Why is Pyrex exploding? | How To Cook That Ann Reardon

I've found myself watching a bunch of cooking/science videos lately. Dunno why, but I partially blame the YouTube algorithm for steering me via what they present to me.

That being said, I love that there is a good overlap between science and food videos. In the above one, Ann Reardon, an Aussie YouTuber who does a bunch of debunking videos for recipes that seem too easy to be real, looks at the differences between Pyrex and pyrex including whether that simple capital letter logo trick really works to distinguish the borosilicate from the tempered soda lime glass.

She says it's not quite that easy, though I've heard it is that easy.

Either way, be careful with your kitchen pyrex and drastic temperature changes, folks.

Glass bakeware that shatters (December 2010) | Consumer Reports

How have I missed posting this in the blog? I've been using this video for a couple of years to explain that pyrex =/= Pyrex.

I would explain, but honestly, the Consumer Reports host up there does a great job explaining that consumer pyrex isn't the same as lab Pyrex and hasn't been for decades.

Tl;dr - don't take your pyrex casserole dish from the freezer to the oven or from the oven to the countertop.

Tempering Process

I've had a few former students sell Cutco Knives. I did end up buying a couple of knives from the first student because I had pitty on his 'cutting the rope' demonstration. In the long run, I haven't been impressed with the knives.

That all being said, I do use this video in my class to show quenching and tempering. It's a great show of those techniques.

August 3, 2013 Stick Bomb Tutorial

Ok, this might be a bit of a stretch today but stick with me. (groan)

We study tempered glass in material science. We go through the process of tempering - molten glass directly into cool water. The outside hardens quickly, locking in its shape while the inside is still molten and expanded. As the interior cools then, it tries to shrink and can't. So the inside is in tension - pulling inward - while the outside is in compression - being pulled together tightly by the inside glass.

If you don't know what I'm talking about or need the most awesome tutorial and visual of that ever, check out Destin's Prince Rupert's Drop video at 3:25. Destin also mentions that the Prince Rupert's Drop stores mechanical strain energy.

And for some reason this year when teaching tempered glass, the idea of a stick bomb popped into my head. I remember making very basic versions - of these when I was a teenager, but I never made anything approaching the long chains that you can see in the video up above. I am pretty sure, however, that the stick bombs also store mechanical strain energy in their structures - just like tempered glass does.

And it's a heck of a lot easier to have the students make in class than tempered glass is.



Though you can have the students make Prince Rupert's Drops.

MAKING A BOWIE KNIFE WITH REAL ENGINEERING!!! PART 2 - WHY we heat treat steel!

Finally, the testing...

The first part of the video is more making a knife - grinding the blade, drilling to attach the handle.

Then, at 5:50, the actual materials testing comes in. Alec Steele takes a steel bar and heat treats it different ways (not on camera, sadly) and gives each piece a few solid wacks with a sledge hammer.

These two videos (Alec's and Real Engineering - whatever that guy's name is) really balance the two sides of material science. Alec shows a lot of a practical knowledge. Real Engineering shows a lot of academic knowledge. Together they're pretty awesome.

Oh, and the testing wraps up around 12:25. Then it's back to finishing off the handle of the Bowie knife.

Heat Treatment -The Science of Forging (feat. Alec Steele)

There is something weird happening with the Real Engineering guy's accent. I'm struggling to place it exactly. There's a sing-song lilt to it that's screaming, "Irish" to me. Then, at 1:50, there's a weird ll-th thing going on with the 'through the heat treatment process' phrase that makes me think he's almost got Welsh in there. His patreon page says Galway, Ireland, but I've not heard that ll-th thing anywhere but from Wales.

Can anybody definitely say where he's from?

I'm going to have to check out the testing video from Alec Steele (an aptronym). Maybe that'll be next week's post.

So much great metallurgical explanation here...BCC, FCC, ferrite vs austenite vs pearlite, phase diagrams, quenching vs tempering vs annealing (normalising - British spelling, natch).

