Thursday, February 3, 2011

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).


Will said...

I actually just posted on today's (Thursday) board something similar to this, but having read this, it's more applicable here.

How does HPMC differ (in use or application) from Sodium Carbomer?


Anonymous said...

Thank you so much for this post. I have been trying to work with HPMC and couldn't get it to blend in to save my life. Now I will go back and give it another shot.

Anonymous said...

I've happened upon your blog in researching HPMC which is used in the Probiotic supplement that I just started taking. It's advertised, and in fact guaranteed to, "Promote Intensive Digestive Relief" to combat constipation. So I'm wondering if the "gel" effect is what is causing the "relief". Any thoughts?

Robin said...

Is Hydroxypropyl Starch Phosphate similar?

Anonymous said...

Can this be used in Dish Gels? Thanks Krissy

Susan Barclay-Nichols said...

Hi Krissy. What's a dish gel?

Addison Chan said...

Hi Susan

I am trying to create a hydrating gel of Magnesium Sulfate (epsom salts) The end product is a gel that contains 5% magnesium sulfate. Should I add the HPMC directly to the 5% MGSO4, or should I hold back some of the water to disolve the HPMC and then combine the two components.


Susan Barclay-Nichols said...

Hi Addison! I'm not sure how to do that as I've never used it on its own as a gelling agent. My suggestion is to do what I suggest in the post - If you want to use it as a gelling agent for something...then you can sprinkle it into cold distilled water and add it at the end of the process with the cool down ingredients.

Hope this helps. Please let me know how this works out as I'm sure others will be more than eager to learn more!

amarisyearby said...

Hi Susan!
I have been playing with hydroxyethylcellulose to make hair gel. I made a 3% gel (I am African-American so I often need products that are a little heavier) with just water and HEC to see how it worked. When I applied it to my hair it dried up into huge flakes. Do you know why this happens? I didn't heat it or anything just added HEC to room temp water and let it hydrate for 30 minutes or so.