Did you know you can thicken your liquid foaming surfactant based products with just ordinary table salt?
Examples of foaming surfactant based products are face washes, body wash, shampoos, bubbles baths. As long as it’s a liquid product that’s purpose is to create lather and foam and is made with an anionic surfactant, it can be thickened with Salt. BUT HOLD ON!
It’s only specific Anionic Surfactants that can be thickened with salt. Not all Anionic Surfactants will thicken with salt.
According to yeserchem.com it’s Alkyl Sulfates, Alkyl Ether Sulfates, Fatty Acid Isethionates, Fatty Acid Taurides, and Acyl Sarcosinates thicken from salt.
Acyl Glutamate & Sulfosuccinates do not thicken from salt.
List of some Anionic Surfactants that thicken from Salt;
Sodium Lauryl Sulfate (SLS)
Ammonium Lauryl Sulfate (ALS)
Sodium Lauryl Sulfoacetate (SLSA)
Sodium Cocoyl Methyl Taurate
Sodium Lauryl Sulfoacetate (SLSA)
List of Anionic Surfactants that don’t thicken from Salt;
Disodium Laureth Sulfosuccinate
Sodium Cocoyl Glutamate
How to thicken with Salt
It is really easy to use Salt to thicken. First you just want to make your foaming product. In this case we will call it a body wash. Add in your distilled water, anionic surfactant and you co surfactant. I recommend using an amphoteric surfactant as you co surfactant as amphoteric surfactants can help assist with the thicken process to create a better foaming product, in my opinion. Then lastly make sure you add in a preservative and any other ingredients like glycerin or botanical extracts. Just make sure you have you finished body wash made with all of it’s ingredients and make sure you have adjusted the pH.
Now you can start adding in your salt. Only add in 0.3% - 0.5% of salt at a time. If you add too much you can actually make the product thin again. So make sure you add in 0.3% - 0.5% at a time and mix it in and give your product a second to thicken. If it’s not thick enough add in another 0.3% - 0.5% salt, mix it in, and let it sit for a second. Keep doing this until you get your desired consistency. Make sure you keep track of how much salt you add in each time you add it in.
For my experiment I combined…
0.5% Liquid Germall Plus
77.5% Distilled Water
Then I ended up adding in a total of .9% Salt to get my desired viscosity.
So now I need to rewrite my formal including the 0.9% Salt in the formula.
Now my formula looks like this, as I take that 0.9% from the distilled water phase.
0.5% Liquid Germall Plus
76.6% Distilled Water
0.9% Salt
Salt Curve Test
It is also important to note that there is a limit to how much salt you can add. If you add too much, your formula will actually lose its viscosity. This is because micelles are constantly breaking down and reforming in our formulas. If you add too much salt then the micelles will breakdown way too quickly and not reform quick enough, thus causing the product to lose it’s viscosity. The large micelles are what’s creating the thickness in the product. So if they are breaking way to quickly and not reforming fast enough the viscosity will be lost. This is called the “salt curve” (see figure to right)
You want to make sure you are on the left side of the salt curve, meaning, don’t use the highest amount of salt possible because it will be way to easy to accidentally add in too much. (See figure to left)
I actually wrote a blog post /filmed a video talking all about Salt (sodium chloride) and how it can impact our formulas. Sodium comes up in so many situations while formulating. So please check out the blog post that I think you will find extremely informative. Everything in this Salt Curve section was a copy and paste from that blog.
So if you choose to use Salt to thicken your surfactant system make sure you do a salt curve test. Keep adding in salt at 0.3% - 0.5% increments at a time until your formula starts to thin. Take note of how much salt it took until your surfactant system started thinning. Now you will always know to never of over that amount when formulation that specific product.
I actually tried to preform my own salt curve test and I literally added in a total of 4.5% salt and it was just a thick glob. It never thinned. So if it never ends up thinning, well I guess that can happen too. In this case, just take note of how much you added in when it turned into a gross glob. That way you know not to add that much salt.
Anyway, that is it for the thickening with salt lesson. Go watch the video version for a demonstration on how to thicken with salt. Also, below I just copied and pasted list of different surfactants that you can use to refer back to. Also if you want to watch a video all about surfactants to learn more about surfactants check out this video . Then this video here is a look at surfactants in a more science way.
Quick list of Foaming Surfactant
Anionic Surfactants
Sodium Lauryl Sulfate (SLS)
Ammonium Lauryl Sulfate (ALS)
Sodium Lauryl Sulfoacetate (SLSA)
Disodium Laureth Sulfosuccinate
Sodium Cocoyl Glutamate
Amphoteric Surfactants
Non-Ionic Surfactants
Sources;
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