It’s July and it’s lovely and warm here, so I thought I’d tackle a topic I get a lot of questions about—body butters and the wonky things they can do in high temperatures. It’s crazy disappointing to make a lovely, soft, creamy body butter and have it transform into a puddle of oily glop when left unsupervised. Now, as someone who lives in a part of the world where 32°C (90°F) is considered a heatwave, this isn’t a super common problem for me, but I’ve definitely had body butters perform unwanted metamorphoses when left in a hot car or a particularly potent sunbeam. So! Today we are talking about why body butters melt and what we can do as formulators to keep them as buttery and delicious as we intended.
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What is body butter?
There is no universal definition for “body butter”, but for the purposes of this post I’m talking about solid anhydrous (water-free) formulations that are primarily comprised of butters. These butters can be true butters, like shea butter and cocoa butter, or pseudo-butters that are based around hydrogenated oils. If you’ve ever seen a butter for sale and thought “huh, I didn’t know there was such thing as [blueberry/coffee/cranberry/aloe/etc.] butter”, chances are pretty good that it’s a pseudo-butter. Check the INCI for the word “hydrogenated” to confirm.
Body butters are usually presented in one of three ways: as a solid balm-like substance, whipped up into body-frosting decadence, or moulded into a bar (either free-standing or in a push-up tube like deodorant). They’re usually designed to melt on contact with the skin, but otherwise keep their original shape (whippy/solid/whatever).
I’d also say that body butters don’t typically contain high concentrations (20%+) of hardening waxes like beeswax and candelilla wax, but I say that as someone who formulates in Canada, where 21°C is a fairly standard ambient temperature. I have spoken with formulators from hotter parts of the world who do include hardening waxes in their body butters for improved thermal stability.
What does melting look like?
The most obvious melted body butter “look” is when it’s fully liquified, but depending on the formulation and the environment your body butter might not fully liquify. Sometimes you’ll see colour and consistency variations—perhaps a gooey centre and a harder surface. The body butter might have a separated appearance, with a visibly solid layer in a bunch of liquid oil. Generally, though, a melted body butter won’t look quite right—it might look really oily or like it’s split. Chances are fairly decent that if your body butter looks wonky and is way too soft, heat is (at least partially) to blame.
A description I sometimes hear about a melted body butter is that it’s “too wet”; conversely, I also sometimes hear that a body butter is “too dry” when the melting point is too high for wherever it’s living. So, if that sounds familiar, the melting point of the formulation might be the problem!
Why is melting body butter a problem?
Well, firstly, it’s just not what you wanted! If you’d wanted to make body oil you would’ve made a body oil, dagnabit.
Second—melted body butter can be really messy. Say you’ve packaged it in a jar—that’s great for a solid, but far less awesome for a liquid, which can slop out of a wide jar opening if opened unawares. Melted body butter can also make a really big mess during shipping; that push-up tube you poured your body butter bar in isn’t designed to hold a bunch of liquid oil and get shaken up like a maraca as it travels across three provinces in August.
And third; a melted body butter rarely returns to its original, intended state when it re-solidifies. Different formulations will have different chilling/cooling/setting needs, but those needs are rarely “melt it in the back of a hot car, shake it around randomly, and then re-solidify whenever the AC is on”. This can make for a newly solid body butter that is grainy, gritty, too soft, and/or un-whipped.
Why is my body butter melting?
TL; DR: Because it got too hot.
When we formulate body butters (and other anhydrous products), three temperatures (and how they interplay) are important to keep in mind:
- Human body temperature
- Ambient temperature (the temperature the body butter will live in)
- The melting point of the finished body butter
Human body temperature is more or less a constant, right around 37°C (98.6°F). That number definitely fluctuates throughout the day and between people, but within a fairly narrow range. Nobody is sporting a 53°C (127°F) core body temperature and having a good day.
