What is a Low Fog Machine?
Low Lying Fog Machines
When you think of an ethereal atmosphere, complete with swirling mists that cling to the ground, what comes to mind? Maybe it’s a spooky Halloween scene, an enchanting wedding dance floor, or a dramatic stage production. The magic behind these captivating scenes comes from the use of low fog machines, from the affordable consumer systems that use water-based fog fluid, to the hazardous and costly dry ice methods still used for large stage and screen productions.
These devices are the go-to tools for creating a thick, ground-hugging fog that lends an air of enchantment and mystery to any setting. Unlike regular fog machines that fill a space with a misty haze, low fog machines produce a denser, cooler fog that stays close to the ground, giving the illusion of floating clouds. They work well with uplighters and effects lighting such as a strobe to create a unique visual experience.
Whether you’re a DJ looking to add some flair to your set or an event organiser seeking to create a memorable atmosphere, understanding how low fog machines work and how to use them effectively can be a game-changer for your events.
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How Does a Low Fogger Work?
Low fog machines operate on a fascinating principle that involves cooling the fog produced so that it stays close to the ground. At the heart of most low fog machines is a regular smoke machine that heats a specialised fluid until it vaporises, creating fog. However, what sets low foggers apart is what happens next. The hot smoke is then cooled, usually by passing it over an ice compartment. Cooling the fog increases its density and lowers its temperature, causing it to sink to the ground rather than rise and disperse. This process creates that signature low-lying effect, perfect for a range of atmospheric effects.
There are two primary types of low fog machines: ice-based units and the larger sonic models. Ice-based machines are typically more affordable and portable. As mentioned they work by channelling the fog they produce through a chamber filled with ice, which cools it down quickly before it’s released. They will also have a slot rather than the nozzle you find on normal smoke machines, which allows the smoke to ‘pour’ out rather than in a concentrated burst.
For larger applications, the systems use a bed of sonic agitation devices which vibrate at high frequency while submerged in a mix of water and standard smoke fluid. This creates a large and consistent volume of fog which is blown from the machine using a fan system and dispersion hose. They work extremely well, though are physically larger machines, usually built into wheeled flight cases, so won't be suitable for everyone.
Both designs offer a great low-lying fog effect while remaining safe to operate and highly cost-effective compared to the more commercial options such as refrigerated machines or dry-ice systems.
Do Low Fog Machines Need Special Fluid?
One common question among first-time low fog machine users is whether these machines require special fluid. The simple answer is that low fog machines are quite happy to use any standard water-based smoke machine fluid, but benefit greatly from the use of a high-density fluid type for optimal ground-hugging effect. This type of fluid is formulated to create a much denser fog than standard, which enhances the low-hanging effect by making the fog heavier and less likely to disperse into the air.
Water-based smoke fluid or fog fluid is a mixture of distilled water and either propylene glycol or vegetable glycerin (or both). One is used to give the smoke its thickness/density during heating, while the other aids with dispersion, and carries any flavours or scents if added. It's a nearly identical liquid formulation to Vape fluid and the PG/VG content is easily tweaked to produce thicker or thinner smoke to suit different machine types and requirements.
Using the right fluid not only enhances the visual effect but also ensures the machine operates efficiently without clogging or other issues. The additional water used in sonic agitation systems must be distilled, as the minerals present in tap or bottled water will cause chalk-like deposits to form in the machine and stop it from working. This is not an issue for the ice though, as the compartments are after the mechanicals, so normal ice cubes are fine. So, while you might not need an entirely different fluid, opting for a high-density or low-fog-specific fluid will give you the best results.
Is Low-Lying Fog the same as Dry Ice?
At first glance, the effect of low-lying fog and dry ice fog might seem similar, but they are quite different in terms of how they are created and how they behave. Dry ice, which is frozen carbon dioxide, produces a dense white fog when it’s added to warm water, where it converts back to a gas. This stays close to the ground as it’s chemically heavier than air, and its freezing temperature slows its dissipation greatly even when used outdoors, where it will gradually disappear as it warms up. It’s still the standard for large theatre and film set use, though modern water-based systems are getting closer to the effect.
So why don't we just all use dry ice i hear you asking? Well, dry ice is extremely volatile for starters. From manufacture, it must be stored in an insulated cooler, and a 5kg block for example will only be good for around 24 hours. It needs to be handled with safety as it can cause frostbite if touched and has a risk of asphyxiation if stored incorrectly as it turns to back to carbon dioxide gas while it melts. It also costs around £40 for 5kg, which will only give you around 15 minutes of fog production.
In comparison, the water-based fog fluid used in low foggers is non-toxic, safe to store, pour, spill, and breathe. It requires no special storage or implements. A 5-litre bottle is around £15 and due to the level of control you get with a smoke machine, that can last anything from 10 hours of constant use to several months of lighter use. The fluid also has a shelf life of several years, so you can see why it’s become the industry standard.
For the majority of users, it's not really an option to even consider dry ice. The expense, inconvenience, and dangers are just way beyond what most people will want to deal with just to enhance their events or gigs, especially when a modern ice fogger or sonic system will get you similar results without all the fuss.
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Delving Deeper: Understanding Fog Machines and Their Variants
Fog machines are incredibly versatile tools that have found their way into various industries, from entertainment to safety training. Whether you're looking to create a spooky atmosphere for a Halloween party or add drama to a theatrical production, understanding the different types of fog machines and their specific uses can help you choose the right one for your needs. Here, we’ll dive deeper into the various fog machine variants, their applications, and how a DJ or event organiser can use them to create captivating effects.
The Classic Fog Machine
The most common type is the classic smoke machine or fog machine (they are the same thing), which produces a thick cloud of smoke that spreads throughout a space. These machines work by heating a water-based fluid, usually a mixture of water and glycol or glycerine until it vaporises and is forced out of the machine through a nozzle. The result is a large volume of fog that can fill a room or outdoor space, creating a visually immersive environment.
