How solubilizers and emulsifiers work in skin care chemistry

What are Emulsifiers and Solubilizers?

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Many industries have certain terms they use to help make communication easier. This jargon is great if you already understand the meaning, but it can be confusing if you’re just getting started. Emulsifiers and solubilizers are important ingredients in making hair and skincare products, so it’s beneficial to know what those terms mean and how to identify those ingredients when reading the ingredient deck on your favorite products!

Emulsifiers

Simply put, an emulsion is the suspension of one liquid in another liquid. There are more technical definitions, but to explain what an emulsifier does, let’s stick with this simple explanation. Lotions, creams, and conditioners are all examples of emulsions. In these examples tiny droplets of oil are suspended in water.  If you were to take a bottle and fill it 1/2 full of water and then fill the rest with oil, you would quickly notice the two don’t mix. However, if you shake the bottle like crazy, suddenly you see a cloudy mixture form for just a couple of seconds before the oil and water quickly sort themselves and separate again.

In order to keep the oil suspended in the water, you need an emulsifier. Common emulsifiers include Emulsifying Wax, Cetearyl Glucoside and Cetearyl Alcohol, Glyceryl Stearate SE, and Cetyl Alcohol NF to name a few. There is quite a bit of science behind creating a stable emulsion, but sticking to the basics, in order to bind oil and water together to make any lotion, cream, or conditioner you need an emulsifier.

How Do Emulsifiers Work?

Emulsifying agents are soluble in both oil and water, accomplishing this by having one end of their molecule attracted to water (hydrophilic) and the other end attracted to fats/oils (lipophilic). When an emulsifier is added to an oil and water product, one end of the molecule dissolves in water and the other in oil. Thus these water and oil molecules are forced to be near each other without separating out the way a salad dressing might do when left sitting. This push and pull of the emulsifiers in the oil and water keeps the different substances suspended in a solution.

There are a variety of types of emulsifiers, and choosing the right one means finding a molecule with roughly equal attraction to water and oils in your particular formula. This means finding an emulsifier with either:

  • positive charge (cationic) – best used with low acidic or neutral mixtures (with a pH of 7 or lower)
  • negative charge (anionic) – best used with alkaline mixtures (with a pH of 8 or higher)
  • no charge (non-ionic) – typically used on their own or with a charged emulsifier to increase stability

There’s a lot to learn about choosing the ideal emulsifier for your product, so we encourage you to read the individual descriptions or our available emulsifiers or check out this blog for more in-depth information.

Solubilizers

When something is soluble it means it is able to be dissolved in water. For example, sugar is soluble in water. When you add sugar to water and stir, it quickly dissolves and you end up with a sweet glass of water. Solubilizers, as they relate to making cosmetics, help to make otherwise insoluble liquids soluble in water. For example, if you wanted to make a body spray with essential oils, you could simply add essential oils to your spray, but you would have to vigorously shake your spray before use. This is why we highlighted how Acacia Gum is a great solubilizer for this purpose in this easy Perfume Spray Video.

You need a solubilizer to help keep the essential oils and water together, but this is not quite the same as emulsion. We want the oil to be soluble in water, not just in a mix of oil and water at a more even ratio.

Enter solubilizers! In the example of a perfume spray, you would mix your essential oils with a solubilizer before adding to your spray. This would prevent you having to shake before each use. Examples of solubilizers include Polysorbates, Safflower Oleosomes, and Propanediol. (Side note: Not to be too confusing, but often an emulsifier can also be a solubilizer depending on how it’s used in each formula).

How Solubilizers Work

Solubilizers are similar to emulsifiers in that they have both hydrophilic and lipophilic traits, but solubilizers tend to be completely water soluble and only a little oil soluble. In practice this means they can suspend smaller amounts of oils (think essential oils in perfume or room sprays), and because they are solubilizing only small amounts of oil the entire solution can still appear clear or lightly hazy.

You should use solubilizers when adding just small amounts of oil to a water-based product. When scenting a toner, a spray, a gel, etc., these can be your best friend. It will depend on the specific solubilizer and essential oil you use to determine the ideal ratio of product to emulsifier.

 

Now that you know what emulsifiers and solubilizers do and some common examples, you can better understand the ingredients in your hair and skincare products. Let us know if you have questions about emulsifiers and solubilizers, or if you’d like us to define other terms you’ve seen used.