Unlike body temperature, outdoor ambient temperature can vary a lot. However, since human body temperature is relatively constant, the temperatures that we find comfortable and choose to live in—where we set our thermostats—also tend to fit within a relatively narrow and constant range. I don’t think anyone is setting their furnace to heat their home to 45°C (113°F), or cranking their air conditioner up so their home is basically a giant walk-in refrigerator. Personally, I’m happiest in the 21–26°C (70–79°F) range. (Of course, we don’t always have a choice, especially when outside temperatures exceed what your dwelling was designed for. During last month’s heatwave, my home was upwards of 30°C inside as I don’t have air conditioning. In parts of the world where central heating isn’t common a cold snap can mean the temperature inside homes drops into the uncomfortably chilly range. Homes can and do get too hot and too cold for comfort and/or safety, and the ability to keep ones’ home at a constantly comfortable temperature is definitely a privilege.)
The melting point of a body butter is a huge factor in the experience of that body butter. Some examples to contextualize different melting points: coconut oil melts around 24°C (13°C below body temperature), and it liquifies almost instantly on the skin because the skin is so much warmer than the melting point of coconut oil. Shea butter melts right around body temperature (~37°C) and it is much slower to melt when massaged into the skin. The lower the melting point of a product, the faster it will melt on the skin, and the more likely it is to melt when temperatures increase (my coconut oil melts several times a year, while my shea butter never has).
How these temperatures interplay
When formulating body butters, we are aiming to create a product that is solid until it is applied to the skin, at which point it will soften and/or melt. Put another way, we want our body butters to be solid at room/storage temperature but liquid at or near body temperature.
If your ambient temperature is generally well below body temperature, as it is where I live, this gives you a fairly large range to formulate within. It’s not very hard to make a body butter with a melting point that is both above room temperature and slightly below body temperature when those numbers are 15°C apart. The warmer your ambient temperature, the smaller that range becomes. If we take a formulation developed for a 21°C ambient temperature that melts at 28°C and put it in a 30°C setting, the ambient temperature now exceeds the melting point of that body butter. That formulation that was designed to melt on contact with the skin is just… melted. All the time.
I generally formulate for around 21°C (70°F) as that’s about where I keep my thermostat set, and my formulations live (and are applied) indoors. It definitely gets both warmer and colder than 21°C where I live (in the last six months it’s been -31°C and 37°C and everything in between!), but I don’t store my body butter formulations in my backyard. If your home is regularly warmer (or cooler) than 21°C you may need to adjust the body butter formulations I share with that in mind. My formulations won’t necessarily all liquify for you, but they may be substantially softer or fail to whip without some tweaking.
Ambient temperatures can definitely match (and exceed) body temperature in many places (it happened here in Calgary late last month!). This isn’t something I have a ton of experience with; when I’ve spent time in hotter climates (Australia, Costa Rica) air conditioning was very common, so while it could get very hot outdoors, it usually wasn’t indoors (where you’d usually make, store, and use body butters). Indoor ambient temperatures higher than 21°C were common (~27°C or so), but indoor temps warmer than body temperature (37°C) weren’t. If the temperature you live in is regularly right around body temperature, you will have to do your own formulation experiments to create stable formulations that also melt the way you want them to—this just isn’t something I have a ton of experience with living in Canada.
So, the extended version of “it melted because it got too hot” is more or less “it melted because the ambient temperature it was formulated for was exceeded.” So… what to do if you live somewhere properly hot—some lovely place where my Canadian body butter formulations transform into body oils?
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How can I stop my body butter from melting?
There are several strategies you can employ to help keep your body butters from melting.
Keep in mind: if you are adjusting your formulation to raise the melting point for hot climates, it now won’t work quite as well in colder climates. If you have hot summers and cold winters you will likely need different body butter formulations for different seasons.
Get to know your butters and hardeners in your climate
As a formulator, it’s essential that you understand what your ingredients bring to your creations—and this means you need to know what they are like for you, where you work. Handle your butters and form your own opinions. Where I live, cocoa butter is brittle and shifts quickly from a hard, snappable solid to a rich and slippy liquid when massaged into the skin. If it’s soft instead of snappable where you live, that matters—especially if I’m sharing a formulation for a hard body butter bar that relies on cocoa butter for hardness. If cocoa butter isn’t hard where you live, that won’t work.