Fog machines are widely used in clubs, concerts, and stage productions because they are simple to use and effective at creating a dramatic atmosphere. They are a fantastic option for mobile DJs and live bands that wish to enhance their lighting rig. However, the fog they produce tends to rise and spread out quickly, which can be less desirable in situations where you really want the fog to stay close to the ground.
Haze Machines: Subtle and Atmospheric
For those looking to create a more subtle atmospheric effect, haze machines are an excellent choice. Unlike fog machines, which produce thick clouds, haze machines are designed to generate a fine mist that is almost invisible to the naked eye. This mist catches and amplifies light, making it ideal for enhancing the visual impact of lighting effects like lasers and spotlights, while not obscuring your vision in the way thicker smoke does.
Haze machines are particularly popular in the world of live music and theatre, where they help to highlight lighting rigs and add depth to the visual experience. The fine particles produced by haze machines are typically dispersed more evenly throughout a space, creating a more consistent and long-lasting effect compared to the dense, localised output of traditional fog machines.
Traditionally they worked by heating a mineral oil, which does give great results, but has the downside of leaving an oily residue on surfaces. These have mostly been replaced with water-based fluid models which create a similar effect without the mess.
Low Fog Machines: Dense Ground Coverage
Low fog machines, as discussed earlier, are designed to produce a thick, cool fog that stays close to the ground. This type of machine is ideal for creating dramatic entrances, enhancing dance floors, or adding an extra layer of mystery to a stage performance. It's that classic 80s pop video aesthetic, and a favourite of Halloween events, with the key to their effectiveness being their ability to cool the fog before it is released, ensuring that it remains dense and close to the ground.
Event organisers and DJs often use low fog machines during key moments of a performance or event. For example, they are a popular choice for weddings, where they create a “dancing on clouds” effect during the first dance. Similarly, they are often used in theatre to create an eerie or magical atmosphere, or a misty lake, for instance, making scenes more visually striking. When combined with lighting effects, low fog machines can transform an ordinary space into something truly extraordinary
Low Fog vs. Dry Ice: Which is Better?
The decision between using a low fog machine or dry ice depends on the specific needs of your event or production. As mentioned earlier, dry ice produces a similar low-lying fog, but it is more challenging to work with due to its need for constant replenishment and careful handling. Dry ice fog also dissipates more quickly as the dry ice sublimates and the fog warms up.
Low fog machines, on the other hand, offer far more flexibility and ease of use. They can run continuously as long as they have fluid and power, making them ideal for longer events or productions. The fog they produce can be adjusted by changing the type of fluid used or by adjusting the machine’s settings, giving you more control over the effect.
While they may not give identical results, it's close enough for most users that dry ice use is now rarely seen outside of film sets and large stage productions.
Choosing the Right Fog Fluid
The type of fluid you use in your fog machine plays a significant role in the quality of the fog produced. As discussed, high-density fog fluids are best for low fog machines because they create a denser fog that stays close to the ground. These fluids typically contain a higher concentration of glycol or glycerine, which increases the fog’s density and longevity.
For standard fog machines, the choice of fluid will depend on the desired effect. Regular fog fluids produce a thicker, whiter fog, while fluid designed for haze machines produces a much thinner and finer smoke. It’s essential to use fluids that are compatible with your machine to prevent damage and ensure the best performance. You can buy fluid pre-mixed and ready to use, or you may prefer to buy concentrated fluid to save on storage space, mixing it up when needed.
If you choose the self-mix route, it's imperative that you only use distilled water for making fog fluid. Tap water and standard bottled water is full of minerals and salts, which will clog up the internals of the machine and cause limescale deposits in the heat exchanger. It can destroy the inner workings of any smoke machine with even one use, so do not do it.
For special events or parties, you can give the fog a fruity smell and taste by mixing in a custom scent additive, and if you stick to water-based machines and fluid, you can always be sure your smoke is safe for use around both people and animals, and wont leave any residue behind, so is ideal for any situation.
Practical Tips for Using Low Fog Machines
To get the most out of your low fog machine, it’s important to consider the environment in which you’ll be using it. Since low fog is denser and tends to settle, it works best in cooler, more enclosed spaces where the fog can remain close to the ground without being disturbed by drafts or rising heat.
Control the ambient temperature: Low fog works best in cooler environments. If possible, lower the temperature in the room or venue to help the fog stay low to the ground.
Limit airflow: Avoid placing your low fog machine near doors, windows, or vents where drafts can disrupt the fog and cause it to disperse. A popular question is always if the machines can be used outdoors, and while technically they can, there often is little point as you have no control over the wind.
Use appropriate lighting: Lighting plays a crucial role in enhancing the visual impact of low fog. Experiment with different colours and angles to create the most dramatic effect. You can give white smoke a real depth easily, and some machines feature built-in LEDs specifically for that reason. Strobe lighting is highly effective with smoke and fog, as are UV lamps, and it's a good idea to experiment as much as possible to find the format that gives you the best aesthetic.
Test before the event: Always run a test with your low fog machine before the event to ensure it’s working correctly and to fine-tune the effect. This also includes regular maintenance in the form of cleaning the machine out after it’s been used. This can be done with a smoke machine cleaning solution if the system is misbehaving, or for general care, you can run the machine with distilled water. This will turn to steam and clean the fluid pipework and pump workings to remove any PG/VG remnants that can gum things up.
Conclusion
Low fog machines are powerful tools for creating memorable, atmospheric effects that can really enhance an event or performance. By understanding how they work and the different types of machines, choosing the right fluid, and using them in the appropriate settings, you can achieve stunning visual results to complement your lighting setup.