Hello everyone! 🙂
Today I talk about how to formulate a Solid Shampoo.
This is NOT a natural soap, it is a Syndet (synthetic detergent) made with powder surfactants and other ingredients. A normal soap won’t work well as a shampoo, no matter how many expensive oils you add to it or how much love you put into soap-making.
If you want to make a decent solid shampoo, it must be a syndet. 😉
The advantages of a shampoo bar are that it is compact, it doesn’t weight much, it is easy to use, easy to carry around (on a plane for example)… Yet, it is not at all common to find one in the stores.
The reasons for this are many but here are the main ones:
A Solid Shampoo is made with an extremely high percentage of surfactant matter (55%-85%) and this makes the production costs fly very high as well.
But this is not all: a shampoo bar looks extremely similar to a simple and cheap soap and therefore people don’t give to it even the same value they give to, let’s say, a fancy bottle of liquid shampoo (even if the liquid shampoo costs way less, to produce, than the solid one).
These two things, combined, already don’t make for a winning product…
But this is not all: as you know from the various posts about formulating detergents (you can find them HERE) such concentration of surfactant matter is extremely high and this doesn’t just make the production costs go wild, but it is also an issue for the formulator: a product with 60% Active Surfactant Matter can be very easily too aggressive.
So now that we know the challenge, let’s attempt to formulate a Solid Shampoo!
First of all we need powder surfactants: most of the recipes I have seen around as well as the only solid shampoo I have bought in my life, were made of a single surfactant. However, as you well know, surfactants need to be mixed together in order to give a milder result (and this is something we ABSOLUTELY need in such a product).
So, rule #1: create a mixture of surfactants.
Simply mixing compatible surfactants won’t still make the shampoo mild enough, so a good idea is to add incompatible surfactants: anionics + cationics.
They both won’t work at their best, which is quite a waste, but in the case of a solid shampoo bar it is really needed.
You could use, for example, BTMS or (like I did in this recipe) Behentrimonium Chloride. Avoid the liquid ones (like Cetrimonium Chloride) because you need the solid shampoo to be… well, solid! 🙂
You will need to add a thickening ingredient in order to be sure your shampoo bar will be actually “solid”: common ingredients would be cetearyl alcohol or stearyl alcohol (maybe even better).
Surfactants are emulsifiers as well and this product is packed with them; plus, the thickening agent (cetearyl alcohol) is also a co-emulsifier (if that was needed) so there is really no need to add any extra emulsifier (I have seen some recipes with ewax, well I wouldn’t add it here). 🙂
Now, finally, to the RECIPE (at the end I have added a little comment on the formula):
Cocamidopropyl Betaine 20% (this is the only liquid surfactant – it is needed to decrease the aggression of ionic surfactants. If you don’t have so many different powder surfactants it is still ok as long as you do have the CAPB)
Butters and oils mix 10% (I have used cocoa butter 7% and argan oil 3% – you can use whatever you like, but keep in mind that you need the shampoo to be really solid so try to use butters and not too many oils)
Behentrimonium Chloride 10%
Cetearyl Alcohol (I had a 50%-50% one) 3%
Fragrance Oil 1.5%
1) Measure the surfactants (excluding the cationic one for the moment)
2) Melt them – this will take longer than you might think; luckily the water of the liquid betaine will make the process faster.
3) Measure the butters, the cationic surfactants and the thickener (Behentrimonium Chloride and cetearyl alcohol are in the same becher on the right)
4) And add them to the magic cauldron 🙂
I didn’t melt them separately first, but I suggest you to do it! (it will speed up the process)
(Yes, it does look like a mess!) 🙂
5) Once all looks homogeneous, take it out from the hot bath and keep stirring slowly until it is not too hot anymore (check the temperature: around 35°C). At this point add the last ingredients (fragrance oil and preservative… I have added a drop of colorant as well)
6) Put the soapy paste into molds
7) The easiest thing to do is place the mold in the freezer until the solid shampoos are hard enough to be unmolded and let them dry for a couple of days before trying to use them.
This is a simple recipe without any “extra” ingredients. You could add some hydrolized proteins (1%-2% for example) at cool down, or even D-panthenol (not too much, cause anyway all these ingredients are washed off moments after).
How I have found this shampoo:
It had a very high wetting ability, with an extremely soft lathering made of small bubbles. This was very comfortable.
What my head didn’t like were the waxy and buttery ingredients: even if there were all these surfactants, I still felt like the shampoo wasn’t cleaning enough. Next time I will lower the percentage of butters and oils and see if the result is more balanced 🙂