I also recommend doing your own ratio experiments with hardeners—your results may be dramatically different than mine.
Shift the fat balance
The first thing I’d try is shifting the fat balance to feature more higher melting point fats and less lower melting point fats. For instance, if your formulation is a blend of shea butter and a liquid oil, use more shea butter and less liquid oil.
Add a hardener
If shifting the fat balance alone isn’t cutting it, my favourite way to raise the melting point of a body butter formulation above and beyond the powers of bare butters is to incorporate a fatty thickener. Stearic acid is a favourite of mine for this purpose as it is already present in butters like shea butter and cocoa butter (so it already feels very buttery!). Stearic acid melts around 69.3°C (156.7°F), so it doesn’t take much to pull up the melting point of a body butter formulation. You can also look at other fatty thickeners, like cetyl alcohol and cetearyl alcohol. To get an idea of how much to use and what they’ll contribute to your formulation, please read through these experiments:
- A Quick Guide to Stearic Acid & Liquid Oil Ratios
- A Quick Guide to Cetyl Alcohol & Liquid Oil Ratios
- A Quick Guide to Cetearyl Alcohol & Liquid Oil Ratios
Once you’ve read through them, I highly recommend doing your own version of the experiment in your particular climate. Remember—these results are reported from an ambient temperature around 21°C! If your ambient temperature is 10°C warmer, you will get different results.
You could also look at incorporating a hardening wax.
- A Quick Guide to Beeswax & Liquid Oil Ratios
- A Quick Guide to Sunflower Wax and Liquid Oil Ratios
- A Quick Guide to Carnauba Wax & Liquid Oil Ratios
- A Quick Guide to Candelilla Wax & Liquid Oil Ratios
- I’ve done more—search “quick guide wax” here
Try including some solid ingredients that won’t melt
Solid ingredients like starches and clays won’t melt and will help reduce the oiliness of your end product; included a meaningful amount of them can give your formulation a bit of a thermal stability boost.
Stop whipping it
Whipped butters melt faster; consider re-formulating for an un-whipped product for a boost in thermal stability.
Store it somewhere with a stable temperature
As I discussed in my post on grainy body butters, be kind to your body butters when storing them by choosing somewhere with a relatively stable temperature. Avoid sunny windowsills and hot cars.
Re-formulate your butter into an emulsion
Emulsions are far more thermally stable than anhydrous formulations—that’s part of why the “body butters” sold by companies like The Body Shop are emulsified products rather than anhydrous formulations.
Here are a few emulsified body butter formulations I’ve shared for inspiration:
- Macadamia Vanilla Emulsified Body Butter
- Shealoe Emulsified Body Butter
- Cocoa Coconut Emulsified Body Butter
Like your favourite wool coat, maybe body butters are just a winter thing for you
Saving body butters for the cooler months is also a totally valid option. There are plenty of lovely summery things you can pamper yourself with, like body milks, shimmer oils, body yogurts, and lovely lotions!
What about melting during shipping?
This one is hard, and frankly, the best idea I have is one I’ve seen many times on Etsy: just don’t ship body butters when they’re likely to sit in the back of a sweltering delivery van on a steaming hot day. If you formulate a body butter that won’t melt at 47°C (116°F) when your recipients will likely be using them in temperatures 20–25°C lower, that product will be way too hard to use.
What about keeping it in the fridge?
I’m not super keen on this as fridges are pretty cold, around 4°C (40°F). For anything designed to do well at 21°C, that’s obviously far too cold—that body butter will be way too hard. Refrigerating a body butter can be a good way to keep it stable during a heatwave, preventing it from melting and going all weird on you, but you won’t have a great experience trying to use the body butter directly out of the fridge.
Alright, those are my hot weather tips! How do you formulate for the heat?