What quenching and tempering does to SWORDS

Trigger warning: Aussie accent...keep hacky comedians and actors away lest they start doing the Philosophers song.

There's a whole bunch of high-quality explanation in this one...

• 1:19 - percentage breakdown of carbon in various steels (low carbon, medium carbon, high carbon)
• 1:49 - "When the iron is hot...reaches the austenite phase...lost magnetic interaction...body centered cubic or face centered..." Honestly, he screws up the crystals verbally (though the graphics are correct) but does nicely say that "there's more room in between the iron atoms when it's this hot which means carbon atoms can all fit around evenly wherever they want" and that "when iron is cool...they try and squeeze out the carbon in between these iron atoms" and shows ferrite in the graphic
• 2:56 - micrograph of ferrite and cementite as the carbon in squeezed out from between the iron atoms, making pearlite
• 4:16 - Say "crystals" not "structure", man...c'mon
• 4:44 - discussion of work hardening and how that's lost once the metal is reheated, "it loosens the insides. It basically gives the opportunity for the stresses to be released and moved around and become uniform...as soon as you heat it up, you're losing whatever benefits - but also detriments - you might've put into the steel"
• 8:16 - "When heated up to where austenite is formed in the steel, the carbon is not forced into these veins/pocket/lines...and if you were to cool it down rapidly, you can actually give those iron atoms not enough time to force [carbon] out into these more condensed pockets...and a different, amazing crystalline structure is formed within the steel called martensite"
• 9:40 - "[Martensite] can be very useful to swords because you want swords to have a very hard edge, but you don't want them to be too brittle"...Goldilocks of metals, eh
• 10:05 - how the Japanese solved the problem, great diagram of the anatomy of a samurai sword (ion core, pearlite jacket, martensite edge) created via clay control of cooling rate
• 11:50 - tempering makes its appearance...we've been waiting, Shad
• 12:30 - showing quench of a katana with differential cooling causing bending in both directions (flubbed vocals but corrected captions)
• 13:10 - "[tempering] releases stress between these dislocations creating a much greater level of ductility and flex in between the crystal structure that's being formed within it" - nice micrographs of martensite and tempered martensite
• 15:00 onward...what makes for a good sword, particularly its sharpness...not so much material science 

Brad Makes a Knife with Bob Kramer | It's Alive | Bon Appétit

I'm a fan of goofy Brad, the host of the video series, It's Alive. Mostly the show is about cooking in the realm of fermented foods (kombucha, beer, garlic honey, cultured butter, sauerkraut, etc), but this time Brad goes to a small-scale knife shop because, as he says at about 13:10, "this ain't necessarily alive, but it's got energy...watching [the knife-making process] from start to finish, if it don't make you feel alive, I can't help you.

There are a bunch of metal topics covered here...

• 0:45 - "make some steel from scratch"...they make their steel from powdered ingredients (carbon, iron, manganese) and then melt them together
• 1:30 - induction heat melting of the steel ingredients
• 2:20 (and again at 3:00) - forging...the take the fresh, steel 'biscuit', reheat it 
• 2:45 - heating the steel back up to the plastic state...they don't mention the phase transition from BCC to FCC, but they do explain that hot steel can change it shape more easily...and that they have to reheat the 'biscuit' because it's getting cold
• 3:30 - rolling mill...a small mill but still far larger than what we show in the summer workshop
• 4:15 - forge welding different steels together...they only refer to the steels as steel A and steel B...no mention of high- or low-carbon steels
• 4:40 - iron oxide...the captions explain that, "[t]hose dark flakes are iron oxide. High temperatures accelerate the oxidation process."
• 6:20 - "quench tank there, Vinnie"...Vinnie is the camera man for all the Bon Appétit videos...no explanation yet as to why you would quench something
• 6:58 - hardening the knife...molten salt bath for an oxygen-free atmosphere for heating..."dissolving the carbon into the iron" then capturing it during the quench...followed by a tempering bath to, "bring the knife to a working hardness, so it's not too hard...not too brittle"..."when it's hardened, it's under a lot of STRESS...we go in there (the tempering bath) and it just adds some heat, kind of massages it...makes the knife 'happy'...yeah, this is the 'martini' for the knife"...there's a decent graphic summary of this at 7:50
• 8:40 - acid etching the knife..."the acid eats these layers at a different rate...because we mixed in different things in the steel"
• 11:20 - nothing curricular, but watching Bob Kramer put a blade on the knife just by eye as stunning...I assume it took a few more passes than what the video shows, but he makes it look so casual and awesome...I'm amazed

