Stirrer for O/W lotions

Hello All,

I am considering buying an overhead stirrer and need an advice where to start (specifications). Formulating skincare is a hobby for me and I can't invest several thousand dollars in a stirrer, however using a stick blender is not an option as it can't mix ingredients like sodium carbomer or silica powder. Also, some polymers like Aristoflex form a lot of air bubbles when mixed with a stick blender. The maximum batch size I make is 400 ml (from 100 to 400). I only make oil in water lotions (no pomades or very thick products). Can someone advise what would be the best option for such small batches? Or at least what specifications it should have (viscosity and speed?).

Thank you in advance!

Comments

  • Bill_TogeBill_Toge Member, Professional Chemist
    edited August 2018
    overhead stirrers are no good for lotions, they don't generate enough shear

    can you adjust the speed on the stick blender you have?
    if not, get a variable-speed stick blender and run it a speed that will circulate the batch effectively, and is slow enough not to introduce an excessive amount of air into it
    UK based cosmetic chemist with 13 years' experience at the bench. I've worked with pretty much everything apart from pressed powders, soap, solid lipstick and aerosols.
  • Thank you very much @Bill_Toge. I am currently trying to adjust a stick blender (remove the head) so that it creates a vortex. Let’s see if it works.
  • BelassiBelassi Member, PCF student
    If you don't want to buy an overhead stirrer, then you can easily enough work around by (eg)
    1. Not using a stick blender on sodium carbomer. You can use one on pre-neutralised carbomer eg. carbopol ultrez-20 and then neutralise after adding all the other ingredients.
    2. For polymers and similar you could simply mix by hand with such small batches. Here of course, in Mexico, we are completely unregulated, so I use two teams of 6 Central American slaves on the main hamster-wheel so as to rotate the modified cement mixer. 
    Cosmetic Brand Creation. Concept to name to IMPI search to logo and brand registration. In-house graphic design inc. Pantone specs. Cosmetic label and box design & graphics.
  • @Belassi the problem is, it doesn’t matter if you mix Aristoflex manually or with a kitchen stick blender it bubbles like a surfactant. Sepinov is slightly better but still incorporates air (both manually and stick blender). Regarding Sodium Carbomer, it is preneutralised, but the cool things about it is that it can be added in the end of the formulation to control viscosity (instead of hydrating it separately what I do now), so I wish I could use it like this. Also silica powder doesn’t mix manually. I am ready to invest in a stirrer, but since I am not a professional I don’t understand what is the cheapest sufficient option for such small batches. And also I would reeealy want to keep it within $1,000.
  • :D  @Belassi 2 X 6 slaves. Way to go. Sadly we have a very strict labour framework here in ZA. I will end up in jail so quickly my head will spin. 
  • Sometimes I think I’m reading posts just to see what @Belassi will say?. 
  • Chemist77Chemist77 Member, PCF student
    @Colorfuljulie oh we all do, can't have laughing gas but thank God @Belassi is there ??
  • So I ended up breaking my stick blender. Ordered another one with variable speeds, not sure it will change anything though. All overhead stirres below $1,000 are for low viscosity products..
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