4-lotions-with-different-fatty-alcohols

 

 

 

Differences between cetyl, cetearyl and behenyl alcohols

Jan 13, 2024 | The basics

I have always wondered what is the difference between fatty alcohols such as cetyl alcohol, cetearyl alcohol and behenyl alcohol in a lotion. All of them are very similar in structure, but can you actually feel the difference in a lotion? Let’s find out.

Difference between cetearyl alcohol, cetyl alcohol and behenyl alcohol in a lotion

1. FATTY ALCOHOLS – CETYL ALCOHOL, CETEARYL ALCOHOL, BEHENYL ALCOHOL

I had this idea of testing differences of cetyl, cetearyl and behenyl alcohols for quite a while. All of these ingredients are co-emulsifiers, all are fatty alcohols but they differ in their carbon chain length. Cetyl alcohol and cetearyl alcohol are very popular choices for thickening a lotion while behenyl alcohol is a pricier option. But what is the difference in a lotion when using these fatty alcohols?

To answer the question fully, we need to look into their structure first and see the similarities and differences. 

4-lotions-with-different-fatty-alcohols

2. What is cetyl alcohol, cetearyl alcohol and behenyl alcohol?

All 3 of these ingredients are alcohols, but they are not the same as ethyl alcohol. Here the word alcohol is used more in a chemistry context as all of these have the same functional group -OH, which is an alcohol group. However, the structure of the molecules differs in their carbon chain length:

– ethanol has 2 carbon atoms (short chain),
cetyl alcohol has 16 carbon atoms (long chain),
cetearyl alcohol has 16 and 18 carbon chains (because it is a mixture of two ingredients)
behenyl alcohol has 22 carbon atoms.

So, these are similar ingredients, but not quite the same. And this is why they should have similar, but still different skin feel.

Cetyl-alcohol-1

3. EXPERIMENT LAYOUT

To test the differences in the lotion, I have used a very simple lotion formulation. It is not suitable as the end product. To test everything out, I made 4 lotions in total. One without co-emulsifiers but with the same amount of lipids, and then 3 lotions with different co-emulsifiers with the same lipid content. For this test I have included quite high amount of co-emulsifier just to see how it will go. They are usually used in much smaller amounts.

The basic formulation:

KISS Lotion formulations

Ingredients Lotion without fatty alcohol Lotion with cetyl alcohol Lotion with cetearyl alcohol Lotion with behenyl alcohol
Water 72.3 % 72.3 % 72.3 % 72.3 %
Rice bran oil 22 % 16 % 16 % 16 %
Emulsifying wax NF 5 % 5 % 5 % 5 %
Fatty alcohol - 6 % 6 % 6 %
Cosgard 0.7 % 0.7 % 0.7 % 0.7 %

THE METHOD:

  1. Weigh A phase ingredients and B phase ingredients into different beakers and heat them in a water bath. Weigh the beaker with A phase ingredients and write down the number.
  2. Into a third beaker pour distilled water and heat it as well. It will be used for that water, that has evaporated during heating.
  3. Heat and hold for 20 minutes.
  4. Weight the A phase beaker and add distilled water that has evaporated.
  5. Pour A phase to B phase and homogenize for several minutes.
  6. Stir all the time while cooling down.
  7. Add C phase when the temperature of the lotion is less than 40°C/104°F.
  8. Pour into containers.
water-and-oil-phases-in-beakers
4-lotions-with-different-fatty-alcohols
Lotion-without-fatty-alcohol
Lotion-with-cetyl-alcohol
Lotion-with-cetearyl-alcohol
Lotion-with-behenyl-alcohol
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4. RESULTS OF EXPERIMENT

I purposefully did not include any coloring into a formulation to see if the co-emulsifiers will impart a glossiness, whiteness. All emulsions were left for 24 hours to set and only then tested. Also, I have to add that this is my personal opinion how they look and feel and your opinion may be a bit different. 

I have tested these 4 lotions:
– looked how they look (glossiness)
– checked the viscosity by mixing the lotion with a spatula
– rubbed a bit of lotion between the fingers
– put some lotion on the hand and spread it

4.1. GLOSSINESS AND VISCOSITY OF LOTIONS

From this experiment I could say that all emulsions look very similar. The viscosity looks similar as well, though lotions with fatty alcohols are a bit thicker. I would say that the highest viscosity would be with behenyl alcohol though. 

The exact difference in viscosity should be measured by viscosity meter, but as I do not have it, I can only say how it looks and feels while mixing. I have tried to capture the glossiness in the pictures, however it was quite hard to do and the lotions are glossier than they appear in pictures.

However, the glossiness of emulsions vary a bit. I would say that emulsion with no fatty alcohol is the shiniest of all four. Emulsions with cetyl alcohol and behenyl alcohol look very similar – they have reduced shine but they appear whiter and not so creamy.

Also, it seems that all emulsions with fatty alcohols have a bit more air mixed in compared to emulsion without fatty alcohols.

Lotions-with-cetyl-alcohol-cetearyl-alcohol-behenyl-alcohol

4.2. SKIN FEEL OF LOTIONS

All emulsions felt the same when rubbed between the fingers. The differences were felt only when rubbing on the palm. I have to address that how each lotion felt is my personal opinion

It is hard to compare the lotions as they felt very similar as well. The differences were not expressed that greatly as I thought it would be.

I liked the spread of the lotion without any co-emulsifiers the most as it glided nicely and I did not feel any dragginess afterwards. However, I felt the dragginess with the rest of the lotions and a highest drag was with behenyl alcohol. Lotion with cetyl alcohol had the lowest drag from these three lotions.

The rubbing time was long with all lotions with fatty alcohols. They glided quite nicely, but then after several seconds I could feel the immediate drag (stopping of the glide).

I would say that the richest lotion was the lotion with cetearyl alcohol or a lotion without fatty alcohols. After several minutes I could see that the area where lotion without co-emulsifiers was applied was shiny and felt quite greasy. It seemed like the lotion did not sink into the skin. But all other areas were matte.

The area where lotion with cetyl alcohol was applied looked kind of matte and powdery. It did not shine and did not feel greasy at all. And it felt kind of dry, even too dry. I did not feel this kind of dryness with other fatty alcohols. 

The conclusions of the experiment would be these
– behenyl alcohol had the highest drag, but also gave a dry, matte finish and it was probably the thickest lotion. And the whitest from all of the lotions.
– all lotions had a nice and long rubbing time and they were all glossy on the surface.
– lotion without fatty alcohol had the nicest slip, but it was greasy compared to other lotions and left the palm shiny. 

Lotion-without-fatty-alcohol-2
Lotion-with-cetyl-alcohol-2
Lotion-with-cetearyl-alcohol-2
Lotion-with-behenyl-alcohol-2

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