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Penny F
3 years ago

If a solubilizer is changing an oil , does it change the function of the “good stuff” we are using it for?

B
2 years ago

Nice clear article.

QUESTION: I see these products being advertised online as” emulsifying cleansing oils or balms”. They are carrier oil (somethings with essential oils) that wash off with water.
—-> Would these “Cleansing oils” then be considered solubilizing cleansing oils instead?
—-> Is this misleading or the products they are using double up as both a solubilizer and emulsifier?
They are using products like polysorbate20, polysorbate80, and cromollient.

2 years ago
Reply to  B

FROM OUR CHIEF FORMULATOR:
Polysorbate of any kind and emollient (which is Di-PPG-2 Myreth-10 Adipate) are both water dispersible and soluble in most oils and esters. They work as not only applying an emollient feel (this is really what Di-PPG-2 Myreth-10 Adipate is used for) but also used to solubilize oils to water (mostly Polysorbate’s function).

The terms emulsifying and solubilizing often get used interchangeably which is not correct. So I would say these are solubilizing cleansing oils instead. An oil in water emulsifier does the same job as a solubilizer, as they both help to disperse oils in water since they don’t blend naturally. However, even though they are in the same group of surfactant molecules, they are different in every other aspect and should not be used interchangeably. See the reason I would not call these “emulsifying cleansing oils or balms” is because there is no oil in water emulsifier that is water soluble.

So you are correct in stating it’s misleading to state emulsifier

Az
1 year ago

Regarding differences in cleansing oils. Either polysorbate 80 only or emulsifying wax only (ie with the oils) would work interchangeably, even at the same percentages?

If so, what benefit do some people find in combining them in roughly equal parts in rinse off cleansing oils?

1 year ago
Reply to  Az

Hi Az,

I asked Teeneke her thoughts and this is what she said:

“Polysorbate 80 cannot be used interchangeably with emulsifying wax. I think the benefit of using both comes down to the stability and also viscosity of the final product.
The emulsifying wax will help suspend tiny droplets of oil in water where as the Polysorbate 80 will help the oil become soluble in water. Solubilizers work when there is a small percentage of oil to water. For example, if you have a water product such as a toner and want to add some essential oils for scent, a solubilizer is a good choice as it will generally not increase viscosity and you are most likely not going to use more than 1% essential oils. However, if you are wanting to add 5% essential oils or a carrier oil like olive oil, you will most likely need an emulsifier for stability. Adding an emulsifier will likely increase viscosity and will likely make an otherwise clear toner cloudy.”

Does this answer the question? Just reply to this comment and let me know if you need further clarification.

Cheers!
-Brandon Paul

Marie
1 year ago

Hello! Thank you for the info… I create essential oil sprays (for face and body) using just essential oils (3-4ml per 3.4oz), a natural preservative and polysorbate 20. I REALLY want to get away from using P20 as it isn’t as natural as I would like but I have no clue what else to use. I was going to try organic soy litchin but I was advised that it would not work.

If I am trying to make the “greenest” and most natural spray what would your suggested emulsifier be to mix the oils and water together in mass production.

Ps- thank you so much for your time!

1 year ago
Reply to  Marie

Hi Marie! Brandon from EWL here.

Honestly, I would try Lecithin. The only drawback is the spray will be cloudy. One thing that is great about lecithin is that it is suitable for both oil and water. Experimentation is key, and you can find yourself using anywhere from 0.1% up to 8% depending on your formula. Another option is that our Propanediol is 100% bio based, green and renewable; you could use that in place of polysorbate. Again, experiment with the ratio but you might want to start with 1 part essential oil to 5 parts propanediol.

Doug
1 year ago

I am trying to solubilize Vanillin into solution so I can include it into a lotion. I have tried PG, IPM and DPG….and all precipitated (crystallized) out….after a few days. HELP…

1 year ago
Reply to  Doug

Hi Doug! Brandon from EWL here.

Have you tried ethanol? I think that’s the first place I would go. Make sure to warm up the vanillin and mix it until smooth with the alcohol. Experiment for your desired ratios but I think 2 parts alcohol to 1 Part vanillin is where I would start. Let me know if this doesn’t work and we can brainstorm further.

