Tuesday, December 28, 2010

Question: How to thin out a thick lotion?

Someone asks: Say you have a cream that came out too thick and you have to thin it. You measure out the water and just add? THEN how do you refigure the % of your original formula?

You cannot thin out a thick lotion once you've made it. If you add water to it, you'll mess up the emulsion and the preservative. Heating it up and adding more water will make our not-heat loving ingredients like preservatives, panthenol, silicones, and so on very upset and they may become de-activated or might give off a horrible smell or might mess up the skin feel. So if you've made a thick lotion and want it thinner, you'll have to make notes for next time that you wish to alter it.

Let's use my basic body butter recipe as our template here as it is a very thick creamy buttery lotion.

60% water
2% sodium lactate or glycerin

10% oils (4% light, 4% medium, 2% heavy, or just 10% of the oil of your choice)
15% shea butter (or butter of choice)
6% emulsifier
3% cetyl alcohol

0.5 to 1% preservative
1% fragrance or essential oil blend

So what's thickening this recipe? Two main ingredients - the butter and the cetyl alcohol. You can leave out the cetyl alcohol and increase the water amount by 3% and you could reduce or even eliminate the butter. (The emulsifier helps thicken as well - we can't remove it, but we can reduce it.)

Whenever you remove something from a lotion, add the different to your water amount. So if you choose to reduce your butter amount to 5%, add 10% to the water phase. You can use any water soluble ingredients you choose - aloe vera, hydrosols, a combination of things like panthenol or proteins, but you have to add the amount into the water phase to get 100%.

Plus you need to look at your emulsifier amount. If you are using Polawax, it's about 25% the oil phase. So if we remove the cetyl alcohol and reduce butter, we lose 13% of our oil phase, and it becomes a total of 15%. So 25% of that would be 3.75% emulsifier, but I'll round it up to 4. (If you're using other emulsifiers, you'll have to read the manufacturers' suggestions for usage rates.)

So let's take a look at our new recipe!

75.5% water
2% sodium lactate or glycerin
10% oils (4% light, 4% medium, 2% heavy, or just 10% of the oil of your choice)
5% shea butter (or butter of choice)
4% emulsifier
0.5 to 1% preservative
1% fragrance or essential oil blend

I've increased the water amount to compensate for the reduction in the other ingredients. This should make thinnish lotion.

Let's say you're modifying on the fly and decide to add 80 grams of water to this recipe as you're making it (or, as often happens to me, your hand slips). Total up what you used in the recipe and divide by the total amount to get your percentage. (For more detail on how to get the percentages in the lotion, check out this post.)

80 grams water
2 grams humectant
10 grams oils
5 grams shea butter
4 grams emulsifier
0.5 grams preservative
1 gram fragrance oil
Total 102.5

So divide each ingredient by 102.5 to get your percentage

80 grams water / 102.5 grams = 78.05 grams of water
2 grams humectant / 102.5 grams = 1.95 grams of humectant
and so on...

Or you can just live with it being 102.5% and recognize that if you make a 10 times batch of the stuff you'll get 1025 grams instead of 1000. (I do this for small amounts over 100%. If you're at 110%, you'll want to recalculate the recipe.)


Tara said...

I've been asking about this before but what about this base sold here http://www.voyageursoapandcandle.com/Skin_Cream_Starter_Base_s/336.htm that says you can thin out by adding floral waters or other ingredients?

Susan Barclay-Nichols said...

Hi Tara. Sorry for not responding before, but I tried doing some research on the product and I haven't been able to figure it out. The only ingredients listed are purified water, emulsifying wax NF, and preservative, and they say you can thin it out by adding ingredients at room temperature, which goes against everything I know about lotion making. I have no idea how it works and I've never tried the product, so I'm sorry that I can't comment on it. (I do like the fact that in the recipes, Voyageur reminds you to add more preservatives to the mix!)

Tara said...

No problem Susan. I've actually purchased some and it works pretty well, but well, I'd like to make it myself. I'll start working on it ;-)

M Richards said...

I have been trying to find a formulation for a lotion with a little more "playtime" than this recipe has, but I really like these ingredients. I read that dimethicone can give "glide" but is drying and has other factors which I am not fond of at this point.

For the next batch, I will be using water only.

Could you help me with formulation of a somewhat greasier lotion? Increase water? If so, by what percent and then decrease oils? by what percent? Would it help to adjust (increase?) shea butter?

Another change I will make to this recipe is to add Rice Bran oil. Should I replace the Almond oil completely with Rice Bran oil? or maybe lessen the percentage of Almond AND/OR Avocado and replace with the Rice Bran?

36.7% Goats Milk
36.7% Distilled Water
7% Almond Oil
5% Shea Butter
5% E-Wax
4% Avocado Oil
4% Stearic Acid
1.2% Preservative (Optiphen ND)
0.4% FO or EO

Thank so much! I have read so much of your material. I think I might be making the lotion formulating a little too difficult! I will get it....Michelle

Brett said...

Hi, I want to try making an after-shave style lotion. Can I swap out the water for a combination of aloe and witch hazel?

ToniMattTony said...

I have a cream that I want to thin out with water, when I add the water to the cream it never fixes well and leaves flakes and congealed particles floating around, if I let it sit for a month it comes together as one smith cream. Can anyone help me speed up this process? Thank you

hamsdale said...

I've just started out making my own lotions and this page was very helpful. Thank you. I'm looking forward to testing out some changes to my existing recipe. Last time I had a small amount of unemulsified water. I'm assuming that this was caused by me adding the oil part too quickly.