Sunday, February 27, 2011

Learning to formulate: Light lotions

As I've mentioned before, a light lotion is one that consists of about 80% water and doesn't contain lots of butters or other thickeners. This is something you'd use as a body lotion or facial moisturizer as it's not sturdy enough to handle being a hand or foot lotion. It works out to about 80% water phase, 0.5% to 1% preservative, and 19% oil phase (the cool down phase comes out of the water and oil phase).

BASIC LIGHT LOTION RECIPE
HEATED WATER PHASE
80% water

HEATED OIL PHASE
4% emulsifier
15% other oily things like oils, cetyl alcohol, and so on

COOL DOWN PHASE
0.5% to 1% preservative

Pretty basic, eh? So let's do some tweaking within this basic recipe today, and then take it a few steps further tomorrow.

For our water phase, you know we can replace a lot of the water with some very interesting things like aloe vera, hydrosols, hydrolyzed proteins, humectants, cationic polymers, and so on. For the oil phase, we know we can use oils, butters, thickeners, and so on. And for the cool down phase, you know you can add extracts, panthenol, silicones, and so on. So let's figure out what we want to make!

What kind of product do I want to make? Is it a moisturizer, body milk, lotion, cream, or butter? For which body part is this intended? What kind of skin feel do I want? Do I have a specific outcome in mind? For what skin type am I making this?

We know I want to make a light lotion, so I think I'll make a light lotion for winter skin (since it's winter and the last time I made a detailed post about light lotions I made a summer product). I want something that's light and glidy and I'm not too picky about it being greasy because it should sink in quickly. Ideally I'll include some occlusive ingredients to help act as barriers to the outside world.

For light lotions, I'm generally concentrating on the water soluble ingredients to pack as many goodies into the product as possible, simply because I don't have a huge oil phase. I want to pick one or two oils at the most, and I want to maximize their qualities because I don't have a huge oil phase. So if I want something with anti-inflammatory features I could choose an oil full of phytosterols or I could use a hydrosol or extract that offer the same qualities. If I want an oil that feels less greasy, I could use a less greasy oil, an ester, or I could use BTMS-50 as the emulsifier. Because I have a small oil phase, I can't be using tons of oils to get the skin feel I want, so I have to rely on the water soluble ingredients more than with other products. (It's the same with moisturizers - focus on the water soluble ingredients to give your skin the benefits you want!)

I want to include aloe vera at 10% for its film forming and soothing benefits. For winter skin, I like to use either chamomile or lavender hydrosol for anti-inflammatory and soothing benefits. I think I'll go with lavender hydrosol today because I'm out of chamomile and use the chamomile as an extract at 0.5% in the cool down phase.

I want to include my humectants - let's say 2.5% sodium lactate and 3% honeyquat (it'll do double duty as a skin conditioning agent and humectant) - although I could use any humectants or cationic polymers I like. I think humectants are important in any lotion but more so in a light lotion or moisturizer because I'll be getting a lot of the moisturizing qualities from the humectants and film formers. Since I won't be including cocoa butter as a barrier ingredient, I think I'll add 0.5% allantoin to my water phase and 2% dimethicone to the cool down phase to take its place.

Oh, and I want to use some hydrolyzed protein as a film former and moisturizer in the water phase. Let's go with my usual 2%, but this time I'll use silk because it's a nice film former and moisturizer! And I want to add 1% fragrance.

We need to decrease our water amount by 29.5% to make up for the addition of these other ingredients. So our 80% water is now 50.5%. (We aren't removing 2% for the dimethicone as that comes out of the oil phase.) We still have 80% water soluble ingredients in this lotion in the form of water, aloe vera, hydrosols, humectants, cationic polymers, and extracts!

HEATED WATER PHASE
50.5% water
10% aloe vera
10% chamomile hydrosol
0.5% allantoin
2.5% sodium PCA
2% hydrolyzed protein

COOL DOWN PHASE
0.5% chamomile extract
2% dimethicone
0.5% to 1% preservative
1% fragrance or essential oil
3% honeyquat

For the oil phase, I think I'll use some esters today. I want something really light but occlusive, so I'm thinking I might use C12-15 alkyl benzoate as the main oil in my product. It's occlusive and light and will fix my fragrance, if that's what I want. Since this is a dry feeling ester, I don't need to include any IPM or IPP to reduce greasiness. If you don't have this ester, consider using a light oil like fractionated coconut oil, sunflower, safflower, soybean, hazelnut, camellia seed, evening primrose, or borage oil if you want a light feeling (click here for the emollients list). Some of these are dry, some aren't. If you want a drier feeling product with sunflower, soybean, or safflower oil, then add 2% IPM or IPP.

I think I'll add a little cetyl alcohol as I really do want some thickening, so I'll go with that at 3%. (Cetyl esters would be a great choice here, but considering I'm fairly suer this is the ingredient messing with the vanilla in my cupcake fragrance, I think I'll give it a miss. But it is a great choice for a light lotion if you aren't using a vanilla based fragrance oil!)

So my oil phase right now consists of 2% dimethicone (cool down phase), 3% cetyl alcohol, and 10% C12-15 alkyl benzoate. As we're still using 15% oil soluble ingredients, we don't need to alter the emulsifier.

HEATED OIL PHASE
4% emulsifier
3% cetyl alcohol
10% C12-15 alkyl benzoate

So let's take a look at our finished light lotion.

LIGHT LOTION WITH C12-15 ALKYL BENZOATE

HEATED WATER PHASE
50.5% water
10% aloe vera
10% chamomile hydrosol
0.5% allantoin
2.5% sodium PCA
2% hydrolyzed protein

HEATED OIL PHASE
4% emulsifier
3% cetyl alcohol
10% C12-15 alkyl benzoate

COOL DOWN PHASE
0.5% chamomile extract
2% dimethicone
0.5% to 1% preservative
1% fragrance or essential oil
3% honeyquat

If you want to alter this recipe - because that's what this series is all about! - then consider using a light oil in place of the ester. Something like sesame seed or rice bran oil would be great choices here because they offer tons of linoleic acid and phytosterols, and they aren't that heavy (although some might consider them greasy). Feel free to remove the dimethicone and use an oil in the oil phase instead. Leave out the aloe vera and hydrosols and use all water! The possibilities are endless. 

In the meantime, check out this light lotion recipe for the summer. Please note, the hydrolyzed protein should go into the heated water phase. This recipe was created before I knew that!

So let's look at a few possibilities for light lotion tweaks tomorrow. 

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