Let's take a look at a few combinations of oils, butters, or exotic oils to see what they bring to the mix. (I chose some of these at random to see how they would combine).
These two oils combined have very little linoleic acid, but the punicic acid in pomegranate oil is an anti-inflammatory ingredient that can increase skin's elasticity and help repair sun and weather damaged skin. The palmitic acid from the shea butter offers occlusion. The stearic acid offers improved moisture retention, increase in flexibility of the skin, and skin damage repair. The oleic acid is absorbed by our skin for increased moisturizing and cell regenerating features, as well as skin softening.
They have a nice amount of anti-oxidants in the form of the polyphenols and tocopherols, and offer a lot of wound and burn healing. The shea butter offers some occlusion and allantoin. Pomegranate oil is considered dry and shea butter is considered greasy, so they might balance each other out.
This would be a very nice combination for someone with very dry or chapped skin, inflamed or reddened skin. It would serve to occlude the skin from further damage from the elements, and repair damage to the skin and increase moisture retention. The Vitamin E is moisturizing and softening, as are the various fatty acids. And if there is damage to the skin through burns or scratches, there are a lot of wound healing ingredients.
There isn't much linoleic acid in this combination, so we don't get all the skin barrier repair functions bonuses, but the other features make up for this.
Mango butter and pumpkin seed oil. Combined shelf life 6 months (shortest life span is pumpkin with 6 months)
With this combination, we're getting a bit of everything. All the fatty acids are represented in medium to high quantities, we have some nice anti-oxidants in the tocopherols and polyphenols, as well as some lovely phytosterols for the anti-inflammatory properties. This would be a good combination for pretty much everyone as it is well balanced - the mango butter is astringent, the pumpkin seed is greasier.
So what do we see when we combine these oils? A balance of all the various fatty acids, a lot of Vitamin E, very high phytosterol amounts, and great anti-oxidants. We also get some UV protection and after sun exposure repair, as well as a humectant. Squalene is a great skin penetrator and softener. Sunflower is considered light and greasy, while olive oil is considered heavy and greasy. This combination is going to feel medium weight on your skin but very greasy.
Here's the big question...Why not use something like rice bran oil that already has a nice balance of fatty acids, some Vitamin E (400 ppm), nice phytosterol levels, squalene. and ferulic acid as a wonderful anti-oxidant? It has squalene for moisturizing and softening, and t's a greasy feeling, medium weight oil.
The answer: Why not? If you want to use one or two oils exclusively, enjoy it!
When it comes down to it - most oils are oils. They soften and moisturize and trap the water near your skin by forming a thin film. I know I've said it before, but I believe in knowing your ingredients. If you love rice bran oil and want to use it in everything, then use it in everything (I know I do!) If you want to create a moisturizing, softening lotion that feels good on your skin, then choose the oils that make your skin feel softened and moisturized. I've been using the same combination of oils in my hand lotion for almost four years - rice bran oil, soybean oil, and fractionated coconut oil - and I chose them because they were inexpensive and available, and offered my product a long shelf life. I like the mixture of the very light, light, and medium weight oils. After all I've learned about oils and butters, I'm not changing this recipe because I like how it feels!
If you find a recipe you like, but don't have the oils, knowing your ingredients lets you figure out what each brings to the party and how to substitute them. If I find a recipe with rice bran oil and sunflower oil, I know that I want a medium weight oil with oleic and linoleic acids and a light weight oil with high linoleic acids. I could use soy bean in the place of the sunflower oil and sesame oil in place of the rice bran oil.
One disclaimer - most oils have an HLB value of 7 to 8, or so. Using an oil that has a different HLB - like fractionated coconut oil or castor oil - could mess up the emulsification system if you're using the HLB system to create your emulsifier. It's fine with an emulsifying system like Polawax, emulsifying wax, BTMS, and so on, but if you've come up with your own system and switch out the oils, please re-calculate the HLB again to ensure you won't get separation!
Having said all that, over the next few days, let me take you on a journey of how my brain works when I'm formulating with various oils. (Abandon hope, ye who enter the mind of Swift! It's a bit like going to the carnival - on the one hand, you like the cotton candy; on the other hand, the bearded lady creeps you out!)
Please share your thoughts on your favourite oil combinations in the comments!