The McK
They dumb.

Ageusiatic
I thought it was the mold they were pouring it into that popped from being heated up so rapidly.

Syd Midnight
Watch it like 20 times and you'll see that it happens on the left side of the right trough of the mold, maybe a tiny crack or a bubble in the metal, but the liquid metal definitely blows out from there.

Chibisuke
I think what happened is as the aluminum flowed to the left side, due to the large amount of surface tension, a bubble of air was able to get trapped beneath it when the flow hit the left side, and that bubble of air expanded rapidly so as to cause the explosion.

rapsnacks
Guys I'm pretty sure it was the mysterious incantation at the beginning of the video.

Enjoy
Bernoulli's principle at work once again. The air flow around the aluminum caused decreased pressure which compressed the aluminum to its incompressable state - resulting in an unsteady potential flow of H2O. To put it in laymens turns, this would be like peeing on a burning building: not going to solve the problem but may show up on Youtube.

fluffy
An air bubble in a crack seems like the most likely explanation, yeah. Especially if there was also moisture trapped along with it.

glasseye
Yep, tiniest bit of moisture = steam explosion = molten metal all over your face.

MrBuddy
glasseye got it right. They warned us in shop class and anytime I've seen molten metal demonstrations that if there's a tiny amount of any type of watery liquid around it will flash to steam and explode. First time I've seen it happen.

joelkazoo
*pfft*! You "scientists" done don't know nothin'!

JESUS did it!

SolRo
I imagine this is one of the reasons why every successful casting pour I've seen videos of involved heating the mold to a high temperature as well.

Also their mold is just sitting on top of the plastic* tabletop, I'm sure that wouldn't have melted as the mold heated up from thousand+ degree molten metal.

Syd Midnight
then spraying it on a red hot crucible that's burning the desk, and being surprised that the desk starts burning again

NineEleven
I'm sure you're just a glove-swatting machine who would only have taken .02 seconds to start swatting. Then your massive intelligence could have willed the fire extinguisher over .03 seconds later. So efficient.

zatojones
Or how to go to the academic advisor's office and change their major to business or some other stupid crap.

delicatessen
Even as business majors, these guys would find some way to be irrevocably burned by molten metal.

sosage
Most business majors deserve to be burned by molten metal, so it works out.

Dutch Oven Fresh Pie
These guys are in high school

(I looked at the tags)

kingarthur
As a business student, I say, "Heeeeeeeeeyyyyy....waitaminnit."

Sputum
What the hell kind of high school has the students working with molten metal?

dead_cat
What? Goddammit man, my high school fucking sucked.

Cube
EH, MARINA!

bopeton
http://www.poetv.com/video.php?vid=23191

Wombles
now, what was it you were doing?

mr666
Well, of course they lied. They were probably still scared shitless.

schwaeg87
"My eyes! The goggles do nothing!"

simon666
The guy with the goggles is fucking lucky he doesn't have a hole in face. "You had your face shiel.... Oh God."

Mister Shady
Fuck you, Mexican troll.

-1 for no permanent disfigurement via molten aluminum.

Chinballs
That's right, you tell him!

Get back under your bridge spanning the Rio Grande!