Mist me? Steam, spritz, mist - what's the difference and where do they fit in your skincare routine?
Updated: Jan 6
Interest in 'misting skincare' has risen 81% in the last year* (wow!!). But what are the benefits, and are all ‘airborne skincare’ tools created equally?
Ever since I uploaded my recent video about the Droplette, I've been getting lots of questions from my Facebook group, YouTube community, etc. about how Droplette's mist differs from the mist created by other skincare tools. From facial steaming to the simple 'toner in spritz bottle' to other devices such as the RÉDUIT, what are the benefits of skincare misting, and which tools best meet your goals and budget?
In order to provide a comprehensive response, I delved into the science. While it may seem relatively simple (I mean liquid misting through the air - straightforward, right?), I'm here to tell you it's actually extremely complex. Each of these 'misting modalities' is rooted in the branch of science called 'fluid dynamics' which is the study of how forces impact fluid motion. From the simple 'spritzing toner' all the way to scientists employing the latest medical research in today's devices, I've tried to simplify what is actually a massively complex topic, but this is a long blog. So click here if you want to skip to the summary info (no judgment!!)
You may have heard me mention it before, much of what we estheticians use in treatment room modalities have a root in medicine; lasers, microcurrent, LED and microneedling, all of these treatments got their starts thanks to research into applications for medical use. The area of using mist/vapour to penetrate tissues is no exception and each of these methods of creating vapour and sending it into targeted tissues began with a medical application of how to get therapeutic treatments to where they matter. I think that's so compelling not only because I find the 'medical histories' of skincare modalities to be fascinating, but also because I think it really validates the effectiveness of these tools for use at home. But not all of these tools have the same benefit - read on to learn about which ones might fit best into your skincare regime and budget. Each of these tools has its strengths when employed in your skincare routine. My hope is that this blog will help you appreciate each for their own wonder!!
Before we go too far talking about the specific tools, there are a few fluid physics terms that I need to touch on. I’m keeping it simple here (it really is complex!!) so please forgive me if you're a physicist and I’m oversimplifying it for you!!
Under normal conditions, drops of liquid tend to pool or ‘coalesce’. So as soon as a droplet gets near another droplet (which happens a LOT when we mist!!) there’s a seemingly magnetic force that causes the two droplets to merge, creating a bigger drop… and then another, and so on. When this happens on the surface (say of your skin), the droplets can be said to be pooling. Pooling is all well and good if you have a spill on a countertop, but not so much use if you’re misting a toner on your skin!! Effectively it doesn’t make a big difference how small your mister is making droplets if all those droplets create pool of water by the time they hit your skin!!
A Weber number >1 ensures that inertia is winning out over surface tension, meaning the droplets breakup rather than pooling.
(In fluid physics terms, Weber number means inertia dominates over surface tension so droplets do not coalesce)
Turbulent outbursts. When liquids flow they may have a ‘laminar’ quality (think water out of a faucet) or a ‘turbulent’ quality (think water out of a fire hydrant). ‘Turbulent oubursts’ describe the transition from a calm and orderly laminar flow to a disordered turbulent flow. It’s this transition - these manageable outburst of turbulence that create the environment for the droplets to become increasingly tiny.
When turbulent outbursts happen, they allow the droplets to ‘crash’ onto your skin without merging or coalescing into bigger droplets. Instead, under this "turbulent-transitional flow regime”, droplets create even smaller droplets in the process.
Just the right Reynolds number relative to the Weber number can create quite a force of droplets. With that as a foundation, let's move on to discussing some of the technologies and tools!
(in fluid physics terms Reynolds number is the ratio of inertial forces to viscous forces)
STEAM - THE MOTHER OF ALL MISTS!!
We know the ancient Romans started using steam baths to aid general well-being (including improving skin conditions) dating back to 6000 BC. The first reference to therapeutic delivery of airborne particles dates back to ancient Egypt (circa 1554 BC) when patients who were struggling to breathe were asked to inhale the vapor formed when black henbane plants were placed on hot bricks. By 300 BC, Hippocrates was using a device that treated a number of illnesses via inhalation of various vapors. While steam is sometimes used in modern medicine to augment treatments of respiratory issues, the heat of steam and its inability to be 'directed/propelled' safely in medical applications are limiting factors.
