Opals are pretty.
Full stop
And they are incredibly rare and labor intensive to mine.
So why not just make them at home?
All it takes is seven or so months, a fume hood, some ethyl alcohol (purer is better), tetraethyl othosilicate, ammonium hydroxide, a stirrer, water bath, hot plate, resin, a vacuum chamber, and apparently infinite patience.
I looked into buying them, and even the synthetic ones aren't terribly cheap.
What's blue and smells like red paint?
Blue paint
You're welcome.
The material science in making blue colors - particularly when there aren't any blue pigments involved - is amazing. It's based primarily on interference with light reflecting off the surface and deeper layers within the wing scale. There's a great diagram of it at about 3:00 in the video.
It's similar to what happens on the rainbow surface of oil slicks on puddles...or on roast beef.
Even cooler, the butterfly wing scales also have nano-arrangements that also make them hydrophobic.
The video host is correct that the creation of the blues - and other similarly produced colors - is amazing.
It's pretty amazing that no vertebrates produce blue pigment and only a single butterfly actually does.
I'll be very happy when we don't have to take Covid tests anymore.
But I've taken a half dozen of these at home tests over the past year or so. I don't enjoy jabbing the long cotton swab into my nose - but the idea of then jabbing that swab into the back of my throat makes me want to gag.
There's a huge amount of serious science happening here that explains how the rapid covid tests work. Cool stuff happening there.
a small amount of solvent and ultra-fine silica nanoparticles onto the inside of bottles. Manufacturers already use solvents to change the texture of molded plastics, because they cause the surface of the plastic to soften a little. By mixing the silica and solvent, the researchers were able to soften the surface of the polypropylene just enough that when the plastic re-hardened, the silica would be embedded in the surface.
The structures are only a few micrometers—millionths of a meter—high, and covered in even smaller branchlike projections. They look like shaggy heart-shaped pillows, but they're hard as glass.
They don't cover the inside of the bottle completely, either, but instead are planted a few micrometers apart. The main branches of the "y" overhang the plastic surface at an angle less than 90 degrees—steep enough that water, oils and even surfactant can't physically sustain a droplet shape that would fall in between the branches and touch the plastic.
"You end up with air pockets underneath, and that's what gives you liquid repellency," Brown said.
Instead of spreading out on the surface, the soap droplets form beads and roll right off.
