Thickeners: Xanthan gum

I've written about xanthan gum before, but I thought I'd go a little more in depth in this post!

Xanthan gum is an anionic polymer derived from the bacterium Xanthomonas campestris, which can be found on cruciferous veggies like cabbage, cauliflower, and broccoli (all of my least favourites!). In the manufacturing of this ingredient, they actually use the bacteria in a fermentation process. It's permitted in food and cosmetic products and the typical usage is about 0.1% to 0.3%.


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 - which means surfactants like decyl glucoside that don't contain a ton of salts with thicken nicely with it - but low concentrations of anionic and amphoteric surfactants (just about every other surfactant). 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. Salts can slow down the hydration of xanthan gum, but don't have much of an effect on it once it's hydrated, so don't worry about adding things like aloe vera that contain a ton of electrolytes.

You can use xanthan gum in your lotions in the oil phase of the lotions (which doesn't make sense to me as it is a water soluble ingredient, but that's what the data sheet suggests) 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)! So don't go below 0.1%. I've been experimenting with xanthan gum and Sucragel in lotions, and I've found 1.5% to 2% thickens a Sucragel lotion very nicely (and they're usually quite thin, no matter how much cetyl alcohol or butters you include in the mix).

Xanthan gum is pseudoplastic, so when it is subjected to stress it will thin out but will thicken up again when the stress is removed. And although it won't dissolve in alcohol, it is compatible with up to 60% alcohol, so it is an ideal thickener for making hand sanitizers. And like the other gelling agents we've seen so far, it will help decrease the freezing point of your products so they're easier to ship or store.

As a note, xanthan gum works really well in concert with other gums or thickeners. It works best with guar gum (80% guar gum to 20% xanthan gum) and with locust bean gum (50-50).

Join me tomorrow as I start experimenting in the workshop with these various thickeners in various products!

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Thickeners: Hydroxypropyl methyl cellulose (HPMC)

Hydroxypropyl methyl cellulose (also known as hypromellose or HPMC as I'll be typing from now on!) is a non-ionic, water soluble polymer derived from cellulose. It comes as a white or off-white odourless powder that we use to thicken our products. Because it's non-ionic, it has many uses like shampoos, lotions, shaving gels, and pretty much any product you want to thicken.

The cellulose derivatives, like HPMC and hydroxyethyl cellulose (HEC) are created through a reaction of cellulose with ethylene or propylene oxides or both to create these products.

HPMC is kinda weird because it's very soluble in cold water and almost insoluble in hot water (and remember, things tend to be more soluble when you add heat, which is yet another reason to heat and hold our products!). With most of our thickeners, we add them to the water first and allow them to hydrate before heating; with HPMC, it's best to add it to cold water and allow it to hydrate but don't add it to the heated water phase of our products. We'd then add that to the cool down phase of our products. I know, it's weird! This is because it doesn't gel in heat, it gels in cold, so it basically congeals to create a semi-flexible mass. The more HPMC you add, the lower critical temperature needed to achieve gelling.

Yes, I know that last paragraph is very strange and I'm trying to wrap my head around it. I've searched through tons of manufacturers' recipes and although I've found a few where the HPMC is used in the water phase and heated, almost all of them suggest adding it at the end or making the entire surfactant based product cold. 

If you want it to just be part of your lotion to offer a silky feeling, then add it to the heated stage at 0.1% to 0.3% and use it as part of your heated water phase. If you want to use it as a gelling agent for something like a shampoo or even a shower jelly (this is why this series started - I hate carageenan and need something else, and HPMC sounds like the right ingredient), then you can sprinkle it into cold distilled water and add it at the end of the process with the cool down ingredients. (Make sure it is distilled water because we don't want beasties or other contaminants in our products!) Use it at 0.2% to 0.5% in surfactant based products. Or add it to your conditioners at the same amount in the same way (only don't reserve all the water for the conditioner - take out about 10% or so and use that at the end of the process). The general suggested usage rates for HPMC is 0.3% to 1%, with the up to 1% being for proper gels like shaving gels.

HPMC is a great thickener for surfactant based products like shampoo or body wash because it doesn't need salt to thicken, so it will thicken things like decyl glucoside, sulfosuccinates, and SLeS, all of which are difficult to thicken with salt. It won't interfere with our surfactants' cloud point or titer point, which means you can achieve a clearer product. Like the other gelling ingredients we've seen so far this week, it offers freeze-thaw stability, meaning it will work like anti-freeze for our products.

