Flashlight Information Other Lighting Information

UV Flashlight – Black Light Flashlight – More Then Meets The Eye

I’m sure you have heard of the term UV light and/or black light before but what is it and what purpose does it serve? Well a UV flashlight or light and a Black Light Flashlight or light can be used in forensic science, money counterfeit detection and medicine to include a few. So keep reading and find out if a UV flashlight or a Blacklight flashlight is what you’re looking for??

UV Flashlight

What Is UV Light?

Ultraviolet (UV) is actually electromagnetic radiation, similar to that emitted by the Sun. Fact: only 10% of sunlight is actually UV radiation. UV light has a wavelength of between 10nm to 400nm; that is shorter than that of visible light, but longer than X-rays.

Black light is also known as UV-A light, Wood’s lamp or ultraviolet light and is a lamp that emits long-wave (UV-A) ultraviolet light. All of these lights work on the same principle and have very little visible light.

When a violet filter is included on the bulb or in a separate glass filter over the lamp, most of the visible light is blocked and only UV is allowed to filter through and the lamp will have a dim violet glow when lit. This type of lighting is called black light and will be designated as ‘BLB’, which stands for ‘black light blue’.

Lamps that do not have the filter have a blue color when operated and are identified with the ‘BL’ designation by the industry. These are used in lighting for insect traps.

Other than the Sun, UV light can be produced by electric arcs and specialized lights e.g. mercury-vapor lights, tanning lamps and black lights.

Uv Bug Zapper


What is a black light flashlight?

Black light flashlights produce a narrow spectral band of ultraviolet light which is just at the lower end of the spectrum of light visible to the human eye. The light it emits is not literally black, and even though the light appears weak, since the human eye cannot see most of it, it is actually quite a strong source of light.

All items that emit a bright glow when lit up by a UV or Black light flashlight actually contain phosphors. Phosphors are the name given to substances which can absorb energy and then emit it as a visible light, known as luminescence. There are natural occurring phosphors, e.g. found in our fingernails and teeth, or chemical phosphors such as those used in laundry detergents to assist making white clothes appear whiter.

Black Light Flashlight

Black lights have many practical uses and these include everything from entertainment, commercial, industrial, beauty and healthcare. When black lights are used in medicine, forensics and in some areas of science we often hear them referred to as a Wood’s lamp. This is because it is named after the inventor of the original Wood’s glass UV filter, Robert Williams Wood, an American physicist.

Medical Applications for black light and ultraviolet light

⦁ Dermatology – at a wavelength of 365nm the skin can be observed. The dermatologist can observe certain forms of fungal infections, which will fluoresce pink; bacterial infections, which will show up as coral red or yellow-green and certain acne causing bacteria which have an orange glow. Vitiligo, the condition associated with patchy loss of pigmentation, can also be detected and will appear as yellow-green or blue under the Wood’s lamp. Melanomas can also be detected like this.

⦁ Diagnostics – the ingestion of antifreeze can be picked up in the urine. Doctor’s are able to see if a patient has ethylene glycol poisoning due to the fact that its manufacturers commonly add fluorescein to it, which causes the patient’s urine to fluoresce under a black light. Porphyria can also be detected from the urine, which turns pink when illuminated.

⦁ Neonatal care – Known as the Bili light, with a range of 420-470nm, babies born with jaundice can be treated with phototherapy.


Safety of Using Black Light or UV Light

Black lights produce mostly long-wave UVA radiation, with low frequency and low energy and very low UVB radiation. Although UVA has been linked to the development of skin cancer in humans, it is still the safest of the three spectra of UV light. That is because UVA is low energy and does not cause sunburn, but it does cause damage to collagen fibers which then accelerates skin ageing and it also destroys vitamin A in the skin.

UVB and UVC directly cause DNA damage to the skin; while UVA is not as easily absorbed it can only cause problems with overexposure in situations like sun bed use. The retina of the eyes can also be damaged from long exposure, but the use of sunglasses with good quality UV protection is essential.

