Steve Mould - 2020-11-19
Get 4 months free when you buy a 2 year plan of NordVPN: https://nordvpn.com/steve and use promo code "steve" at checkout. PVC cement (it's technically not glue) spins in water. It might be because the solvent is being expelled onto the surface of the water creating jets the propel the blobs around. You can buy my books here: https://stevemould.com/books You can support me on Patreon here: https://www.patreon.com/stevemould just like these amazing people: Joseph Galliera Nathan Williams Matthew Cocke Glenn Watson Mark Brouwer Joseph Rocca Joël van der Loo Doug Peterson Yuh Saito Rashid Al M Paul Warelis Will Ackerly Marcel K Twitter: http://twitter.com/moulds Instagram: https://www.instagram.com/stevemouldscience/ Facebook: https://www.facebook.com/stevemouldscience/ Buy nerdy maths things: http://mathsgear.co.uk
The PVC cement is actually a suspension of low molecular weight PVC, these initiate furthrr polymerization on contact with water. This is how PVC is produced industrially. This process is extremely exothermic. I'm guessing the effect is caused by water forming PVC capsules, heating up the trapped solvent water mix until they break (as you speculated) and release a pressurised jet of hot liquid. Perhaps you could test with thermal imaging camera on cement in a small amount of water. Incidentally you weren't able to make your own cement because the PVC pipe is high molecular weight.
@tolkienfan1972 I know what a polymer is, I've just never seen something referred to by the molecular weight of its polymer before in that way if that makes sense. Like if you asked for the MW of cellulose I'd quote the monomer not some multiple of it. Does that make sense?
@Jay H makes perfect sense. I'm guessing the chain length gives the polymer varying material properties, so they specify it by molecular weight?
@tolkienfan1972 yeah that makes sense, I was just confused haha
Isn't it possible that the fairly high solubility of MEK in water could be causing a depression in the boiling point of the water locally and have a similar jetting effect?
Well, the production of pvc wster serves no other purpose than as a solvent and the process is initiated by a radical initiator, typically acylperoxides.
"It's not glue, and that's an important difference"
puts glue in title
@Rolf S That building stuff is concrete which has Portland cement in it
@skyboosm mathematics IS ;) singular
@skyboosm Sociology is that the new religion that college campuses promote?
@Sal Wolffs this is the real answer
“The most exciting phrase to hear in science, the one that heralds new discoveries, is not 'Eureka' but 'That's funny. '” – Isaac Asimov
@Satrio Esar This ought to be one of the best replies to the quote I've ever read. Thank you for the laugh.
gotta love asimov
@waffleboy159 great quote
I think my dissertation research direction was kicked off by an observation that had me staring at my computer and muttering "oh that's weird."
“I tried to make a solvent, but had mixed results”
Pretty good pun
Actually, not a solvent, a solution
Solvents can separate materials.
@Thomas Synths By mixing with the solvent ;)
@Nullpointer that was implied ;)
Why glue spins like crazy in water
“It’s not glue, and we don’t know.”
Thanks Steve!
lmao
"It not glue as we know it captain" - Spock.
I really want to quote Jesse Pinkman right now
"and he spent the rest of the day playing with drops of PVC cement in the puddle"
Meanwhile the water was shut off in his house and his wife was furious.. small price to pay in the name of science😋
Also his boss what do you mean you need more PVC cement and why is that job taking so long lol
Steve once abandoned groceries and his wife, to waste containers full of shampoo.
These people are a menace to society.
because its looks like free energy so he could have an idea
But you had fun!
"He spent the rest of the day adding drops of PVC cement to the puddle" I RESPECT THIS MAN
If he didn't, I wouldn't really trust him. Same with skipping stones on a frozen lake. If you hear that sound and not want to do it again and again, you are weird and not to be trusted.
I love how some of these videos don’t really give a satisfying answer. This is how real science works and it’s super interesting how much there still is to learn about the simplest things.
5:40 Wow, that dry ice floating around is mesmerizing. Very cool.
lol cool indeed
I worked at the Technorama for a while and yes, I loved watching those little pieces of ice! There's a lot of other great stuff there as well, including a fire tornado, levitating superconductors, a drawing pendulum, a cloud chamber and of course a chocolate workshop.