Steam as an aesthetic treatment was initially adopted in the early 20th century. Today's home steaming devices have a few more 'bells and whistles than the earlier models. Some have smaller outlets that allow you to channel the steam more specifically or offer 'ultrasonic vaporizers' to produce negatively charged ionic particles within the steam. Manufacturers claim that this makes the steam up to 10 times more effective at penetrating the outermost layer of skin, the stratum corneum.
Steam - the fluid physics component:
When water absorbs heat (from our tea kettle, facial steamer, etc.) its molecules become disturbed, causing the water to boil.
Steam is the gas formed when water moves from a liquid to gas state. H20 molecules break free from their bonds that keep them together. When water is in liquid form they're continually being joined and separated. But as the water molecules are slowly brought to a boiling point, the bonds that connect the molecules begin to break more rapidly than they can join. When heated enough, some molecules will break free forming a transparent gas that's called dry steam which you can see coming out of the tea kettle just before you see the wet steam. Wet steam is what's produced when enough water molecules give up energy into the air. Wet steam is, of course, what we know as the steam that's used during facials.
While I don't employ steam on a regular basis in my skincare regime, I do occasionally use steam at home to soften the stratum corneum before a desincrustation with a skin spatula.
Uses: Desincrustation, adjunct to a relaxing facial.
Pros: Steaming is inexpensive and can be quite relaxing.
Cons: Steam is vasodilating. This means that it can exacerbate conditions such as hyper pigmentation and rosacea. Also, steam can burn, so needs to be handled with care!!
Steaming doesn't 'open up' your pores. Rather, it softens both the dead skin of the stratum corneum AND the sebum and debris that may be lodged inside your pores. When all of this 'gunk' is softer it's much easier to remove.
I generally don't recommend steaming be done more than a few times a month on oily/acne-prone skin as there is some evidence that steam can actually activate sebaceous glands. I also don't recommend that you steam on top of sensitizing actives like AHAs + retinoids or in conjunction with enzyme peels as the steam can degrade the enzymes.
MODERN MISTING TECHNOLOGIES - OF PIEZOS AND PUMPS
What makes the difference as to how uniformly and deeply your skincare 'mists' are delivered to where they matter? Two things: how small the droplets are and how forcefully they're propelled. Putting steam aside, all of the 'misters' you'll use have one (or two) components in common: they have piezos and/or they have pumps. While they both can serve dual functions, for the sake of our discussion, piezos are primarily concerned with size of droplets and pumps with propulsion (but you'll see later where there's overlap!!)
The piezo. A piezo (aka piezoelectric transducer) converts electrical energy into extremely rapid mechanical vibrations - so fast, in fact, that it makes sounds that are too high-pitched for us to hear. These ultrasound vibrations can be used for scanning, cleaning, and a range of other tasks. But for our purposes, ultrasound piezos serve as mist-generating sieves.
The pump. This governs how the liquid is moved, against gravity, out of its container and how forcefully is it is propelled into the air and on/into your skin. Of course, we need to bear in mind that too much raw force is NOT a good thing. Needleless 'jet' injectors have existed in medicine for over 50 years (to deliver insulin, etc.) but have limitations, including compromising the skin barrier, risk of infection and bruising. Using this type of higher pressure jet on the wider facial area poses all sorts of risks. But it isn't just the raw strength of the pump that impacts how the mist will be created and delivered - it's also the sheer cleverness of it. More on this later.
PIEZOS - ultrasonic mist-generating sieves
In a different application, ultrasound has been employed for nearly fifty years as a method to administer medicines through the skin without the use of needles. Ultrasound in this context uses the energy of sound waves in order to drive the movement of chemicals through the skin by disrupting the stratum corneum. Intense ultrasound waves applied directly to the skin results in 'cavitation' which effectively temporarily opens little channels through which therapeutic chemicals can pass. I won't get into it here, but this application of ultrasound has its limitations within the skincare domain, namely, it can weaken already vulnerable cell walls as well as compromise the integrity of some more fragile chemicals that its meant to deliver.
