Stabilising watery emulsion

Hello
I am new here. Hopefully my question isnt too  basic.

I am making a sprayable O/W emulsion using 10% natural oils (equal parts Macadamia/Almond/Argan).  I have used the Polysorbate/Sorbitan Oleate emulsifier system, and I do understand the HLB sysem. I have also used a few extra drops of Laureth 4.
The liquid is lovely for day 1, after about 30hrs it seperates and the oil still floats to the top albeit still sort of emulsified.
I have heated the oil and water phase to 40 deg C, and used a stick mixer to blend. I found increasing the emulsifiers made the spray feel soapy on my skin and I want it to feel like a liquid lotion and not sudsy at all.
My question is how can I get this to stabilise and stay emulsified?  Is it a choice of emulsifier, or the method of how I make it?  I would like to bottle it in a clear bottle without the need to shake it up every day,

Any advice would be a help

Thanksyou  CB

Comments

  • Bill_TogeBill_Toge Member, Professional Chemist
    edited August 2015
    the HLB system is only one of the factors that determine emulsion stability

    firstly, you need to ensure your emulsifiers and oil are chemically compatible with each other; if they're not, then they won't mix or stay mixed at all, regardless of what the HLB system says

    secondly, you need to ensure your emulsified oils cannot physically separate from the water phase, or can only do so with great difficulty - and this is where your problem lies

    because you're making a thin, sprayable product, what you need is a rheology modifier that gives the formula some zero-shear viscosity (i.e. stops the droplets within the liquid from moving while at rest) - in a thicker product such as a cream or a paste, this can be achieved with a judicious choice of emulsifiers and oil-phase ingredients

    if you want to keep the overall viscosity low, then Laponite clays and/or gellan gum work well

    and your question is not basic at all - there are lots of otherwise knowledgeable people within the industry who don't understand how emulsions work!
    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
  • BobzchemistBobzchemist Member, PCF student
    I have to suggest the pemulens again - TR-1 was designed to fix this problem.
    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."
  • Thank you both for you comments.  I have been reading all the helpful info on emuslions through this forum. 
    Thank you Bill_Toge for the info re rheology modifier.  I will go and study this for a while. I do have some gums that I didnt think to try. I will have to experimetn more once Ive read a lot!

    Thankyou Bobzchemist, I will buy som of the TR-1 and have a go with it.


  • manstramanstra Member
    edited August 2015
    From my personal experience I used this following system that delivered the necessary results
    I will not give exact percentages as this will change according to HLB and the kind of oils you use

    - Tween 20
    - Peg -40 Castor oil Hydrogenated
    - Glycol Distearate

    Watery emulsions tend to seperate sometimes when temperatures are elevated (above 40 Celcius) or during the cooldown phase. If destabilization happens, remix at room temperature (around 25C)

  • Thank you manstra. I will have a play with those ingredients, I think I have some here.

    No further news re the Pemulen, waiting for it to arrive. Then I will post my results. Thanks again for the advice! Even getting pointed in the right direction to research is fantastic and very appreciated
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