That happened with a dead insect recently with here.
I was cleaning the house, it fell on a puddle and started spinning like crazy. I checked closely to see if it was still moving, but other than that spinning, it was completely still, and it started instantly spinning again after I stopped examining it.
It's one of those insects that exhale a weird smell sometimes, so oils/aromatic components might have something to do with that effect, too.
@macronencer are you kidding? Many insects use smells as defense. The most known infamous is the nezara viridula.
@Lucas Rodmo No, I'm not kidding. Maybe it's because of where I live (UK). I don't remember ever smelling an insect :)
@macronencer find a shield bug (they are everywhere in UK) and annoy it a little bit - you'll get a smell a bit like laurel leaves or marzipan - some cyanidey compounds
@Pete Buckney I do come across those sometimes. Interesting! Thanks.
@macronencer stink bug?
Does the same effect happen was put the cement in different fluids that might not react with water?
Ooh! Good thought!
Also when you put a drop of water on the glue to see how the water reacts to being put in the glue!
I would definitely test oil....also changing temperature might be worth exploring
@A and alcohol
At first I thought it had something to do with Marangoni effect and the surface tension mismatch between the solvent and water, but the pepper really does reveal discrete jets and now I think the surface crust fracturing thing periodically releasing pulses of MEK as the droplet contracts probably is what's going on. Dye the cement with something like fluorescin and inspect the interaction with a UV lamp to maybe see what's going on in more detail...
Any dye that dissolves in that solvent will work if it can be mixed in uniformly.
https://pubs.acs.org/doi/10.1021/la301437f
I think the marangoni is right- here's a paper where they make a similar situation- plastic dissolved In solvent, added to water- moves in weird patterns.
Different plastic, and Ethanol instead of mek, but they seem fairly confident it's due to the marangoni effect, and they can even predict it so as to control the motion, so I'm inclined to believe them
@Ang Davies That looks just the same phenomenon
Now I’m just waiting for someone to do a master’s thesis on this
Now I'm just waiting for someone to patent a toy based on this principle
@columbus8myhw selling solvents to children won't get far
@xpqr12345 as long as we dont have to hear his voice
@Phil Boswell or using straw impractically extreme cases to 'debunk' things that only need practically feasible specifications
PVC cement is highly intelligent, but severely lacks arms to get out of a potential drowning situation.
I chuckled 😄
As a chemist in a adhesive maker who play with those cements everyday, I can tell that the main components of PVC cement is PVC, MEK, and cyclohexanone. (or tetrahydrofuran)
Since MEK , cyclohexanone and tetrahydrofuran are all partially or full water soluble, some solvent would dissolve into water and make PVC solidify into a film covering the blob.
And the osmosis difference building across the film pulls water into the blob and make the blob expand at the surface. (Therefore the films and wings form when wet blobs are dropped.)
When the blob is firmer and the film is fixed by rigidity and cannot expand, osmosis difference just pull solvent out into water instead and create a propelling stream.
Then with higher curvature of surface, the blob tail can gain more propulsion with more surface area, which makes blobs run, or spin if tail is warped.
Maybe try mixing some color into PVC cement and we can find more data.
Thanks for sharing this information! We need more to read this comment so Steve can read it! Liked
Perhaps plot motion vs time vs mass of drop to relate to reaction rate and then a scan through temps and digital video analysis a plot of motion would serve a bit like DSC to find peaks at specific temps
Does MEK in solution with water appreciably depress the boiling point of water?
Looks like microorganisms moving on the microscope
I got the same impression... I guess that part of microorganisms' "life" just responds to the same kind of chemistry effects...
cue the soundtrack by Andrew Huang
Glad to see I was not the only one seeing macroscopic scale amoeba like creatures in water peppered with other contaminants.
Ameoba, single celled life, waves a flagella.
that's eerie part
You can build a schliren imaging system to detect the solvent bursts.
Maybe even just food colouring in either the water or the cement would work?
@Tom Br Problem is you'd need something bonded to the solvent. As else it's measuring how well food colouring seeps out of the cement and might even cause undesired effects.
