Coulomb’s law dictates that like charges repel and opposite charges attract. This is the concept behind the electrostatic disinfectant sprayer, a powerful tool that deserves a place in your disinfection arsenal.

Electrostatic sprayers have played an important role in the agricultural, paint, and automotive industries for decades. More recently, these spraying systems have gained traction as an effective method for disinfecting indoor areas, such as schools, homes, and health-care facilities.

How electrostatic disinfectant sprayers work

Electrostatic disinfectant sprayers are specialized spraying systems that apply a positive or negative charge to a liquid disinfectant, which can be any water-soluble chemical. Since most surfaces in the natural world carry a negative or neutral charge, electrostatic disinfectant sprayers typically apply a positive charge to the spray droplets to take advantage of the laws of physics.

Electrostatic versus conventional sprayers

The electrostatic spray system is the technology that applies a charge to the spray droplets. Air and liquid enter the nozzle under pressure. From there, they transform into droplets approximately forty to eighty microns in diameter. At the tip of the nozzle is an electrode that applies the positive charge to the droplets as they exit the spray gun.

Electrostatic sprayers differ from conventional sprayers in that the latter typically use a pump to create a fine aerosol mist from the liquid in the tank and do not add a charge. Garden sprayers are one example.

For electrostatic sprayers, the electrode and its associated voltage in the nozzle system determine the charge. Nickel, stainless steel, brass, and copper all appear in electrostatic spray nozzles for this purpose.

Cleaning versus disinfecting

Cleaning means removing dirt, germs, and other unwanted substances from surfaces by scrubbing or wiping. Disinfecting requires a chemical agent to kill germs. Technically, electrostatic disinfection does not clean. This distinction is important to keep in mind when formulating a cleaning and disinfection plan.

Any water-soluble chemical will work with electrostatic sprayers, but the Environmental Protection Agency (EPA) publishes a list of disinfectants that are approved for use with this technology. Some examples of EPA-approved disinfectants for electrostatic spray systems include quaternary ammonium, hydrogen peroxide, and hypochlorous acid.

Of note, the EPA requires disinfectants to include on their master label the devices approved for application of that particular product. This is important to remember when pairing a disinfectant with an electrostatic spraying system, since the new “charged disinfectant” that exits the sprayer requires its own testing for efficacy by the EPA.

Fine versus coarse droplets: size matters

Smaller droplets are more efficient in covering the target surface than larger droplets. They are also more susceptible to “drift” in the air.

However, in electrostatic spray systems, the repellant quality of the positively charged particles offsets the small size of the droplets. When released from the nozzle, the droplets will spread out in a uniform distribution instead of clumping together.

Because electrostatic forces are seventy times stronger than gravity, the spray droplets will adhere to surfaces in any direction. This “wraparound” effect is another powerful advantage of electrostatic sprayers compared to conventional sprayers and foggers.

Pros and cons of electrostatic disinfectant sprayers

The benefits of electrostatic spray technologies in the disinfection industry are considerable. Their usage has expanded well beyond the agricultural and automotive industries, where electrostatic paint sprayers and pesticide sprayers were popular. However, there are some downsides.

The pros of using an electrostatic sprayer

• Versatility. Electrostatic sprayers are far superior to conventional sprayers when it comes to reaching nonuniform and irregular surfaces, including doorknobs, toilet paper rolls, toys, phones, chairs, and light switches. Of note, viruses tend to lurk on these surfaces.
• Efficiency. The electrostatic spray’s fine mist requires fewer chemicals to disinfect large surface areas, which can save the user time and money.
• Environmentally friendly. Unlike some conventional sprayers, electrostatic sprayers can easily accommodate sustainable and eco-friendly disinfectants.
• Speed. Electrostatic disinfectant sprays can cover thousands of square feet in minutes—much faster than conventional sprayers, foggers, and mists. There is also minimum downtime after use, on the order of several minutes.
• Convenience. Electrostatic sprays are fast drying, and they leave no liquid residue.
• Ease of use. Cordless and battery-powered electrostatic sprayers allow operators to maneuver easily and quickly around the spaces they are trying to disinfect.

The cons of using an electrostatic sprayer

• Target limitations. Electrostatic sprayers cannot treat airborne pathogens because the charged droplets need a surface to adhere to. Additionally, the charged droplets won’t work on positively charged or insulated surfaces.
• Price. Electrostatic spray systems can be expensive, with pricing ranging from $500 for a handheld device to several thousand dollars for a cart roller.
• Invisibility. Spray droplets dry quickly and without residue, which can pose a challenge to operators trying to remember which areas they have already treated.

Optimal uses for an electrostatic disinfectant sprayer

Electrostatic disinfectant sprayers are a versatile option for many different types of consumers. While the retail price of electrostatic sprayers runs higher than conventional foggers and handheld spray guns, the long-term cost benefits involved in saving on disinfectant products and manpower often outweigh the downsides.

Where electrostatic disinfectant sprayers are most effective

Electrostatic disinfectant sprayers are particularly well suited for nonporous surfaces, such as floors, walls, furniture, and electronics. However, electrostatic spray systems are not a substitute for cleaning. In some situations, scrubbing and wiping down surfaces prior to applying a disinfectant is necessary, especially in high-traffic areas.

In these cases, cleaning the surface with standard techniques can enhance the effectiveness of electrostatic disinfectant sprayers, making for a powerful two-hit punch against common pathogens like viruses and bacteria.