Black Light and UV Flashlight Uses

1. Counterfeit currency

The legal banknotes of many countries have fluorescent symbols on them that show up under black light. The rest of the paper used in printing money is of a different quality to commercially available papers. That means that counterfeit money will fluoresce all over under black light, whereas real currency will only fluoresce on where the specific symbols are.

$20 under UV Examination for Counterfit

2. Authenticate other documents

The identification cards, passports, driver’s licenses and other official documentation of some countries are produced with the same principles as those for counterfeit money and can be verified with the use of a black light flashlight.

3. Biological Stains

The applications here are very useful. Pet owners can often smell urine, vomit or feces from their pets, but cannot find them once they have dried on carpeting or furniture. A black light flashlight will quickly help solve the problem. One just needs to turn off the lights and turn on the flashlight, and the stains will glow until completely cleaned.

Detectives and policemen are finding black light flashlights very useful at crime scenes where they can pick up traces of various bodily fluids and crime scene tampering. The flashlights can also detect certain types of drugs. LSD fluoresces under black light.

4. Inspection for bed bugs

Bed bugs can spread disease and we need to regularly inspect our mattresses at home and when visiting hotel rooms to ensure that there is no infestation. Bed bugs hate light and it is very difficult to find them in the daylight. Black light flashlights will not find the bed bugs directly, but the bugs do leave a trail, which the light will pick up.

5. Hotel room inspections

When traveling we all fear coming across a hotel room that appears to be clean, but we can’t shake off the feeling, or the smell, that it actually is not what it appears to be.

The black light flashlight will help you to inspect the sheets and other bedding for stains that include urine, semen, saliva and beverage stains. It can also be used to check the shower, bathtub, sink and toilet for stains.

On arrival to any hotel room, all you have to do is draw the curtains and begin the inspection and if the cleanliness of the establishment is lacking call up for them to do the job properly.

6. Insect collectors

Photographers and collectors of insects and moths use various types of black light flashlights to attract the specimens at night.

7. Scorpion identification

For those of us living in areas with scorpions, we know that they are not easy to see at night, even with traditional flashlights. With UV flashlights and black light flashlights they are easy to spot.

Scorpion Under Black Lights

8. Geological inspections

Black light flashlights are very useful to budding geologists or professionals who like to explore the countryside and caves for interesting mineral formations.

9. Heating, ventilation and air conditioning repairs

Refrigeration and air conditioning systems can be difficult to maintain. Technicians find portable black light flashlights useful in detecting leaks within compressor and refrigerator pipes. They often inject fluorescent dye into the system which will then light up as it leaks from the pipes.

10. Construction sturdiness

Engineers working on metal structures apply fluorescent fluids to these and then inspect them with black light to ensure that there are no cracks or other weaknesses in them.

11. Entertainment venues and other security applications

When working in offices or living in spaces with other people there are often mix-ups with items such as pens, flashlights, clothing and other apparatus necessary for us to complete tasks or get about our daily lives. This can be prevented by using fluorescent marking pens to put our names on these. The invisible writing will only show up when lit under a black light.

Black light Clubbing

Many entertainment venues like clubs, theme parks and festivals often use a fluorescent rubber stamp on the wrist of attendees. This allows them to ensure that those who have paid can leave and re-enter while others do not get in without paying.

12. Inspecting old homes or used furniture

The purchase of older homes or used furniture can often be wrought with dangers of later finding things that are well hidden. Black light flashlights help detect stains on carpeting and furniture and detect old mold stains in bathrooms and kitchens.


UV and black light flashlights are practical to use and cover large areas, depending on the number of LED bulbs. Most are water and shock resistant and are economical to use, while also hardy against falls and bangs. When operating UV or black light flashlights they should not be looked at directly into the light and should not be shone into the eyes of others.

I will be updated this post with recommended products shortly so please bookmark it if needed and check back shortly.

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