@TechyBen good point!
I wonder if you could get schlieren videography to work crossing a water boundary. In either direction. I feel like you'd have to be in the same material (air or water) as the light source and subject for this to work.
Might wanna get Smarter Every Day involved with this one!
Me: "I moved the light round a bit and I could see better."
Steve: "I used extreme lighting angles to take advantage of the differences in refractive index."
;P
I had to pause there and rewatch it about 10x's to get it. Lol
You have to stir the PVC in MEK at 50°C, then blend it to homogenize. Note: do not use your kitchen blender.
Very interesting video. Perhaps you may have given up on the surface tension theory a bit prematurely. I found that one droplet of liquid dish soap causes the PVC cement globs to stop moving immediately. This argues against the "driving force" arising entirely from the momentum of jets being expelled from inside the globs. Perhaps small amounts of solvent leach out (as you suggested) and cause fluctuations in the local surface tension. These fluctuations in surface tension may lead to the chaotic movement. The dish soap would lower the surface tension uniformly, thus abolishing any heterogeneity. We'll have to do more tinkering to sort this one out.
What a splendid theory! I’ll be sure to show theory to my father, he loves experiments like this.
I'm incredibly surprised (and pleasantly so) about how much a learned from this video. This was beyond fascinating and exactly why I've been an avid subscriber. Thank you so much for sharing!
It's like a pvc world with solvent "hot spots" that work their way up to the surface making volcanic eruptions of solvent into the water.
I thought of lava, too, as watching the blobs.
Outcome of the video: It's much harder selling a VPN since the Tom Scott video...
I like how people are able to reference Tom Scott everywhere on YouTube and people will understand
My friend sent me a list with usersnames and passwords of Nordvpn acounts, So this proves I can't trust them to keep my information safe
@Sagie Solomon proof or we can't take your word for this.
Benjamin Harvey Password managers do not store your passwords as salted hashes. Hash functions are, by definition, one-way functions. There's no way to retrieve the input from a hash. They actually use a symmetric cipher (e.g: Bitwarden uses AES-256 in CBC mode) to encrypt the stored passwords with a key derived from your master password (via a key derivation function such as PBKDF2).
@Benjamin Harvey good point, well made. Old UK duffer here :)
Intriguing, fascinating, beautifully filmed, and so clearly explained. As usual. Great video!
A bit of extra information: The key ingredient in most PVC cement is actually tetrahydrofuran, or THF. THF is an ether.
I'm guessing that's not as easily obtained as MEK, which can be procured from most hardware stores.
Steve, I am a commercial diver. I watched this video and when you talked about dry ice it brought up a memory... when groceries are sent offshore in the gulf of mexico, they are sent with dry ice. There was one occasion where I was in the water on a decompression and they threw the dry ice overboard. Dry ice sinks. But it sunk to a certain point and it stopped sinking. Then it seemed to hover mid water. I watched this phenomena for several minutes. I cannot remember my depth but I want to say it was shallower than 100', well within scuba range. It was awesome. I watched it come down off gassing the whole way and then just stop and off gassed until there was nothing left, and then another chunk was thrown overboard and did the same thing. I just found out about your channel and I am impressed. Maybe you can do something with this.
Probably the depth where the water is such high pressure That it has the Same weight as the dry ice. Water is liquid so ist gets compressed faster than a solid piece of ice
I have been observing this phenomenon in my work as a plumber for years. It's great to learn the answer is so complex. Please do a follow up with more results.
I like your "crust" theory. It's simple, elegant.
So amazing to find such interesting things in unexpected places. Thank you.
You are exceptionally good at explaining things. Thank you.
I'm always amazed with your videos, Steve for not only showing me something I have never seen before, but in demonstrating a theory on how that other thing might work, you show me something else I have never seen before to explain it. I loves it.
Great video - I'm just finishing my PhD about the behaviour of wood floating in hot fluidised particles. The wood emits jets of gas which interact with the fluid in a way not all together dissimilar to the dry ice on water demonstration. Indeed, I've used the dry ice/ water system was a quick way of explaining my research.
great video as always mr Mould! Whilst the pepper worked perfectly well, mica powder used in make up creates a rheoshopic fluid which would show all those cool water vortices really well!
