Friday, February 25, 2011
An aside: Let's talk about drier feeling oils...
Allow me to recap a post from last year with a bit more detail...
An astringent is actually defined as "chemical that tends to shrink or constrict body tissues, usually locally after topical medicinal application." By definition an astringent isn't necessarily a drying thing, but we do perceive moisturizing ingredients with astringent qualities as drying. These more astringent oils and butters still moisturize well, but they will give you the perception of being drier than regular oils.
Let's take something like mango butter, considered a dry or astringent butter. The tannins in the butter may make it feel astringent, and it may "shrink or constrict" your skin, but the fatty acids and phytosterols are still offering amazing moisturizing qualities, so you are still getting a nicely moisturizing creation!
If you take a look at non-oil based astringents, like alcohol or witch hazel, these can be drying because they don't contain all the lovely emollients we find in our esters, oils, and butters. (This is one of the reasons that cetyl alcohol isn't drying - it might be an alcohol by chemical definition, but it's a fatty alcohol, so it has that fatty or emollient part on it, which overcomes the drying possibilities of the alcohol part!) Witch hazel is less astringent and drying than alcohol, and can actually offer some moisturizing features for oily skin (click on the post to learn more).
Let's say you want to use an astringent butter or oil on dry hair or skin, will it still moisturize? Of course it will, because it contains all those lovely fatty acids. If you use an ester on dry hair or skin, will it still moisturize? Yep, because it's still an emollient. The chemistry of our drier feeling or astringent oils and butters means it feels drier but it will still behave as an emollient moisturizer that will do all the great things the non-astringent feeling butters, oils, and esters!