1 year ago
Reply to  Doug

I think this article was great and the comments! You helped me figure out a product i created for my hydro facial machine. I cant wait to try it! I trying to find something to break down propolis powder that will bind nice in a serum. Really didnt want to use alcohol any ideas!

1 year ago
Reply to  Hope G

Hi Hope! Brandon from EWL here.

Alcohol really is best for propolis powder, however if you truly don’t want to use it (although you won’t need much at all) you could try the solvent propanediol. I’d recommend warming the solvent up and try adding the propolis that way. I know some propolis powder is already created for water solubility, but you also need to make sure you use hot water. Please do share with us what you end up doing. We love learning from others.

Warmest Regards,
Brandon

Jordan
1 year ago

New to formulating so I need a bit more clarification. I’ll use liquid and/or solid bath oils as an example.
Obviously oils are not water soluble, so when formulators are making a bath oil, they use a solubilizer, like poly 80. I’m assuming you would need to specifically use a solubilizer rather than an emulsifier because you want the oils to be soluble in the bathwater.

What would be the differences between using a solubilizer vs emulsifier in a bath oil (or really bath products in general)? Would the emulsified bath oil just create a film on top of the water and/or create a tub ring? Just trying to understand reasons why you would or wouldn’t want to use one vs the other.

Thanks!

1 year ago
Reply to  Jordan

Hi Jordan! Brandon from EWL here.

It depends if you want to obtain a homogenous solution, emulsion or dispersion. In this case, you want to obtain a dispersion, which would require a solubiliser and not an emulsifier. Your assumptions of what an emulsifier would do is spot on in part, however another reason you don’t want to use one is because all emulsifying agents concentrate at and are adsorbed onto the oil:water interface to provide a protective barrier around the dispersed droplets.

Since you’re wanting just to bottle oil alone and not with the water, then you’ll want a solubiliser as the emulsifier will have nothing to actually adsorb to. Also an emulsifier, since it’s not water soluble, would require mechanical force to blend it and I doubt anyone would want to bring a blender into their bath! 🙂

Cheers,
-Brandon

Lynda
1 year ago

Hi Brandon!

Thank You so much for getting back to me on my question. I appreciate the simplicity of your explanation while at the same time giving me a precise formula and the reasons why. Yes, I do agree with you and your VP that only professionally manufactured sanitizers are the best and safest route to go, which was also pointed out by the person in that particular video that I mentioned above. She too echoed your very same warnings about DIY sanitizers and also recommended the WHO formula if one were to try a DIY. I just wanted to have something readily available in the event we are indisposed to soap & water; so I thought…heck, why not spruce it up a bit with scented and moisturizing oils. Still, it was thoughtful of you to extend the wise advice of hand washing and moisturizer after, as being the best alternative. I may be back in touch… But for now, have a lovely day and stay safe amid this pandemic.

1 year ago
Reply to  Lynda

Hi Lynda!

Thank you! I do hope we were able to help.

Stay safe and be well 🙂
-Brandon

1 year ago

Hi Guys! I have an all-natural (very few ingredient) distillate-based essence with EOs and wanted to use a gum (acacia or scelortium) as a solubilizer? Could this work? I don’t need a thick gel serum consistency and want to keep a slightly thicker water. Thanks!

1 year ago
Reply to  Amelia Regina

Hi Amelia!

Brandon from EWL here.

Since Acacia doesn’t really thicken as well as Sclerotium, perhaps give that one a shot. You will want to add a preservative I would think, though I do not know the ingredients of your distillates, some are preserved.

Cheers!
-Brandon

Nate S
1 year ago

Hi!

Thank you for the article. Can you recommend a solubilizer that would work best for adding fragrance/EO to liquid castile soap?I make liquid soap (Olive, Almond + Sunflower Oils with KOH) and have been struggling to get the fragrance to solubilize into the finished soap. I’ve tried both essential oils & fragrance oils and most don’t seem to blend well into finished soap. I have tried heating the soap to 120F prior to adding the oils + blending the oils with glycerin before adding to 120F soap without much luck. Can you recommend a solubilizer that would work best this? I was thinking perhaps Polysorbate 20, Caprylyl/capryl glucoside, or propylene glycol?

Thanks for your time.

1 year ago
Reply to  Nate S

Hi Nate!

Brandon from EWL here.

