leave on....skin safe?

  • PharmaPharma Member, Pharmacist
    Aerosil is also stomach safe. However, it's not too safe for lungs...
    We use it for example for capsules and sometimes also pharmaceutical creams.
  • Cafe33Cafe33 Member
    edited July 2020
    We used it in solid compressed products. It is a miracle compound for tablet pressing. You would add it to impossible to compress API's and watch the powder lose volume and get more dense as you blended the silicon dioxide. Not only does improve flow-ability of API, it also adds an element of cohesion to the mix. The product I was familiar with is Syloid 244. 

    And yes, it is terribly nauseous and dangerous to inhale. 
  • There is an patent available for encapsulation technique using fumed silica. I tried it but facing problem for the gelling step I used 0.5 gm SiO2 dispersed in 60 gm of water then adding fragrance oil. It does work but the next haven't been able to crack which involves further coating the silica with calcium chloride can anyone guide regarding this.
  • GraillotionGraillotion Member
    edited November 2020
    Cafe33 said:
    You know there is more to it than simply adding a fixative. 


    My personal favorite, dissolve the oil in Aerosil 200 (Silicon Dioxide). It is an unbelievable fixative. I made anhydrous products which have been sitting in open air and the smell is still strong after 3 months or so. Similar products not using Silicon Dioxide lost scent after about a week.

    My only hesitation is where to add the Aerosil/Fragrance composition, oil phase or water phase. I have not concluded which is better. And when I try to read more lately my head hurts. lol
    I think I will give the Aerosil 200 a look.... @Cafe33 do you have a use rate....and technique? Should I just make a slurry with only the EO's....? Or just toss the A200 into the general emulsion? Have you experienced any abrasiveness with Aerosil 200? I see there are finer version....but A 200 is cheaper.
  • Cafe33Cafe33 Member
    edited December 2020
    Hi, what is it that you are trying to do again? There are patents on using Silicon Dioxide as part of a perfume encapsulation system. Usually something like like 2-5% of the total system is used with the perfume consisting of 30% or so. 

    My experience: 

    Cafe33 said:
    Yes colloidal silicon dioxide will absorb oil fairly efficiently from my experience. My first test was to place some peppermint oil onto some Aerosil. I think I used something like 1g of Oil to 0.5g of Aerosil. It absorbed it fully and remained in solid state, powder was still "flowable". I left it in an open beakers for weeks, even well past a month and the smell was just as strong as day 1 (IMO). Keep in mind that it was Summer months, and the room Temp could climb to 30-31C.
    That is what I can offer. As for leave on skin products concerning abrasion, I do not know. My experience relates to oral use and rinse off hair products. I did make some oil gels using Aerosil with almond, Jojoba and natrasil oils if I remember, and there is some documentation through Evoniks that details percentages to use and viscosity of different oils. Maybe you can look into it by contacting Evoniks?  

    As for the rinse off products, 45-50% Aerosil use according to fragrance was definitely impressive. I think your testing range should be 10-50% based on the fragrance.   
  • Cafe33 said:
    Hi, what is it that you are trying to do again? There are patents on using Silicon Dioxide as part of a perfume encapsulation system. Usually something like like 2-5% of the total system is used with the perfume consisting of 30% or so. 

    My experience: 

    Cafe33 said:
    Yes colloidal silicon dioxide will absorb oil fairly efficiently from my experience. My first test was to place some peppermint oil onto some Aerosil. I think I used something like 1g of Oil to 0.5g of Aerosil. It absorbed it fully and remained in solid state, powder was still "flowable". I left it in an open beakers for weeks, even well past a month and the smell was just as strong as day 1 (IMO). Keep in mind that it was Summer months, and the room Temp could climb to 30-31C.
    That is what I can offer. As for leave on skin products concerning abrasion, I do not know. My experience relates to oral use and rinse off hair products. I did make some oil gels using Aerosil with almond, Jojoba and natrasil oils if I remember, and there is some documentation through Evoniks that details percentages to use and viscosity of different oils. Maybe you can look into it by contacting Evoniks?  

    As for the rinse off products, 45-50% Aerosil use according to fragrance was definitely impressive. I think your testing range should be 10-50% based on the fragrance.   
    As I am working on a mosquito repellent, I am only looking for a few hours of retention.  I did some trials, and yes silicon dioxide has an uncanny ability to absorb oil.  One dish was in a solid paste state (Grapefruit essential oil), one was at about a syrup stage, and of course had one that was just pure EO.  At 48 hours, I could not detect an enhancement of scent retention in the oils containing silicon dioxide.  So at this time I will not pursue this avenue.  Thank you for sharing your knowledge.
  • Which silicon dioxide did you?
  • Cafe33 said:
    Which silicon dioxide did you?
    Aerosil 200
  • Avick said:
    Hi Graillotion! 

    Here is the IFRA standard for benzyl benzoate: https://ifrafragrance.org/standards/IFRA_STD48_0161.pdf

    It sounds like you are making a product in category 4--I believe this website describes them correctly but not 100% sure: https://plushfolly.com/Information/Page-/-Category

    So, you have a pretty high max percentage that you can use--26.7%, I believe, which is way more than you would need.

    I'm also a fan of coumarin, which has a subtle, sweet hay scent and can be found as a natural isolate in powder form. When mixed with the essential oils, it does linger longer and also repels mosquitoes. :)

    It's what was responsible for the surprise off-label success of Avon Skin So Soft as a mosquito repellent. 


    Very interesting about the Avon Skin so soft! I grew up in Alaska where the state bird is the mosquito 😉 and we used that all the time because it smells so much better than other insect repellents and it works just as well. I never knew why, but now I do. Thank you!

    I have been thinking about making perfume and I am just starting to read about the different components. I have been using ethanol and fragrance oils which smell nice, but don't last very long. So I want to create my own fragrance profile. 
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