by Marie | Feb 17, 2023
What does air bubbles in lotion/creams look like?
If you’ve ever packaged up a lotion in a clear bottle and noticed lots of air bubbles appearing up against the side of the bottle a day or two later, that’s air bubbles. Or perhaps you’ve made a thicker cream, you package it up, and it collapses and dramatically reduces in volume in the following days—that’s also due to air bubbles.
Why are there air bubbles in my lotion?
Very basically, they’re there because you put ’em there during the blending/stirring process. The thicker an emulsion is, the easier it is to incorporate air as you mix it. Here are some tips to reduce the amount of air you work into an emulsion as you make it.
Tip #1
Make sure the tool you are using to blend the lotion is designed for puréeing, not incorporating air. If you’d use a tool in the kitchen to whip cream, do not use it to mix a formulation unless the goal is to whip air into that something. This is why we use an immersion blender (a tool designed to purée) for lotions, but electric beaters (a tool designed to incorporate air) for making whipped body butters and other whipped formulations.
If your immersion blender has interchangeable blades, choose one of the flatter ones. The flatter/lower profile the blade is, the less likely it is to poke up over the surface of the mixture you’re blending (which will blend in more air).
Tip #2
Stop blending the lotion while it’s still too thin to support air bubbles and switch to gentle hand stirring. I typically find a 40–60 seconds of blending (followed by near-constant hand stirring until the emulsion thickens up) is more than enough to create a stable emulsion.
If the emulsion is still very fluid/thin, it won’t be able to support any air bubbles—they’ll just float right out. Continuing to vigorously blend/stir a lotion when it has thickened up will incorporate air into it, and it’ll be able to stay there because the lotion has enough structure to support that air.
This tip is more important for thicker emulsions; if you’re making a thin body milk you can blend away to your heart’s content as the emulsion will never get thick enough to support air bubbles.
Tip #3
Keep the immersion blender head submerged when it’s running; don’t pump it up and down. If you feel like you need to pump the blender up and down, that’s a good sign your emulsion is thick enough that you should’ve stopped blending a while ago. Only use the blender while the emulsion is thin enough that it’ll circulate around the moving blades easily.
Similarly, don’t stir super vigorously one you switch to hand stirring—keep the emulsion moving, but if your stirring method looks like something you’d do to prepare eggs for scrambling, calm it down 😄
Tip #4
Make sure your tool is submerged in the emulsion as you’re blending. You need to be able to submerge the entire head of the immersion blender in the emulsion; if it’s poking up above the surface, that blade will be able to grab air and blend it into your emulsion.
Ensuring submersion is typically going to depend on 1) batch size, 2) beaker size, and 3) blender size.
The wider the head of your immersion blender is > the wider your beaker needs to be to fit the blender > the larger your batch size needs to be in order to submerge the blender head.
My Braun immersion blender is 6.6cm across. This wide enough that the minimum batch size that will submerge it is 100g (3.5oz).
My Bamix immersion blender is 5.6cm across; this is narrow enough that a 50g (1.76oz) batch will submerge it.
Learn more about my blenders: Immersion blender in the free Humblebee & Me DIY Encyclopedia
by Marie | Jan 14, 2022
This is mostly personal preference; I find the water phase comes out of its measuring cup more easily and completely, so I do it this way. If you prefer to do it the other way around, go for it. It usually does not matter. If the formulation uses Polawax, Emulsifying Wax NF, Olivem 1000, Ritamulse SCG (Emulsimulse, ECOMulse), BTMS-50, BTMS-25, Glyceryl Stearate SE, or Glyceryl Stearate (and) PEG-100 Stearate as the emulsifier, I’m quite confident that you can pour whichever phase as you desire and the formulation will succeed. I have probably made well over a thousand successful emulsions with these emulsifiers, pouring the water phase into the oil phase.
Some people believe that if you’re making an oil-in-water emulsion than you must pour the oil into the water and vice versa. This is not the case. The emulsifier the formulation uses determines the sort of emulsion you get—which phase is poured into which cannot change that. Some formulations/emulsifiers will specifically require that one phase is poured into the other. If that is the case for any of my formulations, I’ll make it abundantly clear in the instructions.
Try it!
by Marie | Jan 5, 2022
I’ve shared a ton of content about making lotion over the years, so I thought I’d collect the links into an FAQ for easy reference.
If you’ve never made lotion before, start with one of these formulations:
I highly recommend looking up the ingredients (especially the emulsifying waxes!) in the Humblebee & Me DIY Encyclopedia.
