Sunday, November 7, 2010

Humectants: Dipropylene glycol & butylene glycol

Dipropylene glycol shares many of the characteristics of propylene glycol, but it has a higher boiling point (232.2˚C vs. 188˚C for propylene glycol) and a higher molecular weight. It's used more as a fragrance fixative than a humectant, although it can behave as a hygroscopic ingredient. It will reduce the freezing point of your products and make your surfactant mixes clearer. It is soluble in water, alcohol, and castor oil. It is a viscous, colourless, slightly sweet tasting (with a bitter aftertaste) liquid.

Dipropylene glycol is used a lot in fragrance oils, and you might see suppliers listing their fragrances as DPG free. It's a great fragrance fixative, although fragrances with DPG can cloud and soften translucent soap bars, so if you're a melt & pour type girl like me, watch out when you're using a clear soap! (It's actually used in shaving bars to make them softer because that's a bonus for that product!) You will notice a difference in non-DPG fragrances - they tend to fade quicker than those with it - so you can extend the life of the scent by adding some DPG or C12-15 alkyl benzoate to your product.

You can use it at up to 50% in the heated water phase of your product, although you'll probably want to use it at 1% to 5% or so. It's a good option for deodorant bars as a gelling agent, and you can use it at up to 10% in that capacity.

Butylene glycol (1,3-butanediol or 2,3-butanediol) is related to the other glycols in that it is also a polyol or polyalcohol (as indicated by those little OHs on the carbon chain). It is soluble in water, acetone, and castor oil. Like the other glycols, it is a viscous, colourless, slightly sweet tasting (with a bitter aftertaste) liquid. It is also a humectant, but it is the most resistant to high humidity than the other glycols, which means it's great for very humid areas. Butylene glycol can be used to retard the loss of fragrances in our products - so if you have a body spray that keeps losing its scent, a little butylene glycol can help retain that lovely fragrance. It's skin irritation is very low - the lowest amongst the glycols - and it is considered safe by pretty much every agency.

You can use butylene glycol at up to 89% in the heated water phase of your product, but you'll probably want to keep it around 1% to 5%. You can use this as the gelling agent in deodorant bars, and you can use it at up to 10% in that capacity.

Join me tomorrow to take a look at mineral oil (insert dramatic chord here!).


DuhBe said...

I'm glad you covered one of my favorite ingredients - butylene glycol. I didn't know about the fragrance boost! I use it in my syndet shampoo bars for 3 reasons (a) solvent to help melt SCI, (b) dispersant for pesky powders like gaur silk, and (c) the humectant property helps the lather last longer.
Luci Lee

Tara said...

Could you use dipropylene glycol in place of propylene glycol for the purpose of a solvent in a toner (to help dissolve salicylic acid)? I can find dipropylene locally, but not propylene...

Raza Naseem said...


Do you have any fragrance lasting solution for body sprays, air fresheners etc?

Pls help me.



Tyler said...

What is the HLB value of Butylene Glycol?

Susan Barclay-Nichols said...

Hi Tyler. Butylene glycol doesn't have an HLB value. You can read more in today's Weekend Wonderings.

Tyler said...

Thanks for the follow up info.

I see "Hexylene Glycol" mentioned a few times elsewhere this humectant-solvent something we should be considering as well?

Anonymous said...

Hello. If you had to estimate, what are the approximate percentages of Behentrimonium Methosulfate, Cetyl Alcohol, and Butylene Glycol in BTMS-50? Thanks in advance.

Susan Barclay-Nichols said...

Hi Ana. It's called BTMS-50 as it has about 50% behentrimonium methosulfate. As for the other ingredients, I don't know. Take a look at this data sheet on Incroquat BTMS-50 for more information!

HG moisturizer said...

Hi Susan,

This is probably going to sound silly but... I'm having a hard time understanding what it means when they say butylene glycol "is resistant to humidity"

Is this only relevant to hair care products? I know some people get frizz when it's really I'm assuming the hair can absorb moisture from the atmosphere and if it takes in too much >>> poofy frizzy hair?

So in this case butylene glycol might help "resist" the humidity by somehow preventing hair from absorbing moisture from the atmosphere...?

That's the picture I have in my head >_> I'm not sure if it's accurate at all I'm pretty much making this up as I go...

I know that as a Humectant it draws water up to the SC...but this has nothing to do with atmospheric humidity, right? I think I'm trying to figure out how butylene glycol would affect skincare products... like...does the resistance to humidity do anything when used in skin care products?

P.S. Thank you for all your hard work! I really appreciate it!
- Lane