PEG-40 hydrogenated castor oil, but I haven't had time. But holiday time means free time, so I had a chance to play with this product to see how it solubilizes fragrances!
I bought mine at Voyageur Soap & Candle, but you can find it at many retailers. And remember, I mention this as help to finding this ingredient, not because I've been paid to say nice things! And it should be a thicker, more gooey looking semi-solid, but it's hot in my workshop, so you're seeing a liquid here!
What is PEG-40 hydrogenated castor oil? It's a non-ionic surfactant that behaves as a foam booster and solubilizer of oils in water based products. (Unlike some other solubilizers, it won't suppress foam. Yay!) It can be used in the heated phase or the cool down phase of a product at up to 100%.
PEG? This a polyethylene glycol ester, which is an ester that has undergone a reaction with polyethylene glycol to create an ester that is water soluble and might behave as an emulsifier. This process is called ethoxylation and is an industrial process in which ethylene oxide is added to a fatty acid or fatty acid alcohol, and in the end non-ionic surfactants are produced. Surfactants have a hydrophilic (water loving) head and a lipophilic (oil loving) tail, which means they can help emulsify themselves or other oil based ingredients we might want to include in our water based products.
hydrogenated? Hydrogenation is the process of breaking those double bonds in advance and inserting hydrogen into the open spaces. This makes an oil less likely to go rancid because you've pre-oxidized it, as it were. You've turned an unsaturated fat (one with at least 1 double bond) into a saturated fat (one with no double bonds). This is why it's a thick liquid to semi-solid ingredient. Saturated fats lie in a straight line (more about this below), so they pack together more easily. When triglyceride molecules are packed together well, they become a solid oil with a higher melting point.
Is this ingredient safe? Cosmetic Ingredient Review did Safety Assessment of PEGylated Oils as Used in Cosmetics, and came to the conclusion that PEG-40 hydrogenated castor oil can be used at up to 100%, meaning you could use it neat on your skin.
This is a seriously interesting document and I encourge you to take a look at it if you're interested in how these conclusions are reached. They go into great detail - including transcipts of conversations - into how they plan these reivews and how they execute them. Quite interesting.
solubilizer, it's used like polysorbate 20 or 80, Cromollient SCE, Caprol Micro Express, caprylyl/capryl glucoside, and other solubilizers to incorporate small amounts of oils into water based products like body washes, toners, and so on. It's supposed to help create clearer solutions in surfactants, clearer than polysorbate 20 or 80, which can produce clear solutions with the right fragrance oil. I've seen suggestions of 2% PEG-40 hydrogenated castor oil to 0.4% fragrance oil as a starting point.
With polysorbate 20 or 80, I've seen it suggested that we mix the fragrance oil and polysorbate together, then add it to the product. I've seen PEG-40 hydrogenated castor oil added this way, and I've seen it added into a product with the fragrance oil coming later. It can be added to the heated phase, and probably should because it's a bit viscous to be used cold. Having said this, the cool down phase isn't cold as it's around 45˚C, which means it will melt in that phase, too.
As a foam booster, it can be used at up to 10% in a surfacant based product.
As an emulsifier, it needs to be used with a low HLB emulsifier like glycol distearate (HLB value 1) or glyceryl stearate (3.8) to create an all in one system. It isn't an emulsifier on its own.
Summary of PEG-40 hydrogenated castor oil:
It's an emulsifier, surfactant, solubilizer, and foam booster.
Miscible in water and oils.
Use in the heated oil or cool down phase at 1% to 10%, although it's safe to 100%.
Non-ionic, and compatible with non-ionic, anionic, and cationic ingredients and products.
Derived from castor oil.
HLB is 15
pH (3% in water) is 5.5 to 7 (acidic to neutral)
Making fragrance sprays with caprylyl/capryl glucoside (including other solubilizers)
Join me tomorrow for more fun with PEG-40 hydrogenated castor oil as we try a few fragrance oils with it!