Monday, April 20, 2009

Better crafting through chemistry: Emollients

Isn't this a beautiful molecule? It's castor oil! This is a triglyceride - three fatty acids connected to a backbone of glycerol (glycerin) - the 3 oxygen atoms at the top. The zig zaggy lines indicate a carbon molecule and the OH are the hydroxyl groups we saw in yesterday's post. Finally, the double lines in the middle of the zig zaggy bit are double bonds - this is what makes this unsaturated. Those double bonds can be broken and we get rancidity!

What the heck are emollients? They are the ingredients we add to our creations to offer soothing and moisturizing to our skin. Emolliency is a vital part of our skin's needs: Adding emollient ingredients can help us immediately relieve some of the discomfort of dry skin and helps plasticize the skin. So we want emollient ingredients in everything we make!

There are many emollient ingredients you can choose - oils & butters, proteins, hydrosols - so let's take a look at a few of those.

Vegetable triglycerides, or as we know them oils and butters, are the main ingredients used in lotions to soothe and moisturize our skin. There are some down sides to using vegetable oils. They are unsaturated, which means they are prone to rancidity, and they can impart a greasy feel to our creations. Most vegetable oil molecules are quite large, which makes them harder to emulsify than something like mineral oil. But they offer so many benefits in the form of the unsaponifiables - sterols, vitamins, minerals, and so on that will not saponify (yield fatty soap in the presence of caustic ingredients like sodium hydroxide) - that we want them in our lotions! Different oils offer different benefits - longer shelf life, more minerals, some lovely vitamins - so you can choose your oils and butters to suit your needs.

Please visit these posts for more detailed information...
Anti-oxidants (to retard rancidity)

Hydrolyzed proteins like oat, wheat, corn, silk, and soy proteins are film formers and emollients. They contain oligosaccharides (long chains of glucose) and amino acids. They are water soluble, thus not appropriate for oil only creations.

They work on your skin by penetrating the outer layers of the stratum corneum and function as moisturizers. They also work as irritant mitigators in anionic surfactant mixtures, so they are a great addition to any body or facial cleansers. In hair care products, they can penetrate the cuticle into the cortex and help reduce cortex damage.

They also help you retain moisture in your skin or hair, meaning they do have some humectant qualities.

I'm planning to go into more detail about hydrolyzed proteins in the near future, so look for it!

Cationic quaternary compounds are great emollients to add to your creations. They are substantive - these ingredients are positively charged, so they are attracted to the negative charges of your skin and hair, where they will be deposited and remain on your skin or hair. The fats in this molecule are the moisturizing ingredients, and offer emolliency (moisturizing and soothing) of your skin and hair.

Cationic polymers (like honeyquat, condition-eze 7 or polyquat 7) are also emollients to add to your creations. Again, they are substantive like the quaternary compounds, but they do not contain the fats the compounds contain so they as moisturizing something like Incroquat BTMS. The substantivity they offer makes a huge difference for cleansers or toners, because you are adding a component of moisturizing to an otherwise non-moisturizing product.

So there you have a few ideas of why we add these ingredients to our products. So let's move on to the last piece of the skin pleasing puzzle - occlusion.

1 comment:

France said...

Hi Susan!
You're blowing my mind with all this chemistry but I look forward to having a little quite moment so I can read and understand! It's fascinating!