A violent method of opening champagne bottles helps explain how pyrex dishes are manufactured to be harder to break than regular glass, and more.
You've probably seen the little ceremonies that accompany opening up a bottle of champagne. Although it wastes nature's most precious gift, booze, and has the potential for wasting nature's second most precious gift, light fixtures, the ritual of popping the cork is one of life's minor joys. It's kind of fun, has a bit of danger, and gets a party started.
Many ask themselves: Is there a way of doing this that is more dangerous, wastes more alcohol, and turns the celebration from indulgent to obnoxious? It turns out there is. It even has its own term, sabrage. Sabrage involves taking a heavy knife and rapping it smartly against the lip of the champagne bottle. Instead of shattering the bottle, the lip flies cleanly off, cork and all, and the champagne is ready to drink.
All sabrage sites will give the same advice for knocking off the top of the bottle. Take off the foil of the champagne, and either loosen or remove the wire cage, so that it doesn't obstruct the base of the lip. Find the vertical seam of the bottle and follow it with the saber, quickly, as if peeling the outer layer of the bottle. Strike the point where the seam meets the lip of the bottle and enjoy seeing at least a glass of that champagne pour uselessly on the floor as the lip and the cork try their best to take someone's eye out. Probably a child's.
What's remarkable is not that a champagne bottle can be turned into a missile, it's that the lip comes away cleanly without shards flying everywhere. There's no explosion of glass because the combination of the lip and the seam make for a very weak point in a very strong bottle.
Glass is made up of molecules arranged in a crystalline structure, a rigid pattern iterated over and over again, like a kids' climbing structure. This structure is made when the molten silica is cooled and solidifies. The solidification process is fast, and often doesn't give every part of the structure a chance to get into place. As a result there are places where the regular pattern does not match up; invisible cracks in the glass. It is due to these cracks that much glass shatters so easily.
Some glass has to be much sturdier than the average water-bearing cup, and so manufacturers go through a process called annealing. Molten glass is held at just below solidification temperature so that all the minor tears and misalignments can sync up. The result is extremely crack-resistant glass like pyrex baking dishes or, to a lesser extent, champagne bottles.
Annealing can't get rid of all the little tears in the glass, though, especially at stress points. One of those points is the seam along the bottle. This is where two crystalline structures are squashed together, and it's unlikely that all the little pieces of the pattern match up. The second major stress point is at the lip of the bottle. The lip juts out at ninety degrees from the smooth side of the bottle, an extreme wrench in the pattern that causes a lot of small tears. Put the two together, and the result will be a linear network of tiny cracks with their weakest point right where the sword strikes. The strike will widen the cracks, which will join up with other tiny cracks, until the head of the bottle flies off cleanly.
The next step? Lightsabering champagne.