Tuesday, April 29, 2014

A more detailed look at decyl glucoside: Some basics about it and the pH

Decyl glucoside is a very mild non-ionic cleanser that works well as both a primary or secondary surfactant as it is a good foamer. It has an alkaline pH - 7 to 11.5 - so you'll have to bring your pH down with citric acid or another acidic ingredient to ensure it reaches the right pH for skin and hair. It contains about 48% to 52% active ingredients in the surfactant, and the suggested use is 4% to 40%. This is a great ingredient for a conditioning shampoo or body wash as it improves the cationic conditioning in your products, as well as offer foam stabilization.

Part of the appeal of decyl glucoside is how it is manufactured, and its Ecocert status. "Decyl glucoside is produced by the reaction of glucose from corn starch with the fatty alcohol decanol which is derived from coconut." (Wikipedia) So you can say it is derived from sugar and coconut.

It is not thickened by salt, so you'll have to find another way to do it. You could use guar gum, xanthan gum, or carbomer (gelling agent). You can use Crothix, but it seems that Ritathix DOE is designed to work better with it.

Here's the problem with decyl glucoside - the pH level. It's high, so make sure you know the pH of the specific decyl glucoside you're buying. (Ask your supplier for this information.)

As a quick aside - why do we care about the pH? Because our hair and skin want things that are acidic or have a pH lower than 6. Decyl glucoside has an alkaline pH or one that is above 8. This can make our skin feel dry or scaly and can make the cuticle of our hair stick up, leading to damage. 

Related posts:
Chemistry of our skin: pH of our skin

As much as I'd love to say that you can use pH strips to test the pH, they aren't sensitive enough for this application and you can get false or pointless readings that won't offer enough information. If you are going to be using this surfactant quite a bit, invest in a good pH meter, and learn how to reduce the pH in your products. They tend to cost between $50 to $120, and I recommend you check the supplies necessary for your meter before buying.

I have a Jenco machine and it doesn't require me to replace the electrodes or other things, which is awesome! 

I'm afraid I can't offer any rules about how to adjust the pH because there are too many variables. For instance, if you add 10% decyl glucoside to water, you'll have a lower pH than adding 20% decyl glucoside or 30% decyl glucoside. It will depend upon the other ingredients in the product. If you have some ingredients with a lower pH - say lactic acid - then you'll have a lower pH than a product without those acids. And it will depend upon the initial pH of your product. If you have something that has a pH around 8, it'll be easier to get it to the acidic level you want than if you're starting with 11.5.

More information on pH meters
What pH meter should I get?
Adjusting the pH of our products
More about adjusting the pH of our products

Join me tomorrow as we take a look at using decyl glucoside as a substitution in a few products.


Sandra said...

Thanks Susan for this post, I really appreciate it when you write about hair care, I find this to be the most complicated category of cosmetic chemistry, but you explain it all really well!

Just one more question, I have heard that it's not possible to mix xanthan gum with polyquat 7, honeyquat or BTMS, and I just wonder why. Is it the same with guar gum? I'm thinking this might be why the gum thickening isn't working with my shampoo even though I've lowered the pH.

Rolanda Bell said...

Thank you so much for this post. I was using pH strips and I got one result. I switched to another type of strip and got something totally different. I use this product quite a bit, so I will invest in a pH meter.