Monday, February 14, 2011

Learning to formulate: Modifying your oil phase further

What if you want to increase your oil phase further? You have two choices - you can choose another recipe that has a higher oil phase and a lower water phase or you can modify your recipe to increase the oils and emulsifier.

Let's say we take the recipe from the other day, the less greasy spring time lotion for dry skin...

SPRING TIME BODY LOTION - LESS GREASY FOR DRY SKIN
HEATED WATER PHASE
39.5% water 
10% aloe vera
10% lavender hydrosol
2.5% sodium lactate
3% glycerin
2% hydrolyzed silk protein
0.5% allantoin

HEATED OIL PHASE
13% hazelnut oil
2% IPM
5% mango butter or babassu oil
3% cetyl alcohol
6% BTMS-50

COOL DOWN PHASE
1% fragrance oil
0.5% preservative
2% panthenol

...and we decide we need more emollients in the mix, as well as some silicones in the cool down phase. How can we go about doing that? 

So let's say I really like mango butter and want to increase it in this lotion to 10%. I could reduce the oils to 8% and make a more mango buttery lotion. But let's say I like my oils and don't want to decrease them - if I want to stay with 15% oils and IPM and 10% mango butter, then I have to recalculate my emulsifier amount.

So let's say I have 10% mango butter, 13% oils, 2% IPM, and 3% cetyl alcohol. I have an oil phase of 28%. (Click here to figure out what constitutes our oil phase.) If I go with the rule of thumb for Polawax, this means I need to have 7% emulsifier in this product (25% of the oil phase, so 7%). Add 28% to 7% and you have 35% for our heated oil phase. This means I need to reduce my water by 6% (5% for the increase in mango butter and 1% for the increase in emulsifier). This will produce a thicker product than our previous lotions. 

SPRING TIME BODY LOTION - LESS GREASY FOR DRY SKIN (increased mango butter & emulsifier)
HEATED WATER PHASE
33.5% water (reduced by 6%) 
10% aloe vera
10% lavender hydrosol
2.5% sodium lactate
3% glycerin
2% hydrolyzed silk protein
0.5% allantoin

HEATED OIL PHASE
13% hazelnut oil
2% IPM
10% mango butter or babassu oil
3% cetyl alcohol
7% Polawax

COOL DOWN PHASE
1% fragrance oil
0.5% preservative
2% panthenol

And let's say you really like the way cyclomethicone feels on your skin - it increases slip and glide and offers a feeling of powdery dryness - and want to include that at 2% in your cool down phase. We need to increase the emulsifier by 0.5% (1/4 of 2%) in our heated oil phase, and reduce our water amount by 2.5% (2% for the cyclomethicone, 0.5% for the increase in emulsifier). Even though it's in the cool down phase, it is still an oil soluble ingredient and needs to be included in our emulsification amount. 

SPRING TIME BODY LOTION - LESS GREASY FOR DRY SKIN (increased mango butter, emulsifier, and cyclomethicone)
HEATED WATER PHASE
31% water (reduced by 8.5%) 
10% aloe vera
10% lavender hydrosol
2.5% sodium lactate
3% glycerin
2% hydrolyzed silk protein
0.5% allantoin

HEATED OIL PHASE
13% hazelnut oil
2% IPM
10% mango butter or babassu oil
3% cetyl alcohol
7% Polawax

COOL DOWN PHASE
1% fragrance oil
0.5% preservative
2% panthenol
2% cyclomethicone

You'll notice with all our tweaking we're reducing the water amount every time. Which means we're now making a 60% water lotion (well, 59%) instead of a 70% lotion. Which is on par with a body butter or cream type lotion instead of a liquidy type lotion. (You can get 60% water liquidy type lotions, but they generally have fewer thickeners and butters.) This is why I say you can choose another recipe or just keep tweaking the same one. I find the 70% basic lotion recipe is a great place to start, but I generally end up in a very different place at the end! 

Join me tomorrow for tweaking lotions into creams! 

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