Tuesday, February 15, 2011

Learning to formulate: Modifying our lotions into creams

I find one of the quickest ways to turn a lotion into a cream is to substitute stearic acid for cetyl alcohol. Fatty acids tend to increase the thickness of our products better than the fatty alcohols, although you will experience a decrease in the slip and glide of the product and might even get some whitening of the product called the "soaping effect". (it will evaporate in time, don't worry).

As a note, you can make cream type lotions with cetyl alcohol - body butters are a great example of creams with cetyl alcohol - but stearic acid will make a thicker cream lotion at 3%.

Another quick way to create a cream is to use a ton of butters and few oils. If we look at our basic recipe, using 15% butter to 5% oil will create more of a body butter product than a lotion. Using cocoa butter or a cocoa butter replacement (like kokum butter) will create a thicker product than using something like shea butter or babassu oil.

So we can use the basic recipe and add stearic acid instead of cetyl alcohol and use more butters than oils to get a cream type product. Or we can start with a 60% water recipe or use the recipe we modified into a 60% recipe yesterday to make a cream.

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?

So let's say I want to make a foot cream for my normal type skin for the winter months. I want something very thick and moisturizing and I don't really care if it's greasy because I plan to wear socks. I want something that feels very luxurious and will stay on my skin until the morning. And I don't really care that much about slip and glide except for the few moments when I rub it on at night.

If we look at these goals, I immediately think about making thicker cream with stearic acid. So I turn to my 60% water recipe with stearic acid. (And yes, I realize this is technically a 63% water recipe...)

RECIPE FOR A THICKER CREAM 
WATER PHASE (63% of the recipe)
60% water
3% glycerin

OIL PHASE  (35% of the recipe)
15% oils
10% butters
7% emulsifier
3% stearic acid

COOL DOWN PHASE (1.5% - 2.0% of the recipe)
0.5% to 1% preservative
1% fragrance or essential oil blend

I could just make this recipe as it is and add some peppermint or spearmint essential oils as my fragrance component, but I want more humectants - I like lots on my feet - and I want to make some good decisions about my oils.

For the water phase, I want more humectants. Sodium lactate or sodium PCA at 3% or higher can be exfoliating, and that's always a bonus for feet! I'm not worried about being sun sensitive as I plan to wear this at night with socks, so I can include it at 3% or higher to get both the hygroscopic benefits and the exfoliation. So let's go with sodium lactate at 3%. (Plus sodium lactate isn't an expensive ingredient!) Remove 3% from the water amount to compensate for this inclusion.

I want to include some aloe vera for the film forming and soothing qualities, so let's add that at 10%. (Now we're taking 13% out of the water phase). Do I want a hydrosol here? Sure, why not. Feet always need soothing! I think I'll include some peppermint hydrosol as it increases circulation and the feeling of cooling. I'll include that at 10%! (So remove 23% from the water amount.)

I want to include some panthenol in my cool down phase, so I'll remove 2% from the water phase (now we're at 25% removed from the water amount).

MODIFIED WATER PHASE
35% water
10% aloe vera
10% peppermint hydrosol
3% glycerin
3% sodium lactate

MODIFIED COOL DOWN PHASE
2% panthenol
0.5% preservative
1% essential oils

For my oil phase, I think I'll keep it relatively the same, so I just need to choose my oils. I like soybean oil in a product like this - it's inexpensive, contains a ton of Vitamin E and phytosterols, and it's got linoleic acid, which is great for increasing skin's barrier repair abilities and reducing transepidermal water loss. For the butters, I could go with anything I want, but I find cocoa butter to be a good choice for a foot cream because it stays on your skin for quite some time and it acts as a barrier protecting product. (Remember, we're learning to formulate, so use any butter you like!) Click here for the emollient posts.

Oh, and I want some dimethicone in here as a barrier as well, plus it will reduce the soaping effect from the product. So let's add that at 2% in the cool down phase, and remove 2% from the oils amount to compensate for its addition (and I don't have recalculate my emulsifier if I add it to the oils amount).

Finally, I want to include some menthol in the mix. Menthol is oil soluble, so I'll heat the crystals in the heated oil phase. I will remove the 1% essential oils from the cool down phase as I really don't need them, and I'll remove 3% from the oils to make up for it.

So this means I've added 2% dimethicone and 3% menthol to the oil phase, and I'll compensate here by removing 5% from the 15% oils amount. So I'll use 10% soy bean oil instead of 15%. I'm not removing anything from the water phase at this time

MODIFIED HEATED OIL PHASE
3% menthol
10% soybean oil
10% cocoa butter

7% emulsifier
3% stearic acid

MODIFIED COOL DOWN PHASE
2% panthenol
2% dimethicone
0.5% preservative

So what about the cool down phase? I've already compensated for the inclusion of panthenol and dimethicone. Do I want to include anything else? Not really at this point. I've covered all the bases - humectants, extracts or hydrosols, silicones, and everything else - so I think my recipe is done! Let's take a look at it! 

FOOT CREAM WITH MENTHOL
HEATED WATER PHASE
35% water
10% aloe vera
10% peppermint hydrosol
3% glycerin
3% sodium lactate

HEATED OIL PHASE
3% menthol
10% soybean oil
10% cocoa butter
7% emulsifier
3% stearic acid

COOL DOWN PHASE
2% panthenol
2% dimethicone
0.5% preservative

So there we have it. As a note, check out yesterday's lotion and see how much difference there is. There's not much! Which just shows you that we could have started off with a 70% water recipe and decreased the water amount and increased the oils and emulsifier amount, and ended up in a similar place. 

Join me tomorrow as we modify this cream further! 

7 comments:

Bajan Lily said...

Hiya, I'm loving this series and plan to work my way through each one so I can see and feel the differences myself!
You may have mentioned this in a previous post, but can you explain the 'soaping effect' that you say dimethicone will counteract?
Thanks

Susan Barclay-Nichols said...

Hi Bajan Lily. Click on the link in the post for more information on this effect. It's quite interesting!

Bajan Lily said...

Ah-hah!

Rachel Katanga said...

great, I want to formulate a moisturizing cream for albino and people with sensitive skins, what raw materials must I use, please help.

Susan Barclay-Nichols said...

Hi Rachel! There isn't one ingredient that works for all skin types, so you'll have to do your homework on each ingredient. Check out the posts in the newbie section on making products and beginner tutorials, and look at the ingredient lists on the right hand side of the blog for ideas.

Let us know what you do next!

Dawn L said...

I'd like to use your thick cream recipe and add bentonite and kaolin clay to make it an exfoliating foot scrub. Can I simply add the clays to the finished cream at safe usage rates?

Thank you,
Dawn

P.S. I have learned so much from your blog and books. Thank you!

Susan Barclay-Nichols said...

Hi Dawn! I've written the answer to your question as today's Weekend Wonderings. The short answer is yes, you can. But read it for the longer answer!

And thank you for the lovely comments! I'm so glad I can be of service!