Glycerine vs Propanediol for Extracts: Testing With Surfactants

Here's installment 2 of my little propanediol/glycerine comparative experiment. Check the links at the bottom if you want to catch up and get busy with a bit more glycerine stuff.

I left you hanging on the last post (a little bit on purpose) because there are quite a few bits and pieces I wanted to cover.

Viscosity and Color 

After straining and bottling both extracts, they looked like what you see above. On the right propanediol and glycerine on the left.

The lighter color of the propanediol is matched with a viscosity that is almost like water.


The scent of these 2 is (obviously) strawberry, but there are differences in the characteristics of the strawberry-ness (if that's a word).

The glycerine extract has a summery, light, freshly-sliced strawberry scent while the propanediol has a more perfumed, sweeter, and almost candy-like strawberry quality. I would describe the propanediol extract as 'borderline synthetic'.

Adding to Surfactants

To test how they behave in a soapy/lathery environment, I decided to try a very simple combo of both extracts with some gentle surfactants I happened to have in stock.

Here's the stock list

  • Decyl glucoside
  • Babbasuamidopropyl betaine
  • Coco glucoside
  • Lamesoft
  • Plantapon
  • Iselux

And look what happened. Pictured is my fave color combo

If this reminds you of a lovely summery sherbet ice cream, I would tend to agree with you. And it has the strawberry-fruity scent to match.

But check the difference in the bottles. These are photographed directly after pouring.


On the right is the bottle with propanediol extract. It floats on top while glycerine is happiest at the bottom of the bottle.

After giving both bottles a shake,  this happened:

Major color difference!

And after 24 hours, they looked liked this.

If you think the propanediol bottle is slightly darker, you would be correct.
The overall viscosity is runnier, but the kicker is the scent.

I passed these bottles around the family for nose testing and the results came back unanimious:

Propanediol Extract

  • not as strong a strawberry scent as the other one
  • smells a little candy-like


  • Mmmm, I want to eat this 

And Then...

Over the next couple of weeks, this happened.

Extreme color morphing! The propanediol went back to almost it's original color - opening up a whole slew of questions:

  1. What does this mean? 
  2. Why did this happen?
  3. Is this good or bad? 

All of which I am in the process of working on answering and promise to update as soon as...

Who knew such a simple comparative test could introduce so many new questions?

Do Tell

Do you use propanediol in your cosmetics? How do you incorporate it? Please leave a comment below.


Ilhem said…
Hi Lise! Thank you so much for sharing! It's fascinating and very useful. I'm looking forward to reading your update.
LisaLise said…
Hi Ilhem! Thanks for your comment — I promise to share! :)
Anonymous said…
This is very interesting. Looking forward to reading more from your website.
LaPalma said…
Hello! I just discovered your blog while searching for propanediol herbal extracts. I quite enjoyed reading the blog posts you wrote about your experiments comparing glycerine vs propanediol. I especially LOVED to learn that such topics are interesting to other people and not just me. �� Thank you!!
Best wishes to you on all your endeavors.