Finally, because HPMC is pseudoplastic (which means it exhibits shear thinning) we can make our products quite thick and still have them squeeze out of the bottle.

Join me tomorrow for fun with xanthan gum (reprised).

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Thickeners: Guar gum

Don't confuse guar gum with cationic guar gum - regular guar gum is non-ionic and does not offer any substantivity to your hair, and it's a fine white powder, not a yellowy powder. It will, however, behave as a good thickener for our products. It's water soluble and non-ionic, which means you can add it to more products than you could an anionic thickener like xanthan gum.

85% of guar gum is a water soluble polysaccharide called guaran. This is what gives it its thickening abilities. (That's the interesting molecule to the left!)

Guar gum is ideally used in products with a pH of 5 to 7, but it can handle higher and lower levels without degradation. We need to hydrate it before using it in our products, so it's suggested that you sprinkle the guar gum over your room temperature water phase, stick blend or mix well, then leave to sit for about 15 minutes or so or until it is well hydrated (you'll be able to tell because it creates a gel). Then you can add your other water phase ingredients like aloe vera, hydrosols, proteins, and so on and heat and hold as usual. The usage suggested ranges between 0.3% to 5%, so you'll have to do some playing to figure out the best usage for your product.

Guar gum offers more than thickening. It can behave as a light emulsifier as it prevents oil droplets from coalescing. It can behave as a stabilizer as it keeps solid particles from settling in a bottle. And it can behave as an anti-freeze by retarding ice crystal growth in our products (which is very useful when you're shipping things across the country and don't know where it might end up sitting for a while!).

Because guar gum is non-ionic, there are really no limits on where you can use it. You can use it in lotions, surfactant products, conditioners, and pretty much any product where you might want a little thickening. It is water soluble, so it's not suitable for use in anhydrous products.

Join me tomorrow for fun with hydroxypropyl methylcellulose!

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A little chemistry on thickening...

Here's a little chemistry to start your day! Let's take a look at colloids, hydrocolloids, and shear thinning.

What is a colloid? A colloid is "a substance microscopically dispersed evenly through another substance." It can be a gas, solid or liquid. It consists of two phases - the dispersed or internal phase and the continuous or dispersed medium. Does this sound familiar? It should because lotions are considered colloids (liquid-liquid colloids)! The dispersed medium or continuous phase is the water phase and the dispersed or internal phase is the oil phase. So you've been making colloids and didn't know it!

What is a hydrocolloid? A hydrocolloid it's a colloid system where the colloid particles are dispersed in water, and it can be a gel or a liquid. If it's a liquid, it's called a sol - a colloidal suspension of solid particles in a continuous liquid medium, like blood or toner (I probably shouldn't have put those two things together - what an association!). The thickeners we'll be discussing like guar gum, xanthan gum, cationic guar gum, and so on create hydrocolloids.

What is shear thinning? We see this phrase thrown around quite a lot in lotion making, but it's applicable to gels and just about everything else we make. Shear thinning refers to a situation where the viscosity of something decreases with the rate of shear stress. It can refer to when we're mixing our lotions - when we're stick blending or mixing it, it will seem thinner than when the lotion is at rest - or to when we're using our products - squeezing a bottle will reduce the viscosity of the product. When we stop applying stress - stop squeezing, mixing, or pumping - the product returns to its original viscosity. (Materials that exhibit shear thinning are called pseudoplastic materials.)

What is thixotropy? It is a property of certain gels or viscous fluids: They become more fluid when we apply stress like shaking or squeezing a bottle. It takes a finite time to attain its original viscosity when introduced to a change in shear stress.

Thixotropic materials see a reduction in viscosity over time at a constant shear rate.
Pseudoplastic materials see a reduction in viscosity at an increased shear rate. Meaning, the viscosity decreases as we apply more stress. If we keep the stress the same, the viscosity will remain the same. With a thixotropic material, the viscosity will reduce over time if we keep the stress the same. Guar gum is an example of a thixotropic material when used at 1% (but not at 0.3%).

So let's get back to our regularly scheduled programming and take a look at guar gum!

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Thickeners: Cationic guar gum

I finally got around to buying some cationic guar or guar hydroxypropyltrimonium chloride (sometimes listed as GuarSilk) a few weeks ago from Creations from Eden (also available at the Herbarie) and I thought I'd try it out in a few surfactant based products to see how it compares to my other cationic polymers (like polyquat 7, polyquat 10, polyquat 44, and honeyquat). So what is cationic guar gum?

