Tuesday, February 8, 2011

Learning to formulate: The water phase

As we know, there are generally three phases to our lotion - the heated water phase, the heated oil phase, and the cool down phase. Let's take a closer look at the water phase.

The heated water phase consists of water soluble ingredients that can safely be heated and held at 70˚C for 20 minutes. This includes water, hydrosols, aloe vera, hydrolyzed proteins, humectants, and some cationic polymers. The amount of water you include in lotion is key to the thickness of the final product. More water equals a thinner lotion; less water equals a thicker lotion (for the most part). 

As I mentioned yesterday, I consider a basic lotion to contain about 70% water, but we don't have to use all water for that phase. We can include water soluble ingredients that are liquidy like aloe vera and hydrosols, or we could include water soluble powdered ingredients like powdered forms of panthenol or sodium lactate or allantoin. 

So how to figure out when to include your water soluble ingredients? If your ingredient can tolerate heat, then add it to the heated water phase. If your ingredient won't tolerate heat, then add it to the cool down phase. (Click on the link for more detail.) Most of our humectants - glycerin, sodium lactate, sodium PCA - tolerate heat, but some don't, so check before using. Something like panthenol doesn't tolerate heat well, so add that to the cool down phase. Allantoin can be used in either phase, so choose the method you find produces the fewest shards. Some of our cationic polymers - like polyquat 44, polyquat 7, and polyquat 10 - like the heat, whereas honeyquat will give off an unpleasant scent when heated. (I try to include this information in every ingredient post, which you'll find to the left of the blog under "bath & body guides to ingredients" or in the "links to lists" section.)

As we work through this formulating series, keep in mind that we're working with percentages and every recipe should total 100% in the end. So when I'm talking about increasing the oil phase, I'm talking about increasing the percentage the oil phase takes up in a recipe. When I'm talking about decreasing the water phase, I'm talking about the percentage the water phase takes up in a recipe. For a recipe like my sample one, I'm using a 69.5% water phase and a 29% oil phase with 1.5% in the cool down phase for a total of 100%. If I increase one phase, I have to decrease the others to maintain that 100%. 

Finally, you'll notice that when I increase my oil phase I tend to decrease the water phase. This is so I can compensate for the increase in oil soluble ingredients and emulsifiers so the lotion is stable. So the water phase is more variable than the oil phase. But remember that if you decrease your water phase, you will make a thicker product. 

So let's take a look at the oil phase! 

11 comments:

Marnie said...

Great post. Just out of curiosity, what would Banana powder be considered as? I know it's water soluble, so am I to assume it's also part of the water phase or am I way off on that.

Susan Barclay-Nichols said...

Hi Marnie. Banana powder is an extract, and would be added in the cool down phase.

Marnie said...

Thanks!!

p said...

Hi Susan,

I'm confused by your second to last paragraph - wouldn't increasing your oil phase from, for example, 30% to 40%, necessarily mean decreasing your water phase (from 70% to 60%)? I think I must be missing the point of this paragraph.

Thanks,
P

Susan Barclay-Nichols said...

Hi p. That's what I'm trying to say in that paragraph. If you increase your oil phase, you reduce the water phase by the same amount. I'd like to re-write this so it's more clear - can you make some suggestions?

p said...

Maybe: "Finally, we're not bound to 70% water phase and 30% oil phase in our lotion recipes. If we want, we can increase our oil phase to 40%, which would mean decreasing our water phase to 60%, and this would result in a thicker lotion." Something like this? It might be clearer to speak in percentages?

It occurred to me that I was reading that paragraph while thinking in percentages, while maybe you were thinking in grams. Meaning, maybe you were thinking that if I increase my oil phase to 40 g from 30 g, I would "tend to" decrease your water phase to 60 g from 70 g. I'm still confused by the your sentence about compensating (by decreasing the water phase) in order to create a stable lotion. After all, 40 g oil phase and 70 g water phase would still make a stable lotion. That's why I thought I might be missing something....

Susan Barclay-Nichols said...
This comment has been removed by the author.
Susan Barclay-Nichols said...

Hi p. I think you mean it the other way around! If I'm thinking about reducing the water phase to compensate for the oil phase, then I'm thinking in percentages because I wouldn't bother compensating if I were working in grams. (Okay, I would compensate, but a lot of people wouldn't!)

Here's a clarification post on the topic, and I've updated the post as well. Thanks!

Priya said...

Hi Susan, Thanks for your response to my nit-picking! Your writing is generally crystal clear - I've come to expect it and thus I feel entitled to write nit-picky comments when I'm confused! :) I am actually still confused why you wrote "so the lotion is stable," but I totally get the point of what you're saying, so the niggling stops now! :)

aileen kilfeather said...

Hi Susan, what about water soluble ingredients like the aloe 200x powder? Must I blend that separately and then add to my water phase or could I make my enter water phase an aloe blend by just adding 1/4 tsp approx.? effectively making my water phase a "super water" enhanced with the heat-safe water solub. powders?

Anonymous said...

Great post! Thank you for the wonderful information. My question is, do I add the oil in water while they are still semi heated? And if so, what about the non heat tolerating water solubles? When would I add them to the solution? Would that be a separate phase that gets added after the mis of O/W or would I just add it to the water stage at cool down then add the complete water stage to the oil?