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How to mix 5-10% water soluble solid in petrolatum
Hi,
I am new to this, really appreciate your advice and guidance.
Currently trying to mix potassium sorbate and water soluble active (active originally in solid form) in petrolatum. Final product will only have 5-10% active in it. Active should be stable up to 70degree C (160 F)
What would be the best way to mix them and what is the mixer/emulsifier to use for my bench test?
BIGG Thanks in adv.
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5 Replies
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Option 1 - grind active and potassium sorbate into petrolatum, using no water. This makes what the pharma folks call an ointment. Due to the extremely high viscosity of petrolatum at room temperature, the best way to do this is with a three-roll mill (sometimes called an ointment mill).
There’s an awesome lab one here: http://exaktusa.com/dispersion-equipment/basic-models/trm-basic-exakt-50i/ This is from a different manufacturer, but it’s a good overview:Ross, the inventors of the 3-roll mill, also makes a (much larger) lab version:Option 2: Make a water-in-petrolatum emulsion. Any decent mixer/homogenizer can handle this, but it’s not a room-temperature process. -
For very small amounts, you could use a pigment muller to simulate the 3-roll mill:
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Hi Bobzchemist,
Thank you.As for making water-in-petrolatum emulsion, I presume we also need emulsifier don’t we? Or is there a way to avoid it altogether, yet still have a stable emulsion (considering that my water part may be as low as 10%)? (sound silly but just trying to get the trick of the trade - if any;) -
You will need an emulsifier for any amount of water unless you have extremely expensive ultra-high-shear equipment. Also, once you add water, you need good/strong preservatives. Without water, smaller amounts of simple broad-spectrum preservatives will do.
Please note that selling this commercially, at least in the US and EU, will require much safety testing, etc. -
Yes, safety and stability testing will be the next thing I will put my head into. May be posting more questions after that
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Thanks again Bobzchemist.
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