Saturday, August 21, 2010

Point of interest: Aloe vera and the viscosity of foamy surfactant products

I've always wondered why the foamy surfactant based products we've made in our craft groups - bubble bath, body wash, shampoo, and facial cleansers - weren't as thick as those I made at home. I thought it was thanks to my use of volume measurements instead of weighted measurements - yeah, I know, I tell you not to do this, but I did weigh out each of the ingredients to figure out the volume measurement - but I was wrong!

I was leaving out the aloe vera, which is vital to the thickening of our products. I didn't really think about it much; it's a matter of cost when it comes to making bubble bath or body wash with 25 youth! It really is cheaper to use water than aloe vera, and in a bubble bath, does it matter that much? Apparently, yes!

Aloe vera contains electrolytes, like salts, and those help thicken our surfactant mixes. And we know from the way salt interacts with surfactants through the salt curve, the more electrolytes in a mix, the more thickening we'll see. So leaving out the aloe vera means we have fewer electrolytes, which means less thickening.

So if you're making any of the recipes for body wash, bubble bath, shampoo, and so on from this blog and leaving out the aloe vera - which I generally use at 10% - your products will be less viscous than those that include it. This is especially obvious in the daily shampoo recipe, which contains a really low level of surfactants. If you include the aloe vera, 2% Crothix (possibly 3%) will thicken it nicely. If you don't, you'll have to use up to 5% to get the thickening you expect from a shampoo.

So what do you do if you can't use aloe vera due to sensitivities, allergies, or just a desire to avoid humectants for frizzy hair?

You can thicken your mixtures with Crothix, PEG-150 distearate, glycol distearate, or other thickeners suitable for surfactant mixtures at a higher level. This might depress your foam, but it will increase the mildness of the product.

You can add more surfactants to the mix to increase the concentration, which kinda defeats the purpose of something like a daily use shampoo or a mildly cleansing body wash, but can work for a bubble bath.

You can create a gel with something like Amaze XT, a polymer, or xanthan gum.

Or you can add some salt to the mixture. You can do this by adding salt and following the salt curve, or you can add some surfactants that are a little more salty, like cocamidopropyl betaine or SMC Taurate!

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