16 Things That Glow Under Black Light

This woman is wearing make-up that glows under a black light.

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There are a lot of everyday materials that fluoresce or glow when placed under a black light. A black light gives off highly energetic ultraviolet light. You can't see this part of the spectrum, which is how "black" lights got their name.

Fluorescent substances absorb the ultraviolet light and then re-emit it almost instantaneously. Some energy gets lost in the process, so the emitted light has a longer wavelength than the absorbed radiation, which makes this light visible and causes the material to appear to glow. Fluorescent molecules tend to have rigid structures and delocalized electrons.

Tonic Water Glows Under Black Light

quinine in tonic water
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The bitter flavoring of tonic water is due to the presence of quinine, which glows blue-white when placed under a black light. You'll see the glow in both regular and diet tonic water. Some bottles will grow more brightly than others, so if you're after the glow, take a pen-sized black light with you to the store.

Glowing Vitamins

Glowing pill
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Vitamin A and the B vitamins thiamine, niacin, and riboflavin are strongly fluorescent. Try crushing a vitamin B-12 tablet and dissolving it in vinegar. The solution will glow bright yellow under a black light.

Chlorophyll Glows Red Under Black Light

Chlorophyll from leaves glowing red under black light.
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Chlorophyll makes plants green, but it also fluoresces a blood red color. Grind some spinach or swiss chard in a small amount of alcohol (e.g., vodka or Everclear) and pour it through a coffee filter to get chlorophyll extract (you keep the part that stays on the filter, not the liquid). You can see the red glow using a black light or even a strong fluorescent bulb, such as an overhead projector lamp, which gives off ultraviolet light.

Scorpions Glow in Black Light

scorpion glowing under black light.
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Some species of scorpion glow when exposed to ultraviolet light. The emperor scorpion normally is dark brown or black, but it glows a bright blue-green when exposed to black light. The bark scorpion and European yellow-tailed scorpion also glow.

If you have a pet scorpion, you can check to see whether or not it glows using a black light, but don't keep it exposed to ultraviolet light for too long or it can suffer damage from the ultraviolet radiation.

People Have Stripes Under Ultraviolet Light

Close up of a tiger
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Humans have stripes, called Blaschko's Lines, that may be observed under a black or ultraviolet light. They don't glow, but instead become visible. 

Tooth Whiteners Glow Under Black Light

Person smiling under black light.
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Tooth whiteners, toothpaste, and some enamels contain compounds that glow blue to keep teeth from appearing yellow. Check your smile under black light and see the effect for yourself.

Antifreeze Glows in Black Light

Antifreeze being poured into a tank.

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Manufacturers purposely include fluorescent additives in antifreeze fluid. This makes it possible to use black lights to find antifreeze splashes to help investigators reconstruct automobile accident scenes. Antifreeze is so fluorescent, it glows even in sunlight!

Fluorescent Minerals and Gems Glow in Black Light

Close up of fluorescent willemite and calcite.

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Fluorescent rocks include fluorite, calcite, gypsum, ruby, talc, opal, agate, quartz, and amber. Minerals and gemstones are most commonly made fluorescent or phosphorescent due to the presence of impurities. The Hope Diamond, which is blue, phosphoresces red for several seconds after exposure to shortwave ultraviolet light.

Body Fluids Fluoresce Under Black Light

Urine in a cup held under ultraviolet light.
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Many body fluids contain fluorescent molecules. Forensic scientists use ultraviolet lights at crime scenes to find bloodurine, or semen.

Blood does not glow under a black light, but it reacts with a chemical that does fluoresce, so it can be detected after this reaction using ultraviolet light at a crime scene

Bank Notes Glow Under Black Light

Bank note under a black light.

 Bank notes, especially high-value bills, often glow under ultraviolet light. For example, modern US $20 bills contain a security strip near one edge that glows bright green under a black light.

Laundry Detergent and Other Cleaners Glow Under UV Light

Person with laundry detergent on their hands under blacklight.

Anne Helmenstine

Some of the whiteners in laundry detergent work by making your clothing a bit fluorescent. Even though clothing is rinsed after washing, residues on white clothing cause it to glow bluish-white under a black light. Blueing agents and softening agents often contain fluorescent dyes, too. The presence of these molecules sometimes causes white clothing to appear blue in photographs.

Banana Spots Glow Under Black Light

Bananas under both regular and black light.

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Banana spots glow under UV light. Shine a black light on a ripe banana with spots. Check out the area around the spots. 

Plastics Glow Under Black Light

Plastic disks glowing under black light.

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Many plastics glow under black light. Often, you can tell a plastic is likely to glow just by looking at it. For example, neon-colored acrylic may contain fluorescent molecules. Other types of plastic are less obvious. Plastic water bottles usually glow blue or violet under ultraviolet light.

White Paper Glows Under Black Light

Paper airplane leaning against wall under black light.

Eric Helmenstine

White paper is treated with fluorescent compounds to help it appear brighter and therefore whiter. Sometimes forgery of historical documents can be detected by placing them under a black light to see whether or not they fluoresce. White paper made post-1950 contains fluorescent chemicals while older paper doesn't.

Cosmetics May Glow Under Black Light

Person wearing makeup under black light.

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If you bought make-up or nail polish with the intention of getting it to glow under a black light, you knew what to expect. However, you might want to check your regular makeup too, or next time you pass a bright fluorescent light (emits UV) or black light, the effect might be more "rave party" than "office professional." Many cosmetics contain fluorescent molecules, mainly to brighten your complexion. Hint: The bars at many restaurants have black lights to make drinks look pretty. 

Fluorescent Plants and Animals

Close up of a group of jellyfish.

Nancy Ross / Getty Images

If you have a jellyfish handy, see what it looks like under a black light in a darkened room. Some of the proteins within a jellyfish are intensely fluorescent.

Corals and some fish may be fluorescent. Many fungi glow in the dark. Some flowers are "ultraviolet" colored, which you cannot ordinarily see, but may observe when you shine a black light on them.

Other Things That Glow Under Black Light

Martini glasses containing tonic water under blacklight.

AAR Studio / Getty Images

Many more items glow when exposed to black or ultraviolet light. Here is a partial list of other materials that glow:

  • Petroleum jelly, such as Vaseline, glows a bright blue color under a fluorescent light.
  • Uranium glass or vaseline glass
  • Rock salt
  • Fungus that causes Athlete's Foot
  • Turmeric (a spice)
  • Olive oil
  • Canola oil
  • Some postage stamps
  • Highlighter pens
  • Honey
  • Ketchup
  • Cotton balls
  • Pipe cleaners (chenille craft sticks)
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Helmenstine, Anne Marie, Ph.D. "16 Things That Glow Under Black Light." ThoughtCo, Oct. 12, 2022, thoughtco.com/what-glows-under-a-black-light-607615. Helmenstine, Anne Marie, Ph.D. (2022, October 12). 16 Things That Glow Under Black Light. Retrieved from https://www.thoughtco.com/what-glows-under-a-black-light-607615 Helmenstine, Anne Marie, Ph.D. "16 Things That Glow Under Black Light." ThoughtCo. https://www.thoughtco.com/what-glows-under-a-black-light-607615 (accessed March 24, 2023).