But for the purposes of misting, a piezoelectric transducer works by converting high-frequency sound waves into energy that is then transferred onto a liquid. As the liquid leaves the atomising surface (pores) of the piezo, it’s broken into a fine mist of uniform micron-sized droplets. As you can see from the GIF below, the mist created natively by piezos does have some propulsion, but alone it isn't the kind of propulsion that enables the mist to penetrate the skin's layers. Below we'll cover three misting tools that incorporate this element: ultrasonic 'Nano' misters that you'll find on Amazon, the RÉDUIT and the Droplette. (Note: some nebulisers also use piezoelectric transducers to get medications into the tissues of the lungs - but the lungs don't have an equivalent to the skin's stratum corneum which provides a physical, chemical and immunological barrier from the outside environment.)
This 'lab piezo' was constructed with about a dozen parts as part of a physics experiment (not by me, but hey, I bet I could!) CREDIT: Edison Science Corner
(While pore density isn't the only determinant in the quality of a mist, it's one of the key factors.)
FLUID PUMPS - the key to fighting gravity and controlling velocity
Without a pump, vapor is just... well, vapor! It wanders, without much force, where the wind takes it rather than where we want it - on our skin. It's funny to think that only 30 years ago, pump bottles hardly existed in skincare but could be found under your kitchen sink (Fantastik spray cleaner anyone!?) But in the past ten years, in particular, we've seen everything from hair gels to sunscreens to facial toners packaged in the convenient pump spray bottle.
The atomizer has been in existence since 1890 when was invented by an Ohio-based physician, Dr. Allen Devilbliss. Devilbliss was a nose and throat specialist who was disillusioned by the unsanitary way he had to apply medicine via swabs. He developed a tool to spray his medicine directly where it was needed - into the back of patients' throats. By 1907 his invention had been customized for perfumes - many of us will remember seeing these perfume bottles on a grandmother's dressing table. In 1907 Devilbliss' son Thomas adapted his technology to develop the modern airbrush. In the 1940s cosmetic chemist Dr. Jules Montenier developed the first consumer product delivered with a plastic spray bottle. Stoppette, a deodorant that was applied by squeezing the bottle was a huge success, as previously deodorants were messy creams applied by the fingers. In the 1960s, the 'trigger pump bottle' that we know today came into existence. Below we cover three misting modalities that use a fluid pump: the spray bottle, airbrush applicators and the Droplette.
THE MODERN SPRAY BOTTLE
(click right for images of the internal workings of each device)
Spray bottles - the fluid physics component:
With spray bottles, hydraulics and pneumatics play a role in the fluid mechanics of creating the mist. When we press down on skincare toner spray dispenser with our finger, a small pump is immediately activated. The principal moving part is a piston that's located inside a tube. Inside the cylinder, there is a small spring.
To operate the pump, you push the 'actuator' (dispenser) which depresses the piston into the cylinder. The moving piston presses down on the spring, so when you release the button, the piston is pushed back out of the cylinder. The pump forces some of this liquid out through the tube into a much smaller nozzle, This tiny element has little channels that the liquid flows through to create the mist pattern - creating an aerosol of droplets. Et voila! we have a refreshing mist of toner sprayed across our face!
Uses: Best for a refreshing and even distribution of skincare intended for the surface of your skin (toners, essences)
Product penetration: Think of spray bottles as providing coverage rather than penetration. The mists created by spray bottles can help quickly and efficiently disperse a product, but the penetration of the liquid will be no greater than were you to apply it with your hands - no advanced physics here!!
Pros: Spray bottles are inexpensive and convenient ways to dispense skincare that has a low viscosity.