Warnings

• 7:35 - mention of making the steel happy via a 'martini'
• 10:20 - there's a bleeped, "I always f*#^ that up"

Brad's a goof, but it's loads of fun to watch him make a knife.

Glass explosion at 343,000 FPS! - The Slow Mo Guys

38 degrees out in July in Texas? That doesn't seem all that hot to me.

Of course, I'm assuming that they're in Fahrenheit because I'm American. If the Slow Mo Guys are resolutely not going to use specific units, I'm going to assume whatever units I want.

This video, by the way, is brilliant.

The guys take kitchen-grade pyrex (really tempered soda lime glass not the lab-grade borosilicate glass) measuring cups and subject them to drastic thermal shock - propane torch then ice cold water. The real money shot happens at 5:38.

Then there's an outstanding comparison of the speed of glass shattering to human reaction time at 7:15. The glass shatters - spoiler alert - way faster than an eyelid can blink shut.

Then, at 8:30 we get an explanation of thermal shock and what's happening with the expansion/contraction dichotomy with the glass.

Hydraulic Press | Prince Rupert Drops | Remake | Safe Tails

When it comes to hydraulic press YouTube channels, I'm more of a Hydraulic Press Channel guy than I am a PressTube guy. I'm particularly fond of the destruction of a hockey puck and of the vicious clay creatures that are stopped from wanton murder at the end of each video.

But I am willing to watch the derivative PressTube when they come up with something creative to destroy. In today's video, the PressTube folks destroy a Prince Rupert drop...or two...or ten. And, in the process, they also make some pretty big dents in a chunk of lead.

Investigators: Boy, 9, injured after glass shower door shatters

That's pretty much what tempered glass is supposed to do right there.

Yes, there may be a quality control issue in that the tempering might be better or worse depending on the production mechanics and controls, but that view of shattering into multiple small pieces is what's supposed to happen with tempered glass.

Ideally, those pieces would be smaller than some of those we see in the video, but that's way better than what untempered glass would cause - a very few large, heavy, sharp glass pieces falling down on the showerers.

The glass has to go somewhere, folks.

Let's be careful out there.

(Source)

How to Escape from a Car Window (slow motion) - Smarter Every Day 144

I think I've run out of ways to say that Destin is awesome.

It's like he's put together a video to perfectly explain the differences between tempered glass (like in the side windows of a car) and annealed glass (like what's laminated on the windshield of a car).

And he does it all in super slow motion.

I wanna buy his shirt even though I'm a pudgy XL, and his website says his shirts run small. Hence the largest size available - the XL - still worries me.

How to make Prince Rupert's drops - glass that fractures at the speed of high explosives

NightHawkInFlight doesn't specify which type of glass he's using, but I'm pretty sure it's just soda lime glass (available from Flinn Scientific, at least that's our common source for the summer camps.)

The technique for making Prince Rupert's drops takes a little practice but really isn't all that tough to manage with a little trial and error.

Here's another POV - including a fair bit of the science and where Prince Rupert's drops would fit into a science curriculum.

Shattering the Shatterproof

That just seems wasteful, destroying a spark plug like that. I mean a spark plug for my car is a whole seven or eight or even nine dollars.

The tinting on the windows, though, that's pretty cool.

I dig the simplicity of the sharp points of the shattered ceramic of the spark plug breaking the heck out of the tempered glass. The use of the big, wide-headed, rubber hammer is hokey, though, because it's about as un-sharp and pointy as it could be. It's a bit of cheating there, and it doesn't really work as an initial hammering for me.