If you’d like to learn how to formulate your own lotions & creams from scratch, I highly recommend my DIY lotion workshop. It’s a digital formulating workshop that teaches you my 10-step lotion formulating framework that empowers you to create your own emulsion formulations from the ground up.
These resources will help you start to adjust pre-existing formulations and create your own:
If you are looking for one-on-one instruction, please consider becoming a top-tier patron over on my Patreon. My $50USD/month patrons get a monthly 30-minute video consult with me where we can discuss all things formulating
You might also consider becoming a patron at the “The Monthly Collection + Office Hours” tier; this tier includes two monthly “office hours” sessions. Just like office hours with a TA, you are welcome to pop into the call/meeting with any questions you might have, discuss any projects you’re working on, or just to say hi. The calls are not be recorded. You need Zoom (it’s free) to participate, but you don’t need an account; each session runs approximately 45–60 minutes. One session is typically held in the afternoon, and the other in the early evening (Calgary time; MT/MDT).
by Marie | Feb 26, 2021
I’m often asked about combining fats and surfactants. These questions usually come as variations on these two themes:.
Can I add a foaming surfactant to a fat-based cleanser (like a cleansing oil or cleansing balm) to add lather?
Fat-based cleansers like cleansing oils and cleansing balms are mostly comprised of oil soluble ingredients like carrier oils, fatty thickeners, and esters. They typically use fat-soluble surfactants for rinse-off; these ingredients allow the fatty ingredients in the formulation to mix with water so they rinse off the skin easily. Common choices include solubilizers like Polysorbate 80 and PEG-40 Hydrogenated Castor Oil, and emulsifiers like Emulsifying Wax NF and Olivem 1000. These surfactants don’t create fluffy bubbles, but instead make a low, creamy sort of lather when the cleansing balm or oil is mixed with water—this is why these products are sometimes marketed as “oil-to-milk” cleansers.
You can add foaming surfactants to formulations like this, but:
If you use a water soluble foaming surfactant like Sodium Lauryl Sulfoacetate (SLSa), Cocamidopropyl Betaine, Sodium Cocoyl Isethionate (SCI), or Coco Glucoside in a high-fat product like a cleansing balm, it usually won’t add much (if any) noticeable lather. This is because, for these sorts of foaming surfactants, fat inhibits lather. I have included a low percentage of solid foaming surfactants like Sodium Cocoyl Isethionate (SCI) in anhydrous cleansing balms in the past; in a formulation like this they boost rinse off, but don’t add noticeable lather.
Something else to consider is that because these foaming surfactants are water-soluble, you may encounter solubility/stability challenges. A solid surfactant like Sodium Cocoyl Isethionate (SCI) or Sodium Lauryl Sulfoacetate (SLSa) will settle out of a cleansing oil and will need to be suspended in a balm formulation. A liquid surfactant like Cocamidopropyl Betaine or Coco Glucoside will contain quite a lot of water (often upwards of 50%). Not only will that water likely separate from the oil in your formulation, but it also means your formulation is no longer anhydrous so you will need to incorporate a preservative into your product.
If you want luscious lather in high-fat formulations, you’ll need use a special type of surfactant that does lather in formulations with lots of fat. These are MIPA and TIPA laureth sulfates; they’re not natural, but they are super duper cool! The easiest one to purchase is LUMOROL K 5229 (INCI: Laureth-4 & MIPA-Laureth Sulfate & Propylene Glycol). You don’t need much to get good lather (I’ve found 20–30% is enough), and even less for a creamy rinse-off. I do find LUMOROL K 5229 is a really effective cleanser, so even at 4% it’s a bit too strong for my tastes for a facial cleanser.
Can I add fat to a hydrous foaming liquid cleanser to make it gentler/richer?
This sort of cleanser is powered water soluble surfactants like Sodium Lauryl Sulfoacetate (SLSa), Cocamidopropyl Betaine, Sodium Cocoyl Isethionate (SCI), or Coco Glucoside. These surfactants are diluted with water and can be thickened (with gums, salt, Crothix™ Liquid) or left thin and put in a foamer bottle.
If a surfactant-based liquid cleanser like a shampoo or body wash isn’t designed from the ground up to contain and support a meaningful oil content, adding oil to it won’t work. The oil will separate out as there won’t be an adequate emulsifier present. Compare this body wash formulation without oil to this body wash formulation with oil to see how different they are. The fact that oil inhibits lather also comes into play here; the oil in the formulation will reduce the lather the cleanser produces.
