Surfactants: A conditioning shampoo with SCI for normal to oily hair, Fatima asks: Can you tell me why another surfactant is needed? Wouldn't this work perfectly fine with just the two?
Great question! We use different surfactants blended together because each brings something different to the mix.
Take a look at decyl glucoside for a moment. It has good foam, but isn't known for its lather or bubbles. This wouldn't be a great addition to a bubble bath, but it might be good for a low lathering cleanser.
Let's take a look at disodium laureth sulfosuccinate (DLS). It has good foam and good detergency, and it's great for oily skin and hair.
If you take a look at this surfactant chart, you can see that something like C14-16 olefin sulfonate brings good lather, great flash foam, and good bubbles to the mix. It is good for oily hair as it removes sebum gently, and it's a good emulsifier. This would be a good inclusion for a shampoo, body wash, or facial cleanser for oily hair or skin.
If we wanted to make a bubble bath, we would be looking for ingredients that have great flash foam, great bubbles, and great lather. If we chose decyl glucoside as the only surfactant, we'd only have good foam. If we chose only DLS as the only surfactant, we'd only have good foam. So we would have a pretty lousy bubble bath. Instead, we'd want to use the C14-16 olefin sulfonate because it offers good lather, great flash foam, and good bubbles. We could combine it with SCI or ACI because both are known to have great foam, good bubbles, and good lather. This would bring us a great product that is better than the surfactants alone.
polyglucose/lactylate blend. It is a very gentle cleanser that offers great cleansing properties and a moisturized after feel. I think I'll add cocamidopropyl betaine as that surfactant will increase the mildness of the product and increase the viscosity. I might include some SMC or SMO taurate as it's also great for dry skin, and it works well in combination with cocamidopropyl betaine to increase viscosity.
Why use three different surfactants in this recipe? Because they each have something to offer to the product. The SMC or SMO taurate and cocamidopropyl betaine combination will bring mild cleansing and viscosity while the polyglucose/lactylate brings more gentle cleansing and a moisturized after feel. You could use two of three surfactants and have something nice, but I think using all three together offers something that is more special.
disodium cocoamphodiacetate, and SMC taurate together? What could I expect from the lather, foam, and bubbles? Would I have to alter the pH? What skin type would use this product? Think about those questions when you're buying your surfactants or planning to make something.
To get back to the original question - why use three surfactants in this shampoo?
CONDITIONING SHAMPOO FOR NORMAL HAIR WITH SCI
10% cocamidopropyl betaine
10% SCI (without stearic acid)
5% surfactant of choice (SLeS, SMC Taurate, a blend, and so on)
10% aloe vera
2% hydrolyzed protein
COOL DOWN PHASE
3% cationic polymer like honeyquat or polyquat 7
0.5% to 1% preservative
1% to 2% fragrance or essential oils
(up to 2% Crothix - when cooled down - optional)
SCI so very much. It makes my hair feel so conditioned after using it. But I can't use it huge amounts because it's a solid found in prills or pellets, and if I put in too much, it'll precipitate out. So I look to another surfactant to offer great cleansing as well, something like SLeS, SMC taurate, DLS, and so on. If I added SMC taurate, I'll be adding something that is great for thickening and dry to normal hair type. And I add cocamidopropyl betaine to the mix, I'll make it even gentler and help thicken the product well.
I guess I could use two surfactants - let's say SCI and cocamidopropyl betaine - but then I'd be losing the awesome power of the third surfactant. I could use just SMC taurate and cocamidopropyl betaine, but then I'd be losing the great bubbles, great lather, great foam, and elegant skin feel SCI brings to the party. By using three surfactants together, I'm bringing a few different awesome qualities to the product.
I feel like I've gone on too long here. The short answer is that by combining three surfactants I can create something that has the qualities I seek better than using one or two surfactants. Did I answer your question? I hope so!