Wednesday, September 6, 2017

Weekday Wonderings: Can we make a shampoo bar without cocamidopropyl betaine?

In this post on shampoo bars, Bella asked: Is it ok to make a syndet shampoo bar without cocamidopropyl betaine? Everyone makes it seem like an impossibility, but there is a company that makes them and they are sellilng very well and I don't see that ingredient in their product. The company is Ethique, here is the ingredients: Sodium cocoyl isethionate, sodium coco-sulfate, decyl glucoside, stearic acid, Cocos nucifera (coconut) butter, Theobroma cacao (cocoa) butter, vegetable glycerine, coco caprylate, cetearyl alcohol, coconut milk powder, Mentha piperita (peppermint oil), copper chlorophyll, lactic acid. I read that cocamidopropyl betaine some people are very sensitive to, so I was hoping to do without it. It is also really hard to find in small amounts to buy. Is using decyl glucoside enough to make the bar less irritating?

Yes, we can completely make a shampoo bar without cocamidopropyl betaine, but there are so many reasons to use it. Here are two...

1. It helps melt sodium cocoyl isethionate well. SCI can be a bit of a pain to melt, especially if you're dealing with noodles or flakes, and cocamidopropyl betaine gets that process going faster.

2. Cocamidpropyl betaine makes surfactant blends milder, which means less irritation.

Decyl glucoside isn't the mild surfactant everyone seems to think it is. It's nice and all, but it can have a super high pH - we're talking as high as 11, which is terrible for hair - and very few people think about reducing that to an acidic pH. You'll notice in the ingredient list you mention, there's some lactic acid there, perhaps to reduce the pH. In fact, the alkyl glucosides, of which decyl glucoside is one, was declared the allergen of this year because of all the contact dermatitis they think it's causing. If you plan to use it, please make sure you reduce the pH to a more hair friendly level of 4.5 to 6-ish.

If you don't want to or can't use cocamidopropyl betaine, consider one of the other amphoteric secondary surfactants like disodium cocoamphodiacetate, sodium cocoamphoacetate, cocamidopropyl hydroxysultaine, or sodium lauroamphoacetate. All of them will increase the mildness of the product.

I've been working with all kinds of surfactants over the last 18 months, and I'm so excited to be able to share more about them in the next month or so! 


Lehni R. Kersher said...

Oh no I just bought decyl glucoside to make a dupe of Arbonne's calm facial cleanser. So far the cleanser has been ok (my surfactants were decyl glucoside 7%, Sodium Lauroyl Sarcosinate 3%, coco betaine 10%). Adjusted to ph approx 5.5-6.0 (used strips as my new ph pen just wouldn't calibrate). No issues so far but I will keep that in mind in case we get symptoms.

Lehni R. Kersher said...

oops I forgot I added around 50% more water on the fly as the viscosity was wrong so the eventual surfactant proportion was more like 13% not 20% in total so dg approx. 4.7%, slsarc 2%, coco betaine 6.7% (I adjusted the preservative up by another 50% too but didn't bother to adjust the humectants or other ingredients).