Learning to formulate: More fun with thickeners

I mentioned yesterday that increasing your thickening agents - like butters, fatty alcohols, and fatty acids - can make a lotion into a cream. Let's take a look at a 60% water lotion without thickeners, then consider what it would be like with different thickeners. Here's the recipe from which I will be working for this post...


SIX INGREDIENT LOTION WITH SHEA, SOY BEAN, AND SESAME OIL
HEATED WATER PHASE
39.5% water
20% aloe vera
3% glycerin

HEATED OIL PHASE
10% refined shea butter
10% soy bean oil
10% sesame oil
6% BTMS-50

COOL DOWN PHASE
0.5% liquid Germall Plus
1% fragrance oil (Clementine Cupcake)

Cetyl alcohol: If we remove 3% of the oils (any of the oils) and add 3% cetyl alcohol, this will thicken our lotion and offer some slip and glide to the product. Like all the other fatty alcohols and acids, it behaves as an extra emollient in the product. As a bonus, adding cetyl alcohol to a product with BTMS-50 as the emulsifier will boost the conditioning abilities, which could make for a more skin conditioning kind of product.

Cetyl esters: If we remove 3% of the oils and add 3% cetyl esters, this will thicken our lotion, but not as much as cetyl alcohol would. It will offer more slip and glide - thanks to the anti-tack properties - and you'll end up with a slightly thicker product than the original. (As a note, I think it's the cetyl esters that is morphing my vanilla based scents, so be careful in your fragrance choices.)

Cetearyl alcohol: If we remove 3% of the oils and add 3% cetearyl alcohol, we'll get a thicker, waxier feeling lotion than the original. It will feel more occlusive than a lotion made with cetyl alcohol or cetyl esters, and it will be thicker than either of these.

Stearic acid: If we remove 3% of the oils and add 3% stearic acid, we'll get a much thicker product than any of the previous ones with more drag and the possibility of the soaping effect. We'll also get a very tenacious cream, one that will offer a feeling of staying on the skin longer than those made with the fatty alcohols and esters.

What if I reduced the butter or replaced it with oils, what would these thickeners do? They'd thicken it! (Not meaning to sound sarcastic, but it's true!) If you have an all oil based lotion, adding 3% of one of these thickeners will increase the viscosity pretty dramatically. I'd say it's on par with adding 10% to 15%  butters to a product! And removing the thickeners will do the same thing. So if you have a body butter recipe you really love but want to make it into a lotion, remove the thickeners and see how you like it. You might still need to remove some of the butters - for thickness, as well for reducing the greasiness because 20% shea might feel great on your arms, but not on your hands - but you're on your way to creating a completely different lotion with a tiny change!

I remember when I switched thickeners for the first time. It was with a body butter recipe I found on the Dish. I didn't have any stearic acid, so I used cetyl alcohol. And the difference! It went from the consistency of whipped butter to being the consistency of Cool Whip! It felt much creamier and glidier, but it didn't feel like it stayed on as long as the version with stearic. I could really see the differences between the two products. Who'd have known that switching 3% of the recipe could make such a huge change in skin feel?

Join me tomorrow when we take a look at small changes making a big difference!