Cons: Manual spray pumps can be quite effective on the 'pump' side - we've all seen a stream of bathroom cleaner set to target getting the mildew out of shower corners. The limiting factor in skincare is that a strong stream of liquid doesn't help with absorption - we've all had the experience of 'pooling' or wet skin after using a simple pump mist.
Spray bottles are most commonly found as containers for toners. The low viscosity of toners and their role in hydrating and nurturing the stratum corneum make spray delivery ideal. I have a few of these misters and I like to use them to dispense my toners in or just for mineral water to use in conjunction with microcurrent.
A handy mister to dispense your toners/water into
"AIRBRUSH" APPLICATORS - the fluid physics component:
Mechanism: Modified pump
I recently noticed that Le Mieux (I love this brand!) had introduced a tool for helping to mist key skincare ingredients evenly across the face and neck. The device promises to help you 'bypass hands-on application of skincare products, evenly infusing micronized particles for immediate absorption.' If you've had a spray tan before or even used the popular Temptu airbrush for makeup application, you'll be familiar with the technology behind the Le Mieux tool.
(click right for images of the internal workings of each device)
Airbrush applicator - the fluid physics component:
The design of airbrush systems is pretty straightforward: It uses a physical principle named 'Bernoulli'. The effect of a pressure differential as the air emerges from the air cap draws the liquid skincare into the airstream; and the Venturi Effect, to accelerate and atomize the liquid, as it passes through the long nozzle. While the airbrush doesn't technically have a 'pump', when you squeeze air into a smaller space, you increase its pressure and store energy inside it. The pressure and stored potential energy of a compressed gas allow it to flow on its own without needing a pump. So effectively, the compressed air used by the airbrush skincare applicator is a bit like a gas with its own built-in pump.
I've been using a Temptu airbrush for years to apply makeup for the occasional special event. For sure, airbrushes do an amazing job at creating an even and fine film of makeup. There's no reason whatsoever not to use the same devices (for the same reasons!) for skincare. Many people may find the act of 'patting' a toner on their fact to be fussy and a bit of a nuisance. If you're one of them, the Le Mieux device or one of the similar options that can be purchased on Amazon are certainly worth considering.
Uses: Beyond the Le Mieux Ionized Oxygen Infuser, airbrush tools made for cosmetic use can be easily employed to diffuse skincare.
Product penetration: Equal to manual application of skincare with hands - the fine mist generated by an airbrush applicator will not propel your skincare any deeper than would be by patting on with your fingers (but it sure is fun to use!!) - the physics just isn't there.
Pros: These devices can be relatively inexpensive and fun! I know some people who like to assemble their own 'skincare concoctions' into one formulation and apply with a spray gun.
Cons: Cleaning the device can be a bit fiddly. You would want to pay attention to the oil/water balance as well as pH values of things you mix - but no more than you'd do if you were laying them on your face.
Tips: You'll want to watch the viscosity of the solution in the little cup - too thick and you'll end up having limited success.
Le Mieux Ionized Oxygen Infuser at SkinBeautifulRx. Get 20% off when you use code PENN20 https://skinbeautifulrx.com/collections/le-mieux/products/le-mieux-ionized-oxygen-infuser?ref=penn-smith
Amazon 'airbrush' dispenser (there are several out there, I'm not sure there's a big difference between them, so find the one that suits your budget.
'NANO' SPRAY - How they work - the fluid physics component:
'Nano' spray devices can be found all over Amazon, for as little as $5. They all have a piezoelectric transducer connected to a circuit board. As I mentioned above, the piezo transposes sound waves into energy that's focused on converting the liquid into a fine mist of droplets.
(click right for images of the internal workings of each device)
Uses: I think these are fantastic for spraying water on your face on a hot day (and boy has it been hot in Oregon!!)
Product penetration: A 'Nano' device that has piezo with a good quality mesh can create a very fine mist - almost looking like a fog. However, that 'fog' hasn't the force to go into your skin beyond the stratum corneum.
Pros: They're super inexpensive and easy to use - I always have a few of them around the house during summertime, and I've been known to bring a few as a 'hostess gift' to a summer party!!
