What broke this mug?


Aaaarh. The bottom fell out of my Scienceblogs coffee mug today! Don't fear, ya' scurvies. No one was hurt. For those so inclined, I provide a photo of the fracture and a brief analysis of the structural failure. You know, just for kicks. The details will of course be accompanied by fond reminiscence.

This was always a nice coffee mug because the handle stayed cool with hot liquids, even after it went through the microwave, which is something you can't say about every mug. Other favorite mugs from far away and special places like the Eiffel Tower in Paris and Burg Eltz in Germany can only be used for moderate temperature liquids and dainty teas. This mug was a workhorse, though. The clear glass lets you watch the milk swirl in three dimensions. Very nice for caffeine fueled ruminations on stratified downwelling flows in a rotating frame of reference.

Has this happened to anyone else? The fracture, I mean. Here's what I make of it. If you are a Scienceblogs coffee mug owner, you might notice a ventral seam running through the base and handle of the mug, and up the other side. This is not where the fracture occurred. The fracture ran up one side, but I presume the break occurred at the base, in the middle of an acute fracture I can see running at a ~20 degree angle to the seam. The seam is the stronger part of the mug.

Solids fail through the propagation of cracks, whose speed is controlled by instabilities at the smallest scales, according to the technical (but handy) website "How Things Break". By this logic, the heat from my wife's boiling hot dainty tea water would have forced expansion of the glass material, and the fracture would propagate outwards from a small instability like a bubble or a hairline crack. Make sense to you?

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It sounds plausible. This being from me, a first year science student, with only experience in having some glasses just randomly shatter with the addition of hot liquids.

Now you have me fearing for my own scienceblogs mug. I won one, and it's become my favorite over the "mug big enough to stick my head in," which in my view, is a proper size for a mug, really.

R.I.P poor science mug.

Blame temperature difference. I once lost a full pint of cold beer, because the bartender had poured it in a hot glass, straight out of the dishwasher. At my first sip the bottom dropped off spilling the beer all over the desk, and leaving me with an empty glass tube in my hand.

By Lassi Hippeläinen (not verified) on 30 Jan 2008 #permalink

Tragic loss of beer! Ouch. Temperature difference could be it. It was chilly this morning.

IT looks like the kind of break you get when you pour cold water into a hot glass coffeepot. I'd go with temperature differential.

I have two such mugs intact despite 6 months of cocoa, tea, and dish-washing. I can spare the spare. When you come back to NC to visit, it's here...

Perhaps the coffee was just too strong? ;)

What a sweetheart. Thanks, Sheril.
See you on 9th Street maybe. I'm lobbying for a replacement.

By Peter Etnoyer (not verified) on 31 Jan 2008 #permalink

Same thing happened to one of my two Sb mugs. I had warmed in the warming cupboard of my kitchen's wood cokestove, then poured cold milk into it, in anticipation a nice cuppa tea. Fractured upon introduction of the milk.

Lesson learned.

Peter, there isn't anything you'd like to share with us? No "uncanny" abilities that have come to light after puberty?

Ah, yes, Kevin, you've found me out. I've been revealed.
The mug was ruined by my super breath. The coffee was too hot, and when I blew on it, the glass simply shattered.

Hey, how did Sheril get two, anyway?