Guar gum is "a galactomannose polysaccharide derived from the endosperm of Cyamopsis tetragonolobos seeds" (aka guar beans). The guar gum is then depolymerized and its molecular weight is modified to increase solubility and thickening properties. Cationic guar derivatives are created by reacting hydroxypropyl with epoxypropyltrimethyl ammonium chloride to create a positive charge. (Polyquat 10 and 24 are derived from cellulose - the numbers on the polyquats indicate what the starting ingredient was, not how many molecules or other thingies are on it.)

So cationic guar gum is guar gum that has been modified to have a positive charge, which means it will be substantive to our hair and skin, so we use it as a conditioning agent in our products.

So how do we use it? Cationic guar gum comes as a light yellow powder, and we use it at 0.2% to 1% in our products. It's soluble in water, dispersible in glycerin and glycols, and insoluble in oils. It works best in a solution with a pH of 7 or lower (its actual pH is around 9) because that's when it'll have a positive charge (it's not substantive without the positive charge, so this is very important) and when it thickens best. It can create gels, although they might be hazy, and they work well with our surfactants, so we can make conditioning shampoos, body washes, and any other cleansing product where you want a little thickening and conditioning.

There's one down side to using cationic guar gum - it's not as easily removed from our hair by our surfactants as some of our other cationic polymers, which means it can lead to build up on our hair.

The suggestions I've seen for using it are as follows - add to room temperature distilled water and mix well, stirring occasionally for about 15 minutes (although it could take as long as 30 minutes). When the cationic guar gum is hydrated, add to the heated water phase of your product and stir well.

Cationic guar gum is film forming, imparts a smooth and silky feel to skin, acts as an anti-irritant and mildness increaser in surfactant systems, and can increase your foam feel and quality. And it's a conditioning agent that is substantive, but I've already mentioned that quite a few times!

Please note: Normal guar gum does work as a thickener, but it is not positively charged, so it won't act as a conditioning agent and isn't substantive. You need to use the cationic guar gum to call something a conditioner. 

Join me tomorrow for a little more on thickeners - guar gum!

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Experiments in the workshop: Min-maxed toner becomes a facial gel

The weather outside here is frightful, and I need something more than my toner to protect my skin right now. An oil filled moisturizer isn't an option at the moment as I'm having some fun new break outs on my face, so I thought I'd try making my min-maxed toner into a gel using Amaze XT. (Sorry this picture isn't in a bottle, but it's about -3˚C or 26.6 F in my workshop right now and that's where the bottles and funnels are located. I like the cold, but not that cold!)

I modified the recipe to remove the witch hazel as I'm not a fan of it in my leave on facial products, and I left out the salicylic acid or white willow bark because I'm out of both. (I would have happily included it if I had it!) You'll notice this recipe is in grams - it totals 90 grams because apparently math isn't my strong suit this week! Because the thickening is essential to the recipe, I don't want to modify it to equal 100%, so if you want to double or triple the batch, use the recipe as listed below.

TONER BECOMES GEL MOISTURIZER
HEATED WATER PHASE
15 grams water
20 grams lavender hydrosol
20 grams chamomile hydrosol
10 grams aloe vera
2 grams sodium lactate
2 grams hydrolyzed protein
0.5 grams allantoin
1.5 grams Amaze XT

COOL DOWN PHASE
3 grams honeyquat
5 grams Multifruit BSC
2 grams panthenol
5 grams liquid green tea extract
3 grams Caprol Micro Express or another water soluble oil or ester
0.4 grams liquid Germall Plus

Weigh all the heated phase into a heatproof container and heat until it reaches 60˚C. Hold for about 20 minutes, then add the Amaze XT and remove from the heat. Mix really well until incorporated. Wait until the mixture reaches 45 ˚C to 50˚C, then add the cool down phase. Again, mix really well until incorporated. Yay! You have a gelled toner!

Amaze XT is a form of xanthan gum and you could use that in this recipe, but it will feel a bit stickier. (Click here for some information on gelling ingredients.) You can use carbomer or xanthan gum or your favourite gelling agent for a product of this nature to make the gel.

You can leave out all the hydrosols if you want and use water in their place, and you can include any extracts you like. The key is that you can't use paraben based preservatives with Amaze XT, so make sure you've chosen your preservative wisely!

I really like this product! I've used it two days in a row and it doesn't feel sticky on my skin, but I feel moisturized. You don't want to put a thick layer on your face as it will come off when you rub it, and a thin layer is all you need. Yay! A gelled oil free moisturizer for me in this very cold weather time!

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