Cons: You only need to read the reviews on Amazon to see that there is a huge range of quality in these inexpensive little devices. Also, some of the promises they make in their descriptions are a bit... let's say 'silly'. Many of the products suggest that you can use 'milk' in the device - not so sure about this (maybe they mean milky toners?) I'm also unsure about keeping the device clean, should you choose to use it with your own skincare, as the liquids seemingly interact directly with components beyond the piezo.
Tips: Mine has a built-in 'hydration meter' - I'm not sure how accurate it is in absolute value, but I find it fun to compare relative hydration levels during a single skincare session using multiple products.
FATUXZ Handy Nano Mist Sprayer
The Modified 'NANO', RÉDUIT - How it works - the fluid physics component:
Mechanism: Modified piezo
Like the Nano spray above, RÉDUIT uses 'ultrasonic diffusion' to deliver a mist to the skin. RÉDUIT differs in that it has capsules that contain mixtures of ingredients to achieve the desired effect. the RÉDUIT also purports to have a magnet that impacts the skin surface in some way, although I've not been able to establish the mechanism of action.
(click right for images of the internal workings of each device)
The company is focused on 'even distribution of concentrated products on the skin without the bulk or waste of traditional skincare'. Their focus isn't on 'product penetration' but rather uniformity of application and minimizing waste (fewer full-size serums/toners sitting on your shelf.)
Uses: Used for product diffusion across the skin surface.
Product penetration: While RÉDUIT employs ultrasound in an innovative way within the context of skincare, I can't see evidence that it aids in skincare product penetration in any significant way.
Pros: If you're a gadget junkie this could be a fun tool to try out. The company has haircare pods as well as skincare pods so there's a lot to play with!
Cons: While the company mentions that their 'pods' are recyclable, they don't have a 'send back' protocol. Each "pod" contains several components (including a piezo, chip, and different types of plastic), so I can't see that they would be easily recyclable in your local municipality. Also, while the company suggests that each pod should last about 30 uses, I found that I got only seven to ten uses, making the $18-$35 price tag a bit steep. Also, I found that the mist created by the RÉDUIT (I tried three capsules) seemed a bit less 'misty' than the other tools.
Tips: If you're interested in trying out the RÉDUIT you might want to look out for special offers, as they occasionally give the device for free as long as you're happy to buy three or four capsules. https://reduit.com/
Mechanism: Piezo, membrane pump
The Droplette was created by a team of scientists to address issues of getting medication directly to deep dermal layers inside cells without touching/harming the skin, or degrading the drug being introduced (they've succeeded in depositing pieces DNA inside cells while leaving cell walls safely intact.) It has an impressive history of development (nearly ten years) and future in medicine - among many other applications it's being trialed at Walter Reed Army Institute to optimize and treat soldiers' blast wounds.
(click right for images of the internal workings of each device)
Like 'nano' misters and the RÉDUIT, Droplette has a piezo. But it's a more finely tuned version that runs on a customized circuit board - the end result is that the Droplette piezo produces finer mist at a higher quantity. Importantly, Droplette's piezo can aerosolize more viscous things than other piezo-based misters (for example, the contents of the Collagen capsule.)
But Droplette's key differentiator isn't its piezo - it's its state-of-the-art (so advanced that NASA is funding further research in conjunction with the Droplette team) 'membrane pump'. The pump takes the mist created by the piezo and adds additional airflow - velocity - to the mist. So suddenly what was a 'normal mist' gets transformed into a high-velocity one that propels the capsule ingredients towards the skin. Additionally, when the drops hit the skin, the droplets actually break up upon impact, breaking up into even smaller droplets (0.37-2.1μm in radius) - hello Reynolds!). It's the speed of the droplets and the breakup affect that enables ingredients to get deep into the skin - where all of the processes are that help regeneration. The only way I can really get my head around this is picturing a 'bullet' which sort of squeezes down even very high molecular weight ingredients so they can penetrate our skin barrier without us even feeling it (I don't know why, but I think of the Pixar film The Incredibles!!).