I would definitely try caprylyl/capryl glucoside first. Mix the essential oils into it first and then mix into the castile. However I have found that adding essential oils to alcohol and then adding that to castile via a high sheer mix actually works. Another option is thickening your castile with guar gum. Mix the guar and the essential oils and then add that to the castile.

Cheers!
-Brandon

Tina Harris
1 year ago

Hi, could I use an emulsifier if trying to incorporate MSM (crystallize) in carrier and essentials oils to make hair oil, if I mix the MSM with water to dissolve and then use an emulsifier to combine it with the oils? If so, what would be the best emulsifier? If not, do are there any other methods on incorporating the MSM.

1 year ago
Reply to  Tina Harris

Hi Tina!

MSM is fully water soluble. You could try heating up the thinnest of your oils in your anhydrous product and high sheer mixing the MSM into it. It won’t dissolve, but it might give illusion of such.

Cheers!
-Brandon

Raman
1 year ago

Hi Brandon, I recently purchased a business and one of the products it makes is sprays with essential oils.

I noticed the sprays are milky white and not clear. The essential oils are a little over 2% and they have been using polysorbate 20 as the solubiliser to blend the essential oil and water together. The ratio used is 1 part oil to 5 parts polysorbate 20. To me this sounds right and is also the recommended rate on the solubiliser bottle, but the product is milky white, and I think it should be clear.

Now that I own the business I did a small test where I doubled the polysorbate 20 so now I am using 1 part oil to 10 parts polysorbate 20. The result, it is much clearer, but still not 100% clear.

My question I need you help with is, can you have too much polysorbate 20 and is there something stronger I can use to reduce the amount of polysorbate being used to get the solution clear?

Thanks so much in advance.

1 year ago
Reply to  Raman

Hi Raman!

The cloudiness is because oil and water do not mix, which is why polysorbate is used as it is a solubilizer. Adding a solvent like alcohol will help break that issue of cloudiness down, which is why perfumes use alcohol as their base mostly. You can add too much polysorbate though because too much will cause skin irritation. Frankly you should expect the cloudiness and use the natural nature of essential oils to let people know why it’s cloudy.

Cheers,
Brandon

Michelle
1 year ago

Great article! You mentioned however, that unlike emulsifiers, solubilizers are used when your product calls for a lesser amount of oil. I was hoping you Could help me out with a few oil to water percentages or ratios. Thanks so much Michelle.

2 months ago
Reply to  Michelle

Hi Michelle!

Emulsifiers are not water soluble. Solubilizers are water soluble.

Emulsifiers are used to emulsify oils in water to create an oil-water emulsion. Emulsifiers are used for oils and lipophilic ingredients that have heavier molecules than essential oils. These oils include plant oils, fatty esters and waxes.

With solubilisers you can only incorporate low concentrations of a lipophilic ingredient, (0.1 – 2.0%). With emulsifiers you can incorporate up to 50% oil in water. (Note: most emulsifiers have an optimum oil phase concentration of between 15 – 30%.)

I encourage you to reach out to to our team to begin the consultation process by emailing info@ewlnatural.com or calling and (503) 893-1100 — I’m sure they can be a great help to you!

Cheers!
-Brandon

Nausheen
1 year ago

I want to infuse kojic acid dipalmitate in mct oil. I dnt want to only c8 c10 fatthy alcohals and ester or emulsifiers plz suggest the best solubliser for this.

2 months ago
Reply to  Nausheen

Hi Nausheen!

Kojic Acid Dipalmitate will often crystallize in cosmetic formulations.  It is recommended to add Isopropyl Palmitate or Isopropyl Myristate and heat until the Kojic Acid Dipalmitate fully disolves.

Cheers!
-Brandon, Essential Wholesale & Labs

Oly
2 months ago

Hello,

I came across your post. It was very informative. With regards to solubulizer, can I use olivem 300 as a solubulizer for hair and scalp leaving spray? In addition, I have NatraGem S140 NP Ecocert solubilizer are both Okey for leaving hair spray?

Looking forward hearing from you

Thanks,

Oly

1 month ago
Reply to  Oly

Hi Oly!
I asked Teeneke and here is what she said:

I don’t know these ingredients and would have to research this. At first glance, I would say try it and see.

Cheers!
-Brandon