Of course you can incorporate an emulsifier so the oil will mix in, but once you start adding an emulsifier and oils to what began as a non-emulsified formulation, you’re changing it pretty dramatically. I wouldn’t say you’re making the same formulation anymore and are firmly in re-development territory. Emulsions containing foaming surfactants are also a challenge to keep stable, so be prepared to do lots of testing and experimenting to ensure it doesn’t split over time.
Happy formulating!
by Marie | Oct 26, 2020
The main difference between formulations that are designed to go in a pump-top bottle vs. a foamer-top bottle is the viscosity of the end product, so in order to make a formulation work in a different type of packaging, you will need to adjust the viscosity.
Formulations designed to be packaged in a foamer top bottle need to be very thin—usually somewhere around the consistency of water. If the formulation has even a hint of viscosity you’ll have issues dispensing it from a foamer top bottle. You’ll get lots of sputtering and will dispense fairly small amounts of uneven foam rather than the plentiful clouds of bubbles you wanted.
Formulations designed to be packaged in a more standard pump-top container (like the sort we’d put lotion in) need to be thicker—you’re probably pretty familiar with the consistency of more sorts of not-water-thin hand washes/body washes/shampoo and that’s roughly what you need. One of the many things you’ve probably encountered in 2020 is an un-gelled, water-thin hand sanitizer packaged in a container with a lotion pump, and it’s not a great experience. You get a great big splash of super-thin product that goes everywhere.
Want to make a pump-top formulation foamer-top friendly?
Remove the thickener. Depending on the formulation this could be a gum (or another gelling agent), salt, or Crothix™ liquid.
Some formulations may be too viscous on their own to work in a foamer-top bottle—if you’re making the formulation and it’s already thicker than water before you add a thickener, you won’t be able to put that formulation in a foamer-top bottle (this formulation would be an example of that—the Sodium Laureth Sulfate [SLeS] is so viscous that the product is too thick for a foamer bottle without any added thickeners).
Want to make a foamer-top formulation pump-top friendly?
Thicken it up! The easiest way to do this is with Crothix™ liquid. Gently stir it in at the very end; you’ll probably need ~3–4% to get the desired end consistency. Go slow, adding ~1% at a time and waiting between additions so you don’t accidentally create a solid blob 😂
For other ideas on ways to thicken surfactant products, check out some of my formulations for pump-top/squeeze-bottle friendly hand washes/ body washes/ shampoos. There are quite a few options!
by Marie | Oct 19, 2020
Probably! Here are some things to consider:
Which one?
Fragrance oils and flavour oils are different, and have different uses/purposes. Fragrance oils are used for body products except for lip products, and flavour oils are for lip products. Do not use fragrance oil in lip products. You can use flavour oils in other body products, but I never choose to.
How much?
Fragrance oils are a lot more potent than essential oils, and I usually find that 0.1–0.5% is more than enough to scent a finished product. That said, make sure you are paying attention to the documentation for your specific fragrance oil. Your supplier should list maximum allowable values for a variety of leave-on, rinse-off, and off-body products (like candles). Click here for an example. Some fragrance oils are formulated for candle use and will have a very low leave-on usage rate (or may not be allowed for on-skin use at all), while others are designed for the skin and will have a leave-on usage rate that is many times higher than you’d ever want to use (as in the linked example—72% in body lotion! 😳 That’s strong enough that your neighbours in your apartment building would probably be able to smell your lotion through the ventilation, ha).
For soap: the general rule of thumb is 30g (1.06oz) fragrance or essential oil per 500g (~1lb) of oils, but I find that’s a lot of fragrance and usually use closer to 20g per 500g. Make sure you are paying attention to the maximum values supplied by your supplier as well—those take priority.
How do I make room for it in the formulation?
If it’s a lotion, reduce the water by the same amount (using 0.1% fragrance? Reduce the water by 0.1%). If it’s an anhydrous product, reduce the most-used carrier oil by that amount.
For soap: if your soap was previously unscented you don’t need to remove anything from your soap to make room for fragrance oil.
Want to see the formulation adjustment in action?
Watch this video
Other considerations
- Tread very carefully with eye products; I usually prefer to scent them with hydrosols if I scent them at all.
- Surfactant products can behave very differently with different fragrance oils and essential oils. Check out this cool blog post from Botanical Formulations and this experiment I did to get an idea of all the things that can change! There are a ton of variables here—the surfactants, the thickener(s), and all the chemical constituents in your fragrance oil, so isolating the issue can be very challenging (but fun!).
- If it’s a soap, make sure you’re reading up on how your specific fragrance oil performs in soap. Does it accelerate trace or cause soap to seize? Does it contain vanillin, which will result in browning over time?
