The Science of UV Resin

What is UV resin?

UV Resin is a type of photoreactive plastic—but what does that mean?

Let’s start with what “plastic” is. There’s no one scientific definition, but in general, a plastic is any entirely or partially synthetic (human-made) material that has polymers as the main chemical building block when in a solid state. A polymer (“many parts” in Ancient Greek) is a special type of molecule made from a long chain of simpler repeating molecules called monomers (“one part”) and oligomers (“few parts”). Because of their chain-like shape, polymers can create materials that are both strong and flexible. That’s why plastic is so useful as a building material: it’s easier to shape than metal or wood, but still strong.Now let’s talk about what “photoreactive” means. In Ancient Greek, photo means “light,” so something which chemically reacts to light is photo-reactive. These materials often contain special molecules called photoinitiators, which are what starts (or “initiates”) the internal chemical reaction to light.

Putting all of that together, UV resin is a material made mostly of monomers and oligomers with some photoinitiators added in… or, in other words, a photoreactive plastic! When liquid resin is exposed to a particular type of light called “UV” or “ultraviolet,” the photoinitiators begin a reaction called polymerization (or curing), in which all the monomers and oligomers link up into polymers to make a permanent, solid object. This reaction takes roughly 1-10 minutes, depending on how much resin there is and how powerful the UV light source is.

What does UV mean?

UV radiation is a wavelength of light that human eyes can’t see. That’s why we call it “UV” or “ultraviolet,” meaning “beyond violet” in Latin: it’s a color past the end of the human-visible rainbow (red, orange, yellow, green, blue, indigo, and violet).

However, many other animals can see UV light, from bees to reindeer to owls and more, and even though human eyes can’t detect it, the rest of our body reacts strongly to UV radiation. For instance, the reason humans naturally wake up in the morning and go to bed at night is because the sun gives off UV light, and that activates all kinds of chemical reactions in our brains. Our skin is photoreactive to UV light, too; that’s why we get both tans and sunburns!