how do you work science?!

December 1, 2012 6:38 AM

Can someone explain with SCIENCE, how this glass jar just exploded in my bathroom while I was taking a shower, and ended up almost entirely on the other side of the shower curtain?

I have/had an Ikea glass jar in my bathroom, that was holding some decorative fake mossy green balls. It was sitting on a glass wall shelf. The lid sat lightly on the top - it was not air tight. Bathroom does get mildly steamy - I live alone in a studio condo, so I usually shower with the doors open and the fan on, so it doesn't really get very steamy.

I hear some cracking, exploding, and suddenly there's glass under my feet while I'm taking a shower. My shower curtain was closed. On the side closest to the plumbing, the shower curtain wraps around in the tub, so there's not much room there. I leave it open a few inches on the far side.

There is about 2-3" between the shower curtain and the ceiling. Somehow, this jar flew and crashed on the far side of the tub. There is zero glass on the floor or on the bathmats. But somehow, the lid ended up a few feet away.

I assume steam broke the glass, but how the hell did it end up broken entirely in the tub?! Did my glass jar fly? Is a ghost trying to kill me? What the hell just happened?!

Pictures of the crime scene here (note the shiny parts on the floor are not glass - they're water drippings from me running to escape)

posted by raztaj to Science & Nature (28 answers total)

Your pic is set to private.
posted by batmonkey at 6:42 AM on December 1, 2012

Response by poster: batmonkey: fixed, thank you. pictures are here
posted by raztaj at 6:44 AM on December 1, 2012

Was it sitting on that glass shelf near the tub? Is it possible the shelf shifted, there was a tremor, or was otherwise disturbed enough to send the jar sliding off the shelf? That trajectory could have easily taken the jar past the curtain and into the bathtub. You might have missed the curtain moving if it passed near the wall.
posted by ninjakins at 6:47 AM on December 1, 2012

I'll guess that manufacturing stresses in the thick glass base finally let go basically at random and it exploded, which would propel it upwards away from the shelf it was sitting on. Chance took it towards the shower stall and it bounced off the ceiling and towards you.
posted by seanmpuckett at 6:48 AM on December 1, 2012 [1 favorite]

I don't know what the "fake mossy green balls" were made of, but could they have absorbed moisture from this and previous showers, expanded, and cracked the jar?
posted by scruss at 6:48 AM on December 1, 2012

Response by poster: The jar had to have gone around the shower curtain, on the side away from the plumbing/wall. That's where it shattered, and all the glass was. I was standing by the shower head on the side closest to the shelf. There is absolutely zero anywhere else in the bathroom, except the other side of the tub - not even any on the wall of the tub. I don't see any marks on the wall, ceiling, door, or bi-fold closet doors where it could have flew, hit, and bounced off from. It's like it flew 4 feet out, and then took an immediate hard left.

The mossy balls are foam at their core - it's possible they could have contributed to the jar cracking (I cleaned the shelf of dust 2 days ago - didn't notice any cracking), but doesn't explain the candy cane turn it took.
posted by raztaj at 7:01 AM on December 1, 2012

I live in a studio apartment too, and I often find that the acoustics of the place can cause some really weird perceptions (e.g., it sounds like my cell phone is on the opposite side of the room when it buzzes). I think you should really suspect what you think happened since running water + shower curtain + tightly enclosed space is going to make your perception at least suspect. You weren't expecting it either, so it's not like you were prepared to take into account everything that was happening.

What I think happened is the jar fell from the shelf, and lodged itself between the shower curtain and tub. This impact caused the jar to roll sideways toward the end of the tub, and the shock of the hot water caused the glass to expand too quickly and explode.

Another possibility is the jar began to crack due to the steam and manufacturing stress (as someone above mentioned). This is what you heard in the shower. This caused the jar to fall sideways into the tub, and then shower curtain/gravity/heat did the rest to make it end up at the far end of the tub.

I just find it extremely unlikely that the jar would fly 4 feet around the curtain to the end of the tub. I'm inclined to doubt what you think happened (no offense) due to the perception issues I mentioned above.
posted by uncannyslacks at 7:15 AM on December 1, 2012 [2 favorites]

It propelled away from the wall at an angle toward the curtain and blasted into the back of your shower because....ghosts, is my guess. Or perhaps those moss balls were breaking down and generating their own heat in the process, possibly filling the container with a gas. Your shower heated it up and it reached some state of energy transference. The energy couldn't be absorbed by the wall so BLAMMO!

It's very weird.
posted by amanda at 7:16 AM on December 1, 2012

Also, if there is NO glass or debris on the other side of the curtain, I think we can rule out that somehow the jar propelled itself to the far end of the tub. This would require an explosion of sorts, and there's just no evidence that anything exploded out there.

