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UV Flashlights: Everything You Need To Know And Why

A scorpion glows green under a UV flashlight.

Key Takeaways:

  • UV flashlights are widely used in forensic science, counterfeit detection, fluid leak detection, and more.
  • When fluorescent materials are exposed to UV light, they will glow, which is a phenomenon called fluorescence
  • UV light is classified into three main types: UV-A, UV-B, and UV-C.
  • Most UV flashlights use a combination of UV-A and UV-B while blacklights only use UV-A

In the realm of illumination tools, flashlights are undoubtedly indispensable companions in various situations, ranging from outdoor adventures to everyday household tasks. Among the diverse array of flashlights available, one particular type stands out for its unique functionality and applications – the UV flashlight. In this post, we'll delve into what exactly a UV flashlight is, how it differs from a conventional flashlight, and the scenarios in which it proves invaluable.

Unveiling UV Flashlights

UV flashlights, also known as ultraviolet flashlights, emit ultraviolet (UV) light instead of the visible white light produced by conventional flashlights. Ultraviolet light is a form of electromagnetic radiation that exists outside the visible spectrum, meaning it's not visible to the human eye. It has a shorter wavelength than visible light but longer than X-rays.

What’s the difference between a UV light and a normal light?

UV light and regular visible light differ primarily in their wavelengths. UV light has a shorter wavelength, typically ranging from about 10 nanometers (nm) to 400 nm, compared to visible light, which ranges from about 400 nm to 700 nm. This difference in wavelength means that UV light is not visible to the human eye, while visible light is.

Three Types of UV Light

UV light is classified into three main types: UV-A, UV-B, and UV-C, each with different wavelengths and properties.

UV-A has the longest wavelength within the UV light family and is closest to visible light. Despite its relatively longer wavelengths, UV-A radiation still possesses significant energy. While UV-A is less harmful compared to UV-B and UV-C, it still can contribute to skin aging and certain types of skin damage. It is commonly utilized in tanning beds and certain medical treatments. While UV-A plays a role in inducing the production of vitamin D, a crucial vitamin, in the skin, over-tanning may cause skin damage or skin cancer 

In contrast, UV-B radiation has wavelengths that are longer than UV-A s but longer than UV-C. UV-B radiation harbors higher energy levels compared to UV-A but is less potent than UV-C. Despite its intermediary position in terms of energy levels, UV-B is responsible for most of the harmful effects of UV radiation on living organisms. Exposure to UV-B radiation can result in sunburn, skin aging, and an increased risk of skin cancer. It is partially absorbed by the Earth's ozone layer, which serves as a protective barrier against excessive UV-B exposure. This is why it is so important to protect the ozone layer so that UV-B radiation won’t penetrate through and harm humans, animals, and all the living organisms on the earth.

UV-C radiation, the most energetic and shortest-wavelength segment among the three types, exhibits the highest energy levels and poses the most significant threat to living organisms. Fortunately, UV-C radiation is effectively absorbed by the Earth's ozone layer and does not reach the Earth's surface in significant amounts under normal circumstances. On the other hand, UV-C radiation finds extensive use in sterilization applications due to its potent germicidal properties. Employed in water treatment, air purification, and disinfection of surfaces and medical equipment, UV-C radiation serves as a powerful tool in ensuring cleanliness and preventing the spread of pathogens in various settings.

Is Blacklight the same as UV light? 

Blacklight, often referred to as ultraviolet light in colloquial terms, specifically emits UV-A radiation. Black lights are designed to emit UV radiation while minimizing visible light, giving them a dim or "black" appearance when directly viewed. They are commonly used in entertainment settings such as clubs and parties, where they cause fluorescent and phosphorescent materials to glow brightly. Additionally, black lights find application in forensic investigations for detecting bodily fluids and other substances that fluoresce under UV light.

A black light that is attached to a wall.
A person stands next to a jellyfish tank that is dark and shining UV light on the jellyfish to make them glow.

The Magic of UV Light

A unique property of UV light that visible light does not have lies in its ability to interact with certain substances in a phenomenon known as fluorescence, as we mentioned when talking about blacklight. When exposed to UV light, certain compounds and substances absorb the UV radiation and subsequently emit light at longer wavelengths within the visible spectrum. This phenomenon then causes the substance to appear to glow or fluoresce when illuminated by UV light.

How do people use UV lights?

Forensic Investigations

One key application is the detection of bodily fluids and other trace evidence at crime scenes. Biological fluids such as blood, saliva, urine, and more fluoresce under UV light, emitting visible light at different wavelengths. This fluorescence allows forensic investigators to identify and document the presence of these substances even when they are not visible to the naked eye. UV light can also reveal latent fingerprints on various surfaces by enhancing the contrast between the fingerprint residues and the background material.

A person in scrubs uses UV light to identify something on the floor

Counterfeit Detection 

Official documents, currency, and identification cards often incorporate security features that fluoresce under UV light. UV flashlights are employed by professionals in banking, law enforcement, and retail sectors to verify the authenticity of these documents. UV flashlights help detect counterfeit items and prevent fraud by revealing hidden fluorescent elements. Similarly, many consumer products, including passports, driver's licenses, credit cards, and luxury goods, feature UV-reactive security marks or tags. UV flashlights are used by retailers and consumers to identify these markings, ensuring the authenticity of products and safeguarding against counterfeit merchandise.

A UV strip glows on a $20 bill under a UV light

Pet Stain Detection

Pet owners or cleaning professionals can easily locate urine stains and assess the extent of contamination thanks to UV light. This method helps ensure thorough cleaning and odor removal, as untreated urine stains can lead to persistent odors and potential health hazards. Moreover, UV light can aid in identifying areas that require targeted cleaning or treatment to prevent re-soiling and maintain a hygienic environment for both pets and humans.

Pet urine that is glowing under a UV light

Fluid Leak Detection

HVAC technicians use UV light to detect fluid leaks in HVAC systems by employing fluorescent dyes that are added to the system's refrigerant or lubricant. To detect a leak, technicians inject a small amount of UV fluorescent dye into the system. As the system operates and the fluid circulates, the dye will flow with the refrigerant or lubricant throughout the system. If there is a leak, the dye will escape along with the fluid and accumulate at the leak site. Once the dye has been introduced into the system, technicians use a UV lamp or flashlight to inspect various components of the HVAC system, including pipes, joints, fittings, and connections. When illuminated by the UV light, any leaked dye will fluoresce brightly, making it easy for technicians to identify the location of the leak.

Oil that is leaking from a machine glows under a UV light.

Mineral Hunting

By carefully observing the fluorescence patterns and colors, mineral hunters can distinguish different minerals and potentially discover valuable specimens. This method is beneficial in areas known for fluorescent mineral occurrences, such as certain geological formations or mining sites. Additionally, UV light can help differentiate between similar-looking minerals based on their fluorescence properties, aiding in mineral identification and classification.

A collection of rock under UV light and then normal light

Insect Spotting

UV light is commonly used in insect spotting and entomology for various purposes, including studying insect behavior, identifying species, and controlling insect populations. Insects, particularly certain species like scorpions, bees, and some types of beetles, have compounds in their exoskeletons or bodies that fluoresce under UV light. This fluorescence can range from green to blue to white, depending on the species and the compounds present. By using UV light sources, such as handheld UV flashlights or black lights, entomologists and insect enthusiasts can effectively spot and identify insects, especially in low-light conditions or dark environments. This method is particularly useful for nocturnal insects that are active during the night. 

In addition to identifying insects, UV light can also be used in pest control strategies. For example, some insect traps and pest control devices utilize UV light to attract and capture flying insects like mosquitoes, flies, and moths. The UV light attracts these insects, causing them to fly towards the light source and get trapped or killed by the trap mechanism.

A scorpion glowing green under a blacklight

So Why Should You Get A UV Flashlight?

Whether for personal use or professional purposes, investing in a UV flashlight equips individuals with a powerful tool for uncovering hidden revelations and addressing a wide range of needs effectively. It can inspect cleanliness and hygiene in bathrooms and kitchens by detecting unseen stains and residues that may not be visible under normal lighting. Additionally, UV flashlights can help identify areas of concern in hotel rooms, rental properties, or public spaces by revealing any biological contaminants or unsanitary conditions. Furthermore, UV flashlights are useful for checking the authenticity of identification cards, passports, and currency notes, especially while traveling or conducting financial transactions. Overall, having a UV flashlight as part of your everyday carry can provide peace of mind and assist in various situations where uncovering hidden substances or verifying authenticity is important.


In conclusion, UV flashlights offer a unique perspective by illuminating the unseen, revealing hidden substances and phenomena that evade detection under conventional lighting. Their specialized applications span various domains, including forensic science, counterfeit detection, fluid leak detection, pet stain removal, mineral hunting, and insect observation. Understanding the distinctions between UV flashlights and traditional flashlights equips individuals with the knowledge to leverage these tools effectively across diverse scenarios, unlocking a world of hidden revelations with the flick of a switch.


If you’re interested in getting your own UV flashlight, check out our available UV lights here!

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