Sunday, September 26, 2010
Better crafting through chemistry: Sorbitol
In this post on humectants, Aesthete asks: I was re-reading this post on humectants and was wondering if you've ever formulated with sorbital? It's described as having "excellent plasticizing & thickening effects providing viscosity & texture, stabilizes gels & provides good clarity, effective moisturizing properties, good smoothing & conditioning effects." It almost sounds too good to be true...I really value your opinion and if you have one on this ingredient, I would love to hear it. Thank you.
Sorry, Aesthete, but I've never formulated with sorbitol, but I can share my book learnin'!
Sorbitol is a water soluble humectant originally derived from berries and fruit that can be used at 0.5% to 15% in our creations. We generally find it in a 70% aqueous solution that is easily dissolved in water but not so much in alcohol. It's a sweetener that can be used in toothpastes and mouthwashes as well as diabetic foods, but it has a laxative effect if you ingest too much (more than 20 grams per day!).
Like other humectants, it's a thickener and a desiccant, meaning it absorbs water away from other ingredients (like those little DO NOT EAT packages we find in computer parts or shoes). It will help thicken your lotions and surfactant based products, increase clarity in bubble baths and body washes, and reduce the freezing point of our products.
You can combine it with glycerin to reduce the feeling of tackiness from that humectant, although it has a little tackiness of its own.
On the scale of hygroscopic abilities, it rates below our other commonly used humectants (the scale looks like this - sodium PCA > sodium lactate > glycerin > sorbitol).
So does it do all those wonderful things you mention? Yep. It's a moisturizing and conditioning ingredient - it draws water to our skin to increase moisturization and make it feel nicer. The smoothing part means it will make your skin feel smoother, and it will do that. It is a plasticizer in that it increases the fluidity of our products. It helps increase clarity of our surfactant based products and decreases the freezing point.
But these features aren't unique to sorbitol - glycerin and propylene glycol will do these things as well. In fact, glycerin is highly recommended for dry or wrinkled skin because of the moisturization and conditioning properties. So why use it?
It's a good substitute for glycerin as it is less tacky than that humectant, and it's a good substitute for propylene glycol for those who don't wish to use it. It won't make you sun sensitive like sodium PCA or sodium lactate. You can use it as a humectant in deodorants at up to 5%, but don't use it as the main polyol in that product as it won't work well.
Hope this answers your question!