Sunday, April 25, 2010

Surfactants: Building viscosity - creating gels

This is the last in the very long series of posts on surfactants before we get to some super fun formulating! We've covered the idea of increasing the micelle size and increasing the concentration of the surfactants, so let's take a look at creating gels.

There are a few ways to create a gel that will thicken our surfactant mix. We can use polysaccharides, carbomers, or something like Amaze XT.

Polysaccharides like agar, carageenan, guar gum, gum arabic, locust bean gum, pectin, xanthan gum (anionic), carboxymethocellulose and variations on the methocellulose (non-ionic), and modified starches are great options for forming gels. (Since I'm still experimenting with carageenan, I won't comment on it just yet!) Because these are botanical in nature, make sure you preserve these well with the maximum preservative allowable!

Xanthan gum is made from saccharide monomer units d-glucose, d-mannose, and d-glucoronic acid. It dissolves in most acidic solutions (less than pH 7) and shows great stability in presence of most organic acids (like vinegar, lactic acid, AHA, and so on). It also shows good compatibility with many basic compounds, but something that is very alkaline like lye (pH around 12), you might see some precipitation of xanthan gum and salts. It is also unusually good with salts, but solubility is an issue. There is an incompatibility of xanthan gum and metal ions in solution with high pH, so addition of EDTA is a good idea if you're using some high pH ingredients like lye (although I can't see a good reason to make a really high pH product...)

Xanthan gum shows good compatibility with non-ionic surfactants in high concentrations, but low concentrations of anionic and amphoteric surfactants. It's not compatible with quaternary compounds, or you want to avoid using something like BTMS, honeyquat or polyquat 7, or Tinosan as your preservative.

You can use xanthan gum in your lotions in the oil phase of the lotions and in your surfactant mixes in the heated water and surfactant phase to create a rich creamy lather. But remember, if you're making a shampoo, leave the honeyquat and polyquat 7 out!

Make sure you're using 0.1% to 0.3% because at lower levels in a lotion, it can actually enhance flocculation and creaming (otherwise known as an epic lotion fail)! EEEK!

You can use a polymer like Carbomer or ETD 2020 to create a lovely gel that will thicken our mixture and suspend things like jojoba beads or pumice for a scrub. (Click on the link as I've already covered this...)

You can use a product like Amaze XT (INCI: Dehydroxanthan gum), which is a modified form of xanthan gum. Use it at 1% to 2% to create a gel without neutralization (unlike the carbomers) in the heated water part of the product. It is soluble in water and alcohol for creating gels. You can't use paraben based preservatives with Amaze XT based gels, which means Phenonip and Germaben II are right out. You can use liquid Germall Plus, Optiphen ND, and Tinosan SDC without problems.

Amaze XT is anionic, and it is compatible with silicones, propylene glycol, hydrolyzed proteins, EDTA, sodium phosphate, and low levels of Flexan II, a polymer used in hair styling products (3:1 ratio of Amaze to Flexan II). In emulsions, you can use carbopol, Structure XL starch, xanthan gum, and hydroxyethyl cellulose as well.

The ideal pH for products containing Amaze XT is between 4.5 and 6, which is right where we want our skin care products. Below 4.5, you'll see a decrease in clarity, so you can add a little salt at 0.1% to make it a little more viscous.

I have been playing with Amaze XT - these recipes from Voyageur - and I just love it. It's great for a suspending type of cleanser and really nice in a very light lotion. The moisturizing sorbet I've linked to would be fabulous for a light lotion for the summer time for oily skinned people (low oils, high humectants).

All right! Let's get making some surfactant based creations for our various skin types!


Tara said...

I find xanthan gum is pretty good to work with, although the formulations aren't clear.
HEC, which is supposed to produce "crystal clear" products, is the WORST thing I have ever used! I repeatedly get crappy results, usually ending in separation of gelly HEC and watery surfactants

Jen said...

Susan, is Xanthan gum incompatible with all quats? The reason I ask is I have been playing around with making a liquid shampoo that happened to contain SCI, SLSa, SCB, and DLSS for my surf blend and polyquat 44, a little BTMS (other ingredients, as well). It has a very smooth and creamy consistency and performs awesomely as a hair shampoo/body wash. What sort of reaction would I have from the guar gum? Flocculation, separation (of which I haven't had any) or is it more a case of altering the effectiveness of the other ingredients?


Eden said...

Hi Susan!

Thanks for a great blog and for your awesome hair care products book that I downloaded from lotioncrafter a while back.

I am creating a clarifying shampoo,(with about 5% oils including fragrance) and in an effort to avoid polysorbate, I have the idea to use gum arabic as both a thickener and emulsifier. 2 questions arise for me regarding this:

1. Will this be too sticky/ film forming for a shampoo?

2. I am failing to find any pointers as to how much percentage-wise to use to accomplish both emulsification and thickening.

Any insights or knowledge you can share would be greatly appreciated.



Frckls said...

Hi Susan!

First, I have to say, your blog is amazing! I like how science is broken down to commoners like me.

I love okra gel for my 2c curly hair. My first try was plain okra with xantham gum and it was amazing. I want to amp up the game and was thinking to add honeyquat and/or BTMS to make it as a curl cream with hold (with some other hold providing ingredients, of course). Is can xanthan gum really that incompatible with cationic ingredients? Or is there a threshold amount for it to do that?

Thank you!

Susan Barclay-Nichols said...

Hi N. You can try making your gel with cationic ingredients. Keep really great notes and watch it over time to see how it reacts to the cationics. That's really the only way to see if this works or not!

Maggie N. said...

Hi Susan
About using the xanthan gum in the oil phase dispite it being water soluble, it is similar to making a roux with flour and butter instead of adding flour directly into your sauce. The xanthan gum soak up the water on contact, creating little lumps that are hard to mix out. So dispersing the xanthan gum through the oil phase first helps to evenly distribute it before it hits water and gel up. Atleast that's how I understand it.

Terry Norfolk said...

Hi Susan, love this tutorial blog of yours. Its an endless wealth of flawless info. Thanks for all of it. In response to Maggie N's comment re: Xanthan Gum. yep what a nasty little horror show that one is. I tried "dissolving" it in glycerin then introducing it into the water. Makes a big difference for sure. I haven't tried predispersing into oil though, and thank you for the suggestion as I am going to use that method right now.
Thanks all, for your useful comments, they are all very useful as are those of The Goddess of Chemistry herself, Susan-Swift

Sven Abrahamse said...

hi, i know this is a really old post but i am trying to do a body wash and would like not to use xanthan gum. For some of my shampoo's i use PEG 150 - distearte or even a product from BASF called Arlypon TT. What do you think? Best Sven