How does glow in the dark paint work?
Glow in the dark paint is an interesting product with many practical applications. But how does it work? There are two main types of glow in the dark paint: Fluorescent paint and Phosphorescent paint. This blog post will discuss the physics behind glow in the dark paint and how it creates its eerie effect.
All glow in the dark paints is luminous paint.
Luminous paint is any paint that absorbs energy from a light source (such as the sun or a lamp) and then slowly releases that energy over time. The paint will emit a faint glow when there is no light available.
There are three types of luminous paints:
- Phosphorescent paint
- Fluorescent paint
- Radioluminescent paint
Each type has its unique properties.
How does Phosphorescent Paint (AKA glow-in-the-dark paint) Work?
Phosphorescent paint is similar to fluorescent paint but contains phosphors instead of fluorescent agents. Phosphors are materials that absorb and store energy from an external light source, then release that energy in the form of light.
When the external light source is removed, the phosphors will continue to glow for some time. This is how phosphorescent paint appears to "glow" in the dark.
The duration of the glow will depend on the type of phosphor used in the paint and the amount of light the paint was exposed to. Some phosphors can glow for hours after exposure to light, while others will only glow for a few minutes.
How does Blacklight Paint (Fluorescent paint) work?
To understand how blacklight paint works, it's vital first to understand what blacklights are and how they work. Blacklights are a type of ultraviolet light. Ultraviolet (UV) light is invisible to the human eye but has shorter wavelengths than visible light.
When UV light hits an object, it causes the object to fluoresce or emit visible light. This is how blacklight paint appears to "glow" in the dark. The visible light emitted by the paint is usually blue or purple.
How Radioluminescent paint works?
Radioluminescent paint is a self-luminous paint that contains a small amount of a radioactive isotope (radionuclide) mixed with a radioluminescent phosphor chemical.
The radioisotope decays with time, producing radiation particles that strike the phosphor molecules and cause them to emit visible light. Beta radiation is emitted by isotopes, which are typically strong emitters of beta radiation because this type of radiation cannot pass through a barrier.
Radioluminescent paints will glow in the dark only until the radioactive isotope has decayed (or the phosphor degrades).
Radioluminescent paint is less commonly used today because of the radioactive isotope, which can be harmful if ingested or inhaled.
Does glow in the dark paint work without being exposed to light?
Yes, phosphorescent paint does not need to be exposed to light before it will glow. However, the intensity of the glow will depend on the type of radionuclide used in the paint.
How do you "charge"/"active" glow in the dark paint?
Fluorescent and phosphorescent paints are charged by exposure to light. The brighter the light, the longer the paint will glow.
Radioluminescent paint is activated by radioactivity. The radioisotopes used in radioluminescent paint are typically short-lived, so the paint will only glow for a few years.
How long does glow in the dark paint last?
Fluorescent and phosphorescent paints will continue to glow until the phosphor molecules are exhausted. This usually takes a few years.
Radioluminescent paint will only glow for as long as the radioisotopes used in the paint remain radioactive.
So what is the difference between Phosphorescent Paint and Blacklight Paint?
The main difference between phosphorescent paint and blacklight paint is that phosphorescent paint needs to be exposed to light before it will glow, while blacklight paint will glow in the dark without being exposed to light before.
Phosphorescent paint contains phosphors, while blacklight paint contains fluorescing agents. Phosphors are materials that absorb and store energy from an external light source, then release that energy in the form of light.
Both types of paint will glow in the dark, but the duration of the glow will differ. Phosphorescent paint will only glow for a short period, while blacklight paint will continue to glow until the molecules of the fluorescing agent are exhausted.