They sure don't make pyrex like they used to

We've been hearing for a few years that Pyrex isn't what it used to be, that the quality control from the overseas manufacturing might be a little less strict than that in typical American manufacturing.

And now we know all about it thanks to Theodore Gray's Gray Matter column, which he largely has turned into his two, thoroughly entertaining Mad Science books. I even really like the legal disclaimers from the books (which I sadly can't find online for the linking). Lots of good reading there - along with some pretty spectacular photos of chemical reactions.

How It's Made Hammers

"No one-hit wonder"...funny stuff here...

I love the simplicity - in general appearance, anyway - of forging...and the fire that flares from the oil quenching at 2:20...

Ok, in reality, these look like really nice hammers, especially the ones with the resin-dipped leather handles.

"They've really nailed it"...still funny...

Anybody know who writes these How It's Made scripts?

Nova: Secrets of the Samurai Sword

From tip to tail, this one's worth showing in full. I know I can't quite make it in one of our periods (48 minutes last year, no guess how long this year), but it would be well worth two days. Brilliant stuff combining art, science, history, so much. Wow.

New video posted as of 7/30/14 - All times should be modified by subtracting about 20 seconds. For example, 11:30 listed below is more like 11:10 in this video.

My highlights...

• 11:30 - switching from BCC to FCC iron, paralleling the iron wire demo and showing how steel forms from the iron
• 12:45 - Thoe Gray's tour of the periodic table (love his book, app, poster, all of it)
• 15:00 - Charpy hardness testing explanation - toughness vs hardness
• 22:00 - The breaking up of the furnace is just gorgeous to watch...brilliant and blinding and beautiful. Wow...
• 23:00-25:30 - Could be skipped if need be, compares Japanese samurai films to American westerns
• 31:10 - cold working, work hardening of copper and how that relates to crystal defects in the sword
• 33:30-36:00 - Also could be skipped as it doesn't cover any science, just showing us how impressive the swords and swordsmen are.
• 36:40 - Differences in types of steel - high- and low-carbon steel - and how they are combined to make a better sword
• 40:50 - Heat treating, quenching and what it does to high- and low-carbon steels
• 44:00 - Differential thermal expansion, like a bimetallic strip
• 45:30-47:00 - Skippable...how to use the sword properly in fighting

Man, great stuff.

Light bulb filament

This video, made to accompany an article on Wired magazine's website, absolutely blows me away. First off, the ease with which The Engineer Guy takes off the glass envelope of the light bulb at 0:45 is stunning. Can anybody recreate that with a pipe cutter? I've been trying for a couple of weeks with absolutely no luck.

At 0:58 then, the video does a great zoom in on the supercoiled tungsten filament and shows the original 20-inch filament coiled then coiled again.

The next part of the video - from 1:30 through 2:30 - explores the ductility of tungsten and the processes necessary to make it ductile. The six steps - at 2:00 - absolutely blow my mind. That anybody could ever figure those steps out is amazing.

And the video closes with explaining the need for the glass envelope and the gas within.

Great, great video!

Tempered Glass Breakage

I'm always impressed with the surprising strength of tempered glass - and the willingness of people on YouTube to do stupid things without gloves.

When we discuss the strength of tempered glass in our summer workshops, occasionally a camper will ask why we would use such glass as a cutting board. If a nick on the edge (or especially the corner) leads to spectacular failure, why would be take a knife and go at the surface of the glass?

Because this video. That's why.

Tempered Glass Tests

"Breaking stuff for the sake of curiosity makes me happy."

Yup...

I had a camper in Provo this past week offer up a 4'x8' sheet of tempered glass for us to break. Seems like he had three of the sheets unused in his living room, there from a previous owner. The camper decided better of the breaking, though, but did promise to film, post, and share the video if he ever got around to breaking the sheet himself at a later date.

In this video Jason Patric our host throws a baseball, hits a golf ball, and finally shoots a metal bb at the glass to finally break the sheet. At 3:40 then the video explains why the tempered glass is so strong. In the end the host takes a tiny hammer to the edge of the sheet.