This image displays the delivery of 100kDa RFP-tagged HA (hyaluronic acid) into ex vivo. The left size shows penetration when topically applied and the right Droplette-side demonstrates absorption into the dermis (note this is from a test in the lab - not using the current Droplette capsule contents)
Droplette is capable of generating an enhanced aerosol in a turbulent-transitional flow regime (thanks to Weber and Reynolds!) containing sub-micron droplets. It's efficient in delivering skincare to where it's needed (even very high molecular weight actives such as peptides.)
Uses: I use my Droplette every morning and every evening. I start the day with the Collagen capsule and finish with Collagen OR Retinol OR Glycolic, depending on the day of the week and how my skin feels (I'll use Collagen morning and evening if I'm using Tretinoin cream that night, for example). Other nights I skip the Tret and use the Droplette Retinol capsule.
Product penetration: The Droplette was created to help deliver medications to the dermal layers. This is no toy.
Pros: I've said it before - for product penetration, pleasure of use, and visibly improved skin, I love Droplette. I never have a day where I feel like skipping my Droplette. I can't say that about many things (other than maybe coffee!!)
Cons: The Droplette isn't inexpensive and the subscription plan requires a bit of a commitment. Also, the Droplette does not leave your skin all dewy with the glow of skincare left on the top layers. The glow I get from Droplette is clearly coming from deeper hydration and longer-term physiological changes thanks to actives getting where they need to be. I still use hydrators and occlusives after I use the Droplette.
Tips: Everybody I've spoken to has been really happy with the Collagen capsule. I think this is a great place to start - you can always add other capsules as time goes on and as they expand their range of capsule offerings. I ALWAYS use my Collagen capsule after I cosmetic microneedle.
US: https://droplette.io?sca_ref=689210.6BISA0R0Oc Code Penn75off for $75 off your first order
THREE MISTING DEVICES AND SOME CHICKEN BREAST
This is a little test I did with some chicken breast, blue dye, and three of the misting devices: Droplette, RÉDUIT, and the airbrush skincare dispenser. First of all, this was just for fun (who doesn't love to do science projects with their kids?!?!) Only the Droplette claims to penetrate into the tissue, so I'm not at all trying to discredit these other devices. Rather, I'm using them to contrast my Droplette results. The other thing is that no, of course, chicken breast (even with fascia intact) isn't a proxy for human skin!! Nonetheless, I thought it was a cool experiment.
With one exception, skincare misting tools on the market today belong to 'pooling regime'. Their job is to create a fine and even distribution of liquid across your skin, but depending on the device you choose and how close you hold the device, you may experience some wet patches/pooling. The important thing to note is that none of these devices adheres to principles of physics that would explain an ability to permeate skincare beyond the stratum corneum beyond what could be experienced applying directly with the hands.
You can expect most of these tools to be a bit better at hydrating your skin when compared to applying liquids by hand, but they don't offer deeper product penetration (beyond the top cell layers of the stratum corneum) vs. applying your topicals manually with your hands. That doesn't mean they don't belong in your skincare routine - I personally place a lot of value on the rituals that make up a pampering session. From steaming to massaging to masking to peeling - I LOVE the different sensations and phases of my daily routines.
The exception is Droplette which, thanks to the pump that takes the fluid that comes out of the piezo and essentially gives it a 'kick of velocity' (a really big kick). Rather than being in a 'pooling regime', Droplette's pump puts it in a 'turbulent-transitional flow regime'. The extra velocity turns that 'normal' mist that came out of the piezo into one that has truly unique fluid physics properties that enable it to penetrate the skin.
In the end, when we make skincare choices (and other choices!!) we need to look at our needs and our budgets. It may be after reading this (or skipping right to this summary), you've decided what 'misting tool' you'd like to have. Or maybe you've decided to get your hydration and skincare penetration from other non-mist modalities. But if like me, you're intrigued by how fluid physics can support your skincare routine, then hopefully this blog will help you decide with tool(s) are right for you.
Please join my private Facebook group for more information on misting and lots of skincare discussion and tips!
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