Not all that glitters is polyethylene terephthalate · 10:56am Nov 13th, 2022
Now I just need to figure out how to control my alicorn magic without dumping several tonnes of microplastic pollution in a sensitive marine environment.
Glitter is clearly an essential element of life in Equestria. The crucial component in Izzy’s crafts; the indispensable ingredient in Mane Melody hoof polish. The manestream magic that keeps everypony’s sparkle shining bright.
It is just as essential to Hasbro toys, Christmas decorations, shimmering eyeshadow, unicorn snot, and all the other sparkly things that we will spend our money on during the festive season. Everyone loves glitter. Marketers are well aware that children will choose the glittery unicorn over the plain one. There is an evolutionary psychology theory that our attraction to shiny things comes from our biological need for fresh water.
The physics behind glitter is straightforward – you need lots of little pieces with smooth reflective surfaces to reflect light, such as a polymer film coated with a thin layer of aluminium or another metal. More interesting is de-luxe iridescent glitter, that sparkles like a rainbow by sending different colours in different directions. This is made from many layers of opaque plastic, each less than a micrometre thick. When the extra distance travelled by the ray reflecting off a lower layer equals the wavelength of light, constructive interfere will amplify that colour at that viewing angle, like a film of oil on a wet road or an old compact disk.
Glitter can be made from a lot of materials including crystals of mica, granular sugar, beetle wings. However the standard material for modern industrial glitter is metalized polyethylene terephthalate (PET). There is a lovely article in the New York Times from 2018: What is Glitter, in which Caity Weaver investigates the surprisingly secretive American glitter industry. Glitter has some applications you may not expect. It is used to prevent counterfeiting. Traces of glitter can be evidence in criminal investigations. According to Weaver, the FBI has a catalogue of glitter samples.
In my world of science communication, it is known that anything involving glue sticks and glitter is a good way to engage younger children. There are plenty of astro-craft projects where you make your own galaxy and learn about the spiral structure of the Milky Way, and how the shape of the galaxies we see depends on their orientation. When I spoke with a colleague in the Galaxy Zoo team, their top tip was: make sure you use biodegradable glitter. Not just because of the environmental impact of the glittery galaxy models ending up in landfill sites, but because if you don’t, you will have it explained to you by an eco-conscious ten-year-old, and that will distract attention away from what you wanted to tell them.
They are not wrong. These tiny particles of microplastic glitter can take thousands of years to decompose. They get in the oceans and are eaten by marine creatures from plankton to whales. This story is widely reported, especially in science magazines aimed at children. When you dig into the details, the full impact on the ecosystem is not yet clear, but it’s fair to say that all those plastic particles floating on the surface, and accumulating in deep sediment, can’t be good. Fortunately, there are alternatives, such as cellulose nanocrystals (‘vegan glitter’) under development at the University of Cambridge. These promise to sparkle just as well without contaminating our sushi.
I was just thinking about that particular plastic in pony toys too. Really gets everywhere, don't it?
I choose to believe that alicorn magic is biodegradable, thanks to that Earth pony component.
Low density polyethylene, otherwise known as Apple Sweat.
If Bakelite microplastic particless are discovered from before the Industrial age, could that be used to trace where aincient ants got peed on by animals? Urea formaldehyde?
My favourite use for metalised micron thick plastic is press logic cofing holgrams into it and use it as a solar sail concentrator reflector for an ion or even plasma drive wher the drive is used for high power communication transmission as well. Intresting how you can find ground side microwave thrusters and laser propelled crewed spacecraft, but so far I havent seen any self propelled microwave powered systems that can drift for a long time.
Another variation for glitter, used for a similar reason to the noise induving water glint reflections, is strips of thin aluminium foil called Window, used to create fake radar returns. Such as in the massive non existing virtual invasion flotilla during the D-Day landings, created by 617 Squadron Dambusters due to their experience in precision steady flying and timing.
And Chaff. which is getting ever harder to block Ultra Wide Band radar detectiona nd cable broadband polyphase and multispectral recievers and decode? Anti flicker filters? There was a processing chip released about a decade ago that could do the processing automatically but it seems to have dissapeared.
Strangely, the multilayer design of glitter seems to be alot cheaper t make, or at least sell, than if the thin layers are made of silicon and Indium tin Oxide etc Kodak colour film style multilayer solar PV, given the same tech and processing accuracies are needed for visible light interference?
"Dirt is just unprocessed glitter." -Izzy Moonbow.
I learn something new every time I read one of your blog posts :-)
The hypothesis that we like shiny wet water makes sense. Another interesting hypothesis is that we are so prone to acne because popping whiteheads and expressing blackheads replaced grooming for parasites socially, after we became less hairy. Given that acne-extration videos routinely receive millions of hits, this seems plausible (people watch them and go into trances).