Electrostatic disinfectant sprayer uses

Electrostatic sprayers have actually been around since the 1940s as a fixture in the automobile industry. The spray system applied a positive charge to the liquid paint as it left the nozzle. The result was a fast, effective, and reliable method of painting cars.

In the 1980s, the agricultural industry started using electrostatic sprayers to treat crops with pesticides. It was during this era that some sprayers used negatively charged electrodes to ensure adherence of the pesticide to leaves, which tend to carry a positive charge.

The disinfection industry, however, did not discover the power of the electrostatic sprayer until the last decade or so. In 2020, electrostatic disinfection methods rose to prominence with the onset of the COVID-19 pandemic.

During the pandemic, the CDC issued guidelines for large-scale disinfection of indoor areas, such as schools and health-care facilities. The EPA created a list of approved disinfectants for use against the SARS-Cov-2 virus. This list, called List N, includes seven products specifically for electrostatic disinfection.

Electrostatic disinfectant sprayers have thus adapted spraying systems from other industries for use in large-scale disinfection protocols. In this regard, the electrostatic sprayer has been a game-changer.

Where to avoid using electrostatic disinfectant sprayers

In general, surfaces benefit from rigorous cleaning with wiping or scrubbing prior to disinfection. If a surface is visibly covered with dirt, grime, dust, or grease, cleaning it prior to applying a disinfectant is paramount. This allows for better penetration of the disinfecting agent.

Electrostatic disinfectant sprayers are less effective on nonporous surfaces, such as carpets, rugs, drapes, and clothing. These materials benefit from traditional laundering and cleaning techniques prior to the application of the disinfectant.

Of note, most bacteria and viruses carry a negative charge, but that doesn’t mean these pathogens avoid all contact with negatively charged surfaces. Viruses, for example, adhere to surfaces through Van der Waals forces and electrostatic interactions.

The physics is crucial here, but to simplify things, viruses tend to adhere to metal surfaces despite their inherent negative charge. The electrostatic spray system ensures that the entire surface is adequately covered with the disinfectant. The disinfectant then kills the pathogen.

Where to use electrostatic disinfectant sprayers

Electrostatic disinfectant sprayers are incredibly versatile. Their ability to reach the backs and undersides of objects makes them particularly suitable for indoor spaces with unique features. The speed with which an electrostatic disinfectant sprayer can cover thousands of feet of square footage also makes them well suited for large-scale indoor spaces.

Unlike conventional sprayers, however, charge matters with electrostatic disinfectant sprayers. Most electrostatic disinfectant sprayers apply a positive charge to the spray droplet because floors, walls, and furniture all carry a negative charge.

What to look for in an electrostatic disinfectant sprayer

First, it’s important to consider both components of an electrostatic disinfectant sprayer before purchasing one: the spray system itself and the disinfectant.

There are a number of electrostatic disinfectant sprayer models available. Additionally, the companies that produce them all provide clear recommendations on disinfectants that make it easy for consumers to choose the best sprayer-disinfectant combination for their needs.

Comparing different electrostatic disinfectant sprayers

The companies that produce the leading electrostatic disinfectant sprayers on the market include EMist, Ryobi, Victory, Protexus, Clorox, and Graco (which makes the SaniSpray HP 20). Handheld, backpack, and roller cart models are available.

All of these brands specialize in electrostatic spray systems designed to kill pathogens. The Victory Innovations Professional Cordless Backpack Sprayer, the EMist Epix360 sprayer, and the Protexus Handheld Sprayer are just a few examples of specific models.

Finding a good electrostatic disinfectant sprayer

There are several things to look for when considering an electrostatic disinfectant sprayer:

1. Product design. Handheld, backpack, and roller cart options are all available from several different brands.
2. Tank capacity. This can range from eight ounces for a handheld unit to several gallons.
3. Battery life. Lithium-ion batteries are the standard, and their battery life is impressive.
4. Weight. This is a consideration for handheld units (three to five pounds) and backpack units (ten pounds or more), especially if one operator is performing a large-scale disinfection.
5. Spray range. The spray from electrostatic sprayers generally extends two to five feet.
6. Droplet size. Most models allow the user to adjust the droplet size as needed, generally from 40 to 100 microns. The small droplet size increases deposition efficiency compared to conventional sprayers, which generate droplets in the 300 micron range.
7. Cost. Pricing varies significantly depending on the size of the sprayer.

Determining which electrostatic sprayer best suits your needs

The answer to this question depends in part on what kind of surface or facility you’re trying to disinfect. Handheld models are useful for smaller indoor spaces, such as cars, offices, and gyms. They also tend to be lightweight, which makes them convenient for the single user.

Backpack models have a large tank capacity and can cover significant square footage in a short period of time. Additionally, the favorable ergonomics of the backpack model limits operator fatigue. These sprayers perform well in schools, churches, fitness centers, and health-care facilities.

Another important consideration is that battery-powered electrostatic sprayers are cordless. This enhances maneuverability. Additionally, the lithium-ion batteries used in these spraying systems have an impressive battery life. They can support disinfecting sessions of up to eight hours.

Lastly, consumers should consider the disinfectant they intend to use. Dwell time is the amount of time a chemical agent needs to stay wet on a surface to justify its kill claim. Some electrostatic sprayers are better suited for specific disinfectants.

The future of disinfection and spray technology

The power of physics has spoken. Electrostatic disinfectant sprayers, with their versatility, speed, and efficiency, are the way of the future. If you’re interested in this technology, we’re here to support you in your learning process. Contact us at Spruce Industries to find out how we can help you implement electrostatic disinfectant sprayers into your cleaning protocol.