Sunday, June 7, 2015

Why did my lotion fail?

The most common question I'm asked is "why did my lotion fail?" I thought we'd take a few days to look at the various ways a lotion could fail and how to fix it.

What is a lotion? (From Back to to the very basics: Lotion making!) A lotion is an emulsified product. It can be an oil in water mixture - meaning there's more water than oil - or a water in oil mixture - meaning there's more oil than water. We generally make oil-in-water emulsions. A lotion must have water, oil, an emulsifier, and a preservative. Without these things, you don't have a lotion.

What do we need for an emulsified product to succeed? (From this post: Emulsification, what's that then?) We need three things - an appropriate emulsifer, heat, and mixing. Without all three, you won't succeed.

We heat and hold our products for 20 minutes at 70˚C/158˚F to ensure they will emulsify well. We mix with a mixer or a stick blender to ensure the product is mixed well. And we use enough of an appropriate emulsifier to ensure the oil and water will come together.

So what happens when our lotions fail? (From this post: When lotions go wrong!) The oil and water phases are no longer combined, and you'll see that as separation. It could be very subtle, like the bottle in the picture at the top of this post, or it could be dramatic, like the cottage cheese looking product to your left. It could happen right away or it could happen over time.

Join me tomorrow as we take a look at what can happen when we don't use enough or choose the wrong emulsifier.

Related posts:
A slightly more in depth look at emulsification
Emulsifying systems: Polawax, e-wax, and BTMS-50
It's time to make lotion!
Epic lotion fail with Natramulse
A few questions about lotion fails
Question: Why did this lotion fail?
Troubleshooting a lotion fail...
Can I save a failed lotion?


Me said...

Hi Susan,
'It can be an oil in water mixture - meaning there's more water than oil - or a water in oil mixture - meaning there's more oil than water.'
I know that we generally make oil in water products and for the sake of argument, they would tend to consist of more water than oil. But, what about the Bancroft rule?
Sometimes I think I get all this but it just doesn't seem to stick..
The Bancroft rule indicates that it's the type of emulsifier that dictates if a lotion is water in oil or oil in water.

From a previous post of yours; 'The hydrophilic head is in contact with the water phase while the hydrophobic tail is in contact with the oil phase. The hydrophilic tail connects to the oil and the head protudes into the water connecting the two.'
So, if we use a water in oil emulsifier is the head protruding out into the oil and the tail connects to the water? And, if that is the case, if we use more water than oil, it will fail unless there is enough emulsifier to provide an amount of 'tails' to surround all the water? In which case there would be an overabundance of heads in respect to the amount of oil?
Am I even remotely getting this or am I over thinking it?
I envy those who just seem to 'get it'


Susan Barclay-Nichols said...

Hi Erin. I was trying to simplify things in this post, so I didn't mention that rule. In the grand scheme of things, we make oil-in-water lotions with oil-in-water emulsifiers. The Bancroft rule is interesting, but really doesn't add much to the way we make lotions.

If we use a water-in-oil emulsifier in an oil-in-water emulsion, it will fail.

This is a good explanation of the w/o lotions from Making Cosmetics. I encourage you to check it out!

Not that you shouldn't think, but unless you are going to make water-in-oil lotions, it really isn't that important. It's interesting, but it doesn't really affect how we make lotions. Check out that link above for lots of great information.