Question from Patreon: How can I make a shower gel concentrate?

In the September Patreon Q&A, Sally asked: How can i make a shower gel concentrate?  I want to be able I want to make a large batch using some sci which takes a long time to melt, then dilute and add a different fragrance when I want say 300 mls of product. Do I just melt and mix the different surfactants using little or no water?

This isn’t directed at you, Sally, but I don’t understand why people think melting SCI (sodium cocoyl isethionate) is so hard. It isn’t. You just need to choose the right surfactant to help dissolve it. You can add some anionic surfactants like disodium laureth sulfosuccinate, sodium methyl cocoyl taurate, sodium cocoyl glutamate, or sodium lauroyl sarcosinate. You could add an amphoteric surfactant like cocamidopropyl betaine or cocamidopropyl hydroxysultaine. Or you could add some non-ionic surfactants like polysorbate 20 or 80, decyl glucoside, lauryl glucoside, or PEG-7 glyceryl cocoate.

My first choice is always cocamidopropyl betaine because it increases the mildness of the surfactant mix! (As a note, I’m calling it cocamidopropyl betaine instead of coco betaine because they are, in fact, two different products. It’s a pain to type, but it’s a good thing to be accurate!)

When melting SCI in a double boiler, you want to melt it only with the surfactant that can help it dissolve best. (I wrote a post on this a few weeks ago, so check it out here.)

As a note, if you’re using the powder – I’m using this version from Windy Point Soap (Alberta) – it doesn’t need heating for things like shampoo bars, and only needs quick melting in a liquid product.

Also, why are people using so much SCI as the primary surfactant when it really isn’t that water soluble? Don’t get me wrong, I love this surfactant so much, but you’re lucky if you can get 10% in a formula without it solidifying. And you can’t do that with a non-powdered version very well. You can see the results of using SCI noodles in a body wash in this post.

Related links:
Chemists’ Corner discussion about SCI
Clariant’s data sheet on their versions of SCI (I use Hostapon 85, which is very easy to melt)
Excellent article on the solubility of SCI – I encourage you to read this science-y article as it’s really interesting. 

Okay, back to the question at hand. You can make a shower gel that you can fragrance later on in two ways.

1. You could make a concentrate that doesn’t contain water by making up something like this formula – I love this body wash, but there are so many different versions on this blog – without the water bits.

BODY WASH WITH SCI
HEATED PHASE
37.5% water
5% SCI
15% cocamidopropyl betaine
20% LSB (or other anionic surfactant of choice)
10% aloe vera
3% glycerin
3% condition-eze 7
2% hydrolyzed protein

COOL DOWN PHASE
2% panthenol
1% fragrance or essential oil
1% liquid Crothix (may not be necessary!)
0.5% to 1% preservative
colour, if desired

I’ve worked out the formula without the water, fragrance, colour, and Crothix thickener. The total is 60.5%. I divided each ingredient by 60.5, then multiplied by 100 to get the percentage. So I divided 5% SCI by 60.5% to get 0.0825. Multiply by 100 to get 8.25%. 
BODY WASH WITH SCI THAT DOESN’T CONTAIN WATER
SURFACTANT PHASE
8.25% SCI
24.8% cocamidopropyl betaine
33% LSB or other anionic surfactant of choice

REST OF THE STUFF PHASE
16.5% aloe vera
5% glycerin
5% cationic polymer, like honeyquat or polyquaternium 7
3.3% hydrolyzed protein

COOL DOWN PHASE
3.3% panthenol
0.8% liquid Germall Plus

This would be quite thick. You could add water to the mix – somewhere between 30% and 40% – as well as Crothix to thicken, if necessary, and a fragrance oil at 1% or so.

2. Find a formula you like. Make it in a big batch, then store it until you want to fragrance it. (Related link here in the FAQ.) I do this all the time as I like to change my body washes or shampoos with the seasons. (Right now, I’m all about the oatmeal, milk, and honey as it smells like marzipan!) Remember that fragrances can affect the clarity and viscosity of surfactant blends, so if you choose something that thins it out – like those that contain vanilla – you’ll need to thicken it up with some liquid Crothix at the end.

Related posts:
Surfactants & fragrances – viscosity
Surfactants & fragrances – clarity
Fragrances and our products

Related posts on using SCI in liquid products…
Experiments in the workshop with polyglucose/lactylate blend
Ridiculously moisturizing body wash with esters
Formula for a 3-in-1 shampoo, body wash, and conditioner
Orange & honey hand cleanser with SCI

And there are more on the blog if you do a quick search for them.
Other related posts: