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UV/Blacklight Info

What is UV light?

The Latin term ultra means beyond, and the color violet has the shortest wavelengths of visible light. The wavelengths of Ultraviolet (UV) light are longer than X rays, but shorter then light. UV light is electromagnetic radiation.

What is Black light?

The term black light or UV light is used to a lamp or bulb that emits electromagnetic radiation that is in the ultraviolet range, and emits very little light that is visible to the human eye. Black light is UVA rays, which are the safest and least harmful of the three types of UV rays.
When used in the medical field, this is referred to as a Woods Lamp.


UVA = long wave UV (black light)
UVB = mid wave UV
UVC = short wave UV




Pest control

Scorpions glow when exposed to black light UV light. This occurs because fluorescent chemicals are present in the cuticle. When hunted at night, scorpions become unmistakably illuminated and their gathering places, points of entry and travel patterns can become known. When scorpions shed their outer shell, the short time until the new soft shell hardens is called Sclerotization. During this short process, black light UV light illuminating chemical is not present and they will not be illuminated as intensely as when their cuticle (shell) is hard.

Black light UV light is also used to attract insects to bug zapper traps. Many insects are drawn to the black light UV light, and then are killed with an electric shock when they come into contact with the device.

Rat and mice urine is also visible under a black light UV light, so professional exterminators often use them to locate hiding places and trails to resolve rodent problems.

For more information on scorpions, please refer to our About Scorpions page.

Security/ID and Document Verification

Most credit cards, drivers licenses and passports have watermarks that become visible under a black light UV light. Visa credit cards, when held under a black light UV light source, have a bird that is not otherwise visible.

Most countries issue Passports that have black light UV light sensitive inks and threads.

Some pepper sprays are manufactured with a UV Dye that is not easily washed off. This can assist police in the identification process later on.

Counterfeit Bill Identification

Using black light UV light flashlights is becoming increasingly more important to deter counterfeit efforts.

The vertical authenticity strip inserted into legitimate currency is visible under black light UV light. The unique paper that is used for legitimate currency does not fluoresce. Counterfeit bills are often printed on normal paper, containing phosphors that fluoresce. Consumers that would utilize counterfeit money often have altered IDs and other false identification forms that would be evident under black light UV light. Alterations become more apparent under black light UV light.

Mineral lighting and identification

Many minerals and gems display brilliant illumination when placed under black light UV light, allowing detailed analysis. While many are fluorescent, some are even phosphorescent. Phosphorescence is when the mineral actually continues to glow after the black light UV lightis removed.

Antique inspection

Black light UV light is used often to assist with inspection of antiques. Age can often be questioned if the paint glows. Older paints do not fluoresce, newer ones do. Newer paints contain phosphors, which glow.

Repairs are often more visible under black light UV light as well. If repairs have been made to a piece, the details become highly visible under the black light UV light. It assists in making a more accurate determination of the extent and quality of any repairs that have been made. Wear and damage that may be looked over at first glance are often caught under the light.

Art forgery/repair tests

Black light UV light is used for art inspection, very similar to how it is used to inspect antiques. Again, older paints do not fluoresce and newer paints do. This makes touch ups, damage and imperfections much more visible.

Club hand stamp screening

Re-entry stamps are used for clubs, parties and other events where entry is monitored. A stamp with ink that is visible under Black light UV light is used to stamp the hands of those permitted for entry or re-entry. Patrons are often irritated with stamps that leave ink that is visible and may stain. The UV visible ink is not visible until illuminated with a Black light UV light.

Machinery Leaks

Mechanics and A/C professionals can use a liquid ultraviolet dye that helps determine leaks. After injecting the dye into the system, a Black light UV light is used to make leaks visible.

Party fun for posters etc.

There are a variety of posters, paints and other items used to create a party like atmosphere. When exposed to black light UV light, they become very intense with color.

Pet and pest stains

Urine, feces and other body secretions are visible under black light UV light. Black light UV light is frequently used to locate pet urine odors where the exact source is unknown by homeowners and professionals.

Reading invisible fluorescent inks

Many inks are available that are visible only under black light UV light. Used for secret messages, this one is quite fun!

Crime scene investigation

Human urine, feces and semen are visible under black light UV light. In forensics, black light UV light is frequently used during an investigation.

Fingerprints are often examined under black light UV light after being dusted with a chemical that fluoresces well.

Hospitality industry sanitary checks

Since urine, semen, feces and saliva are visible under black light UV light; it is a good tool for sanity checks in hotels, public restrooms and such. Savvy travelers are known to carry a small black light UV light flashlight to determine the cleanliness of a hotel room prior to settling in. Some hotels are now using the black light UV light as a tool to ensure good sanitization standards.

Charge glow in the dark stars

Glow in the dark stars sure are fun, but take time to charge. Black light UV light charges the glow in the dark stars quickly and makes them glow super bright.

How was it discovered?

Johann Wilhelm, a physicist discovered that there were effects associated with UV light when he observed that silver salts darken when exposed to sunlight in 1801. That discovery headed off the research and discovery of UV rays, their effects, and what they are.

Human health-related effects of UV light

The sun emits three types of UV light. These are called UVA, UVB and UVC bands. 98.7% of the UV rays that are not filtered out by the ozone layer around the Earths atmosphere are UVA. UVB and UVC are actually responsible for generating the ozone layer. UVB actually initiates the skins natural production of vitamin D. Vitamin D deficiencies can cause many health problems, including cancer. Vitamin D supplements have become more prevalent to prevent deficiencies as we become increasingly aware of the skin damage (specifically cancer) that we know to be caused by UV exposure. UVA, UVB and UVC all destroy vitamin A in the skin.

While a lack of UVB exposure can cause a vitamin D deficiency, over exposure can be responsible for sunburn, skin cancer, and direct DNA damage. As the body recognizes, then repairs the damage, melanin production is increased and darkens the skin to what we call a tan. Overexposure to UVB rays can also cause damage to the eyes and the immune system. UVB light can cause photokeratitis, and can lead to cataracts, pterygium and pinguecula.

UVC is the most dangerous type of UV light. Almost all of the UVC rays are filtered or absorbed by the Earths atmosphere and do not reach the Earths surface.

Lesson to learn: Wear sunscreen and sunglasses!

What else does UV light do?

UV Degradation

UV light can damage pigments and dyes, changing their colors. It also can, over time, disintegrate sensitive polymers, like plastic. Depending on the exposure to sunlight and the intensity, some materials will fade, crack and begin to disintegrate.

Sunlight and fluorescent lighting can both be the cause of UV degradation.