Hi Steve, have you tried to dissolve other stuff in MEK to see if it behaves similarly? Or have you tried to have the PVC cement analysed, or bought different brands to test wether MEK is essential? Fascinating as always. Keep it going.
Steve from an alternate reality: "...And this is how soap-propelled yachts work in the grand ocean rallies."
Would give a whole new meaning to the words "Green Peace" ;)
This is one of the best videos you have put out Steve - thankyou this was excellent!
This makes me wonder if this odd spinning reaction could be used to generate a voltage and if it can, how long or useful would that voltage be? I suspect not very useful but might be possible
title: "Why Glue Spins Like Crazy In Water"
Steve: "PVC cement isn't actually glue"
smh...
@no-trick-pony_lockpicking he should have titled it "why does cement spin like crazy in water"
Cement is a type of glue I guess? There's a bonding happening
@Daniel Eh, if I hear 'cement' I'd be more inclined to think of something like Portland Cement instead of PVC cement. I don't think glue was the right word, but 'cement' on it's own would've prompted more confusion. I feel just saying 'pvc cement' would've been the best.
@Tim's Lab yeah it was more of a joke i thought it would have make a more clickbaity title
clickbait
Really cool. I think fluids are interesting in many ways. Looking forward to other videos on fluids! :)
Hey Steve!, I've noticed when using a garden hose you can cause it to hold itself up from the thrust it generates, BUT, when you submerge the end in to water it drops like it suddenly generates less thrust?? Any idea why? Could be an interesting video.
You need to hold the hose about 1m back from the end depending on water pressure for best results.
Cheers!
I remember an experiment from when I was a kid, where you would dip the end of a match in glue and it would move across a bowl of water when thrown into it.
We used "UHU Kraft Alleskleber" (from Germany) for that experiment. And that one contains dissolved polyurethane which solidifies when the solvent dries up.
The effect is similar so it probably is not related to the PVC but mostly the solvent.
Could you try mixing the PVC cement with food coloring or some kind of coloring to see more clearly where the blobs expel fluid?
I have a question: for how long will that material keep "Active" on the water ? is it the PVC cement reacting to the water or the water reacting to the PVC cement? I found this video utterly interesting. Thank you for sharing Steve :)
I like that you also showed your thinking, approach and how you tested it, complete with explanations.
=)
Steve, how long does the movement/reaction last? Can you set up a camera to record how long the movement lasts?
Does water temperature effect how the PVC cement acts? Also I’d be curious how it reacts in oil
Your inference ability is a great contribution to science, steve, and I believe your videos should have way more viewers than they get. Great job m8, keep it up.
Fascinating! As always wonderful job!
I'm glad you mentioned the dry ice. I grew up playing with dry ice a lot, and the movement of PVC cement in water reminded me a great deal of how dry ice chips would move on the surface of water.
How did you get dry ice?
Steve Mould - 2020-11-19
I never knew there was so much chemistry involved in plumbing. More research needed.
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Scott Jackwitz - 2021-01-18
I wonder what effect the temperature of the water would have on the cement
Ketansa Art - 2021-01-26
Its the solvant evaporating rapidly. If you want to see slow propelling, attach a small piece of camphor behind that boat that you used with soap.
Nona Suomi - 2021-04-26
@peepzorz Just stumbled across this video and yeah, seeing him just handling MEK-impregnated PVC with his bare hands definitely had me sucking my teeth. I keep some handy because it can act as a solvent for PLA (along with its isomer THF, which is actually the primary ingredient in most PVC cements), but really you shouldn't be messing with solvents without gloves at the very least.
David McElroy - 2021-06-16
Would be really interested to see the effect that the temperature of the water has on the speed of the movement. Also the fog on the co2 video is water condensation not co2 which is interesting.
Hallow Star - 2021-10-09
I'm a (mere) evolutionary biologist but my first guess you didn't mention. To me it reminds me of what happens when you pull your arms in and you start spinning faster due to conservation of angular momentum. Either from the initial compression from the water or the release of solvent pulling the denser parts inwards.
Jets of solvent probably sufficient though!