Pressure and Heat; Shaken, Not Stirred

So my coworker and I went down to the cafe to grab some coffee. I usually take the Starbucks mug I got at a white elephant gift exchange last year. The thing is remarkably resilient - the seal is so secure, I can confidently flip it upside down while full of hot coffee. I've even dropped it before, and not a drop spilled.

The only problem with it is that it's really tall, and none of the coffee stirrers are long enough for it. I used to grab a plastic knife or a big drink straw to stir it, but lately to avoid the groups of people who congregate at the condiments, I just seal and shake my mug.

Now let's think about that for a second. The coffee is heated to 200 degrees or so, and I fill it nearly to the top (since I don't add cream). So there's a tiny bit of air left; and shaking it causes pressure to build up. Maybe I was extra vigorous today. You can guess what happened.

The seal on the mug popped open and a 10-foot jet of Starbucks' finest shot straight up to the ceiling, making contact. There were dozens of people in the cafe, and they were oooo-ing and aaahhh-ing like it was the Fourth of July.

Thankfully, the lid stayed securely screwed in, and no one was in the path of the stream or under it when it started raining coffee. The cafe staff were remarkably efficient at getting a "wet floor" sign up and taking care of the mess. My shirt did get nailed...thankfully I'm wearing my favorite black T-shirt underneath, so I don't need to walk around with a tell-tale brown stain.

Engineering types were looking up at the coffee spots in the lighting fixtures with looks of dazed wonder. "What happened? I've never seen coffee go that high before."

I felt like saying "Duh, it's coffee - it's not supposed to be airborne." But instead, I made a hasty embarassed exit.

Yup, that's me, Mr. Slick.