Uv tattoos are not glow-in-the-dark tattoos!

Hello, everyone. In this post I'll talk about differences between the main types of glowing tattoos, namely the Uv reactive tattoos (also called blacklight tattoos) and the so-called "glow in the dark tattoos". Blacklight tattoos (also known as UV tattoos) are often confused with the glow-in-the-dark tattoos and there are not few those who try to get a glow-in-the-dark tattoo and get instead a Uv reactive tattoo.

Blacklight tattoos

UV tattoos (blacklight tattoos, ultraviolet tattoos, uv-reactive tattoos, etc) are tattoos made with a special ink that is visible under ultraviolet light (blacklight). Contrary to popular belief, these tattoos DON'T CONTAIN either phospors or phosporus and they DON'T GLOW IN THE DARK. As their name implies, these tattoos don't glow by themselves, their luminosity is caused to REACT to the ultraviolet light (black light). They need a source of black light to glow; if you don't expose them at black light, they WON'T GLOW.

The ink used for the UV-tattoos contains fluorescent substances. Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. The emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation. The most striking examples of fluorescence occur when the absorbed radiation is in the ultraviolet region of the spectrum, and thus invisible to the human eye, and the emitted light is in the visible region (source: wikipedia).

Glow in the dark tattoos

Glow in the dark tattoos are made with phosphorescent ink; as any other phosphorescent substance, the phosphorescent ink needs to be charged with energy by exposure to light; the energy is "stored" for a (relatively) long time (depending on the phosphors used this time can vary from several minutes to several hours) and is slowly released in the form of light; due to this process of absorbing-storing-releasing of the energy, tattoos that contain phosphorescent ink glow in the dark. (read more about the phosphorescent tattoos in this post).

Related posts:
Uv-reactive tattoos and glow-in-the-dark tattoos for the Halloween-party. Are they a good idea or a very bad one? Glow-in-the-dark-tattoos: Phosphorescence / Persistent luminescence / Radioluminescence

Glow-in-the-dark-tattoos: Phosphorescence / Persistent luminescence / Radioluminescence

Hi, everyone. In this post I'll talk about an extremely popular misconception, which can be resumed into this single phrase: "Glow-in-the-dark tattoos that do not require a light source to glow because they contain phosphorus which can glow by itself". There is a lot of confusion here, so let's try to be clear step by step:

1. The ink that glow in the dark is (usually) phosphorescent ink, and it's different from the fluorescent ink (the Uv-reactive ink).

2. Phosphorescent materials/substances glow in the dark after the end of an excitation with ultra-violet light or visible light. In simple terms, phosphorescence is a process in which energy absorbed by a substance is released relatively slowly in the form of light. This is in some cases the mechanism used for "glow-in-the-dark" materials which are "charged" by exposure to light. Unlike the relatively swift reactions in fluorescence, such as those seen in a common fluorescent tube, phosphorescent materials "store" absorbed energy for a longer time, as the processes required to re-emit energy occur less often (source: wikipedia). So, since the phosphorescent materials need to be charged by expusure to light, it's obvious that if you keep your phosphorescent tattoo away from any source of light, it won't glow in the dark.

3. There are indeed some substances that glow without exposure to light, but these substance aren't either phosphorescent or fluorescent, they are radioluminescent substances (and radioactive).

4. Phosphorescent ink is made from phosphors such as silver-activated zinc sulfide or doped strontium aluminate, calcium sulfide, alkaline earth metal silicate, etc. These substances are called "phosphors". The chemical element Phosporus isn't phosphorescent; it emits light due to chemiluminescence, not phosphorescence (pretty confusing, isn't it?).

5. In phosphorescence, the lifetime of the emission of light lasts from several seconds to several minutes. If a material/substance can keep glowing for several hours, it's not correct to refer to that material as phosphorescent materials/substances. The phenomenon that occurs in this case is called Persistent luminescence and is commonly but incorrectly referred as phosphorescence. In order to make the phosphorescent ink/paint to glow several hours, various activators are added (e.g. the glow-in-the-dark cosmetic creams used for Halloween make-ups are made using the ZnS:Cu phosphor - Zinc sulfide activated with Copper). These activators are one of the reasons why you should avoid a permanent glow-in-the-dark tattoo.

6. As I've said before, there are, indeed, some types of substances that glow by themselves - the radioluminescent materials/substances. Radioluminescent paint contains a radioactive isotope (radionuclide) combined with a radioluminescent substance. The isotopes selected are typically strong emitters of fast electrons (beta radiation), preferred since this radiation will not penetrate an enclosure. Radioluminescent paints will glow without exposure to light until the radioactive isotope has decayed (or the phosphor degrades), which may be many years. They are therefore sometimes referred to as "self-luminous" (source - wikipedia). Tattoos made with radioluminescent ink can be very spectacular, but you don't want radioactive substances on or under your skin, don't you?

Related posts:
Uv-reactive tattoos and glow-in-the-dark tattoos for the Halloween-party. Are they a good idea or a very bad one?

Uv-reactive tattoos and glow-in-the-dark tattoos for the Halloween-party. Are they a good idea or a very bad one?

Lately I've seen more and more articles trat promotes the Uv-reactive tattoos and even the (in)famous "glow-in-the-dark" tattoos. It's true that these two kinds of tattoos are extremely spectacular, but before decide for one of them you should be aware about the possible side-effects of these peculiar tattoo-inks (on the other hand, there is no such thing as an 100% safe tattoo-ink; even the ink used for the temporary-tattoos presents risks for your health).

If the tattoo is meant to last only for one night you might consider getting a fluorescent-tattoo drawn with an alcohol-based ink, which is temporary, can be easily removed, it's cheap, it's pretty spectacular, it doesn't heart and carries fewer health risks than the fluorescent tattoos (not to mention the health risks carried by the phosphorescent tattoos).