And yes, I agree, this is totally weird.
posted by uncannyslacks at 7:20 AM on December 1, 2012

Response by poster: What I think happened is the jar fell from the shelf, and lodged itself between the shower curtain and tub

Unless it wedged itself between the curtain and the liner, I don't know how this could have happened. In a rush to get out of all the glass, I pulled the curtain inwards - but I always keep the white cloth curtain on the outside of the tub - while the liner is on the inside.

I am spooked!
posted by raztaj at 7:58 AM on December 1, 2012

It fell off the shelf, hit the inside edge of the tub, shattered, and slid between the tub and the shower curtain down to your feet and scattering the pieces within the tub. The curtain is not a wall; it would provide zero resistance to a falling glass jar and the resulting debris. I don't think you have evidence of where it shattered; all you know is where the debris ended up. There's also no evidence here for the heat causing the glass to shatter. The water temperature coming out of your shower is, say, 110-120F on the high end. Any glass that can't stand that wouldn't survive a hot day in Arizona. I understand that a temperature differential is what would cause cracking, but I don't see anywhere to get a decent temperature gradient here.
posted by kiltedtaco at 8:11 AM on December 1, 2012 [3 favorites]

Maybe it fell off the shelf and hit the edge of the toilet tank hard enough to bounce towards the tub? It's round, and a hard round object striking a sharp edge (especially if it's spinning, as it probably might be) could glance off like a ricocheting bullet.

So yes, I'm suggesting that your toilet 'hit' the glass jar into the end of the bathtub, where it shattered.
posted by jrochest at 8:14 AM on December 1, 2012 [2 favorites]

Although the 'it fell into the bathtub, where the force of the water pushed it to the back wall' makes more sense.
posted by jrochest at 8:16 AM on December 1, 2012

Did you see whether the glass appeared from over the top of the curtain, or slid into the tub from under it or mid-height? Looking at the position of the toilet paper holder, I'm guessing that the jar fell off the shelf, bounced off the toilet paper -- which would have provided a cushiony trampoline effect -- and skidded along the rim of your tub along the curtain until falling in when it reached the curtain's edge. But that's just a guess. Personally, I think it was far more likely to be a ghost who dislikes all things Swedish.
posted by cuddles.mcsnuggy at 8:31 AM on December 1, 2012 [1 favorite]

I can't explain how it happened, but I can tell you that something similar happened to me. The day I knocked a canning jar full of homemade body scrub off the medicine chest shelf (parallel to the closed shower curtain and a few feet away), I watched it shatter on the counter on the way down, and glass went EVERYWHERE except into the sink and counter, where I expected it to go. There was glass on the floor beneath the sink cabinet, but also around the half-wall bend, out the door into the other room, and --- as I discovered the next day when I pulled open the curtain to run a bath --- yes, inside the bathtub despite being protected by two (one fabric, one vinyl) fully closed curtains.

And I'm absolutely sure they were fully closed because this happened minutes before my dinner guests were expected*. I always close the shower curtain fully (fabric on the outside, vinyl tucked in) before guests arrive because it saves me having to tidy up our chaotic bottles-and-brushes shower arrangement. I have no idea how glass got inside the tub, but I have no idea how glass got on the other side of a six-foot room partition, either. Breaking glass jumps around like wild.
posted by Elsa at 8:32 AM on December 1, 2012

Are you positive that the jar was on the shelf when you got into the shower?

Looking at your pics, I see that the shower head is one of those big, rain-like shower heads. Definitely large enough to hold that jar. Did you have friends over last night, or do you have a playful roommate? I could see someone thinking what a silly little prank it would be to place the jar on top of the shower head as a little tee-hee joke. Then it would be sitting on the shower head while the hot water was running through the shower, so it would be glass touching suddenly hot metal, which makes it a little more likely to crack and then fall to pieces in the shower.

If you aren't particularly tall, then the likelihood of you noticing it before you started the shower is a lot smaller.
posted by Brody's chum at 10:03 AM on December 1, 2012

Any cats in the household?
posted by a humble nudibranch at 10:04 AM on December 1, 2012

Response by poster: No cats. I'm positive that it was securely on the shelf - no people were over since I cleaned the shelf 2 days ago.
posted by raztaj at 10:10 AM on December 1, 2012

Where are the foam balls in all this? I didn't see them in your pictures...where did they end up?
posted by Pomo at 10:29 AM on December 1, 2012

Response by poster: pomo: foam moss balls are here mixed among the broken glass. They're dark green but look black in the pic.
posted by raztaj at 10:39 AM on December 1, 2012

Had you been in the shower since you dusted? Even if you had -- is it possible you put it on the rim of the bathtub to rest while you cleaned the shelf, continued cleaning other things, pulled the liner/curtain combo over it to create a tunnel, and then jostled the curtain a little as you were washing yourself so that in the end it fell over, rolled through the tunnel, fell again, and shattered, due to a combination of the cooler air inside the shower curtain tunnel making the glass a little cold and the heat of the water, plus the fragility of the glass?

I swore I put the Oreos in the cupboard the night before last, I swore it, but they were on the counter in the morning. I realized later that I put them in the cupboard after dessert and then thought, as a right-thinking person, that I should have two more, and at that point I moved it back out of the cupboard and left it on the counter. Point being -- I was totally convinced the Oreos shouldn't be there.
posted by A Terrible Llama at 11:21 AM on December 1, 2012

Hmm, I think what must have happened is that the jar fell off the shelf, didn't break initially, was bounced off toilet top/roll holder/ something???, hard enough to dislodge the lid and hit your outer shower curtain. It had enough momentum to slide/roll along that outer curtain to the gap at the far end, where it fell in your shower and broke. If it had broken outside your shower, the moss balls would have ended up in that place. It probably cracked at some point before it shattered.
posted by oneirodynia at 11:24 AM on December 1, 2012

... as to why it fell off the shelf, I've seen glasses that have water under them start to slide on slick tables. It may have been that your newly cleaned glass shelf was extra slick and condensation somehow got between shelf and jar. Perhaps the jar was in a slightly different spot, and it was able to travel to the edge of the glass shelf. I wonder if you peered closely at the shelf if any water marks would show the path of travel.
posted by oneirodynia at 11:28 AM on December 1, 2012 [4 favorites]

Also: check the lid for any dents, scrapes, or scratches. If it slid off the shelf and initially fell on the lid, it might more easily bounce into your shower. If you were me, think I would find a softball and practice rolling it off the shelf, just for fun. :)
posted by oneirodynia at 11:53 AM on December 1, 2012

That's similar to what I suspect could have caused the fall. Say you wipe down the glass, then replace the jar. You may have caused a vapor lock surrounding the entire bottom of the jar. When the shower steam entered the bathroom, the heat differential between the bathroom and the air in the gap under the jar (presuming there was one) could have compressed the glass shelf ever so slightly that it created a convex surface, off of which the jar could slide on a bed of moisture trapped under its own edge by surface tension. This would have then propelled the jar all the way off the shelf into the shower area, where it then burst on hitting the side of the tub.

Or poltergeists.

Anyway, do you have a bubble level? Do make sure that shelf is in fact level enough for the stuff you're putting on it.
posted by dhartung at 11:57 AM on December 1, 2012

This totally happened to me in 1982 when I was living on Wesr Peachtree Steet in Atlanta, Georgia. I was sitting there with Monica and Rosina and some other people, drinking, when suddenly a glass on the shelf exploded into pieces.

Freaky.

So we are students at Georgia Tech so I ask my professor the next day and he says "vibrations". Drinking glasses are tempered which means that they are cooled rapidly on the surface in order to create tensions in the crystalline structure of the glass. When the surface cools more rapidly than the core, it is like having bricks laid imperfectly. The result is that the glass is very hard and resistant to breaking, but when it does break it breaka into a million pieces - which is the result of releasing all of that stored tension.

Tempered glass has a lot of imperfections and if in the presence of loud noises and vibrations, it is not uncommon that these vibrations cause the glass to give and KABLOOM.
posted by three blind mice at 1:33 PM on December 1, 2012 [2 favorites]

Steam gets under the jar and around it as it's sitting on the shelf. The shelf is under a slight angle and not perfectly level. That causes the jar to slide from the glass shelf. The jar slides off, falls down and bounces up from the closed toilet seat and the small upward bump it gets is enough for it to hit the further edge of the bathtub (toward the end of the bathtub), shatters against the inside of the bathtub and glass is all contained inside the bathtub, held in by the walls around the bathtub and the curtain. If the toilet seat was not closed, maybe the jar bounce from the top of the open lids as they stood upright - alternatively, the jar fell on the edge of the open toilet seat, but that's less likely. The key to the bounce is that the toilet seat can flex slightly, thus providing enough bounce rather than immediate shatter which might happen if the glass jar itself has zero flex and the ceramic edge of the toilet itself has zero flex (although if the jar fell on its lid maybe there's just enough flex in the metal lid that it could provide a bounce!)

To check if this could happen, get a level and check to see if the glass shelf is perfectly parallel to the floor. If it instead inclines away from the wall and down toward the toilet, then anything on it, especially a glass jar could slide down when steam forms a glide path under the glass. If however the level is such that the shelf is angled up preventing such sliding off, this hypothesis will be null and void.
posted by VikingSword at 1:44 PM on December 1, 2012 [1 favorite]

Not really a direct answer but a (possibly) related anecdote that might add to the mystery-solving:
When I was in college, glasses would break in weird ways all the time. Someone would pick up a glass they were drinking from and it would shatter in their hands! We'd hear them shatter in the cabinets! Creepy! One of my roommates was dating a guy who was studying material science engineering, and he took some of our glasses down to the lab. Turns out, there were zillions of tiny tiny fractures. He hypothesized a too-hot dishwasher. We (somehow-- I don't remember) addressed the issue and never had a problem again with replacement glasses.

So... something something your shower something something steam something something too hot?
posted by lalalana at 10:09 AM on December 3, 2012