Self-Healing Material

[@SteveMould]

"Two by two, hands of blue" If you're interested in the Patreon livestream (they happen every other month!), you can sign up here: stvmld.com/43aib446 We also run the Q&A through Discord voice channel so you can ask questions with your actual voice! The sponsor is Wondrium: Signup for your FREE trial: ow.ly/Hqgn30skwQt

[@aaaaaa-rr8xm]

1k views in 4 minutes, congratulations!

[@Godwinsname]

What's the deal with Patrick Stewart? I feared he died seeing those candles.. :o but he lives, luckily :)

[@julian-io5wl]

If this polymer is crosslinking at room temperature how can it be that there are stil functional groups available for the self healing process. Normaly you would expect them to react with other functional surroundig them. I can imagine that there are weak chemical bonds that are broken(maybe by UV-Light) and reform all the time and when two seperate pieces come into contact they will also form between them.

[@Ezzell_]

Using the phrase... self healing....i would expect that if you scratched it...the scratch would heal.

[@MoistBrick]

From the first three minutes, it can be inferred how cold welding works in space; since there's no oxygen covering the metal, it allows the ion lattices to re-bind.

[@ruebancastro3189]

'I can't put metal back together.' then cuts metal and tries to put it back together. Scientific method at work. I love you Steve, make it tangible for us all.

[@tehs3raph1m]

just wasnt pushing hard enough... friction weld my guy

[@jaimedelgado7529]

Mercury

[@Twargan]

@@tehs3raph1m you're right and wrong. Welding metal happens from either heat or pressure. Or a combo of both. Something like tig welding would be 100% heat where as explosion welding is 100% pressure. Friction welding is a combination of both.

[@sethreign8103]

Some people just need a visual for what pressing two pieces of metal looks like for some reason.

[@superoxen]

Works for gold

[@loganh2735]

"Cold welding" totally blew my mind, and learning about it made it much easier to understand how a similar effect is possible here on earth. Awesome video!

[@DragonMan-tj3eg]

Holy shit you just made me realize that too

[@loganh2735]

@@DragonMan-tj3eg Glad to help!

[@chiryosaki5682]

Take a micrometer and tighten it with force. Also cold welded but not in a vacuum.

[@ykshay]

@@xenstence yes, I'm 5 days old and I know about cold welding, I can't believe these freaks don't know about cold welding bro, heh

[@KuraiKuroNeko]

Same, but now Sci Fi really feels more fictional, the more we learn about the true nature of space... imagine how many metal things could accidentally touch eachother in random situations, or the regulations created around the material plus alternatives potentially found that might replace metal, if we really became a space-exporing species. The possibilities are fun to imagine, for new-age Sci Fi media that features updated sciences!!!

[@Giraffemini]

Asking the question "Why DONT things heal or stick back" is such a great explainatory tool here! I wish some of my teachers had that way of explaining stuff back in the day.

[@kmktruthserum9328]

I highly doubt I would have paid attention to them still😂

[@hirotakasugi4891]

I dunno man, I’m pretty self-healing. I reattached my foreskin.

[@Idiot-Moose]

0:43 why is everyone ignoring that he has a Patrick Stewart shrine?

[@hugoperhammer]

Why would you point that out? Is it very different from your or anyone else's Patrick Stewart shrine?

[@Idiot-Moose]

@@hugoperhammer I don't have one 😔

[@Isolanporzellator]

A part of our group happens to be working on exactly such polymers, so I am somewhat familiar with the topic. There are 3 main ways to get self-healing polymers (sorted from least likely to most likely to explain this polymer): 1) Simply using a highly elastic resin, which causes stress to deform the material rather than break actual bonds. Over time and sometimes with a bit of heating the original shape is restored. An example of this being used is the "scratch shield", which is a highly elastic clearcoat used by Nissan to give their car finish the ability to heal moderate scratches by itself. Clearly your material has bonds fully broken upon tearing, so this is not the technique that's being used here. 2) Separated reservoirs of unpolymerized monomers and initiators/crosslinkers/catalysts. These can be either capsules or vascular systems spread evenly throughout the polymer. Upon injury, the monomer spills into the cracks and comes into contact with the initiator/crosslinker, causing it to polymerize and heal the injury. An early example of this is the use of Dicyclopentadiene monomer capsules that, when released after an injury, are polymerized by Grubb's Catalyst through an olefin metathesis reaction (doi.org/10.1038/35057232). The healing process uses up monomer and thus can only be performed a very limited number of times. In case of a full tear, the spilled monomer would polymerize on the loose end. Once fully polymerized joining the ends would no longer cause the polymer to heal. It seems unlikely that this technique is being used in your material. 3) Reversible bond breaking and formation (Also called "Intrinsic self-healing"). Polymers of this type have specific functional groups that can connect and disconnect with corresponding groups in a reversible manner. After a tear, rejoining the ends causes loose chains to reconnect to each other, healing the polymer. Closed chains can also be opened and then rejoined to form new links. There are numerous ways to achieve this, some examples include: 3a) Reversible formation of covalent bonds, for example via Diels-Alder-/Retro-Diels-Alder reactions (DOI: 10.1126/science.1065879). Some chemical bonds can be reversibly broken and reformed. After joining the ends together, chains in both ends can break apart and recombine with chains from the other end, reestablishing covalent links. Usually, energetic triggers like heating or UV-light are required to facilitate the mending process. You did not use any such triggers, so this is probably not what you have. 3b) Reversible supramolecular bonding. I am quite certain that this is what makes your polymer mendable at room temperature. There are several interactions that can cause polymer chains to stick to each other without any covalent bonding (ionic attraction, coordinative bonds, hydrogen bonds and π-stacking interactions). These can sometimes also be broken and reestablished at room temperature. You can imagine these supramolecular polymer networks to be like ball and stick magnet toys for children. Your sticks are short polymer chains with negative endgroups (ionic groups or chelating Lewis bases) and your balls are positive metal ions. The combination of both can form large networks of interconnected or entangled chains. The sticks can be flexible, but are not broken apart easily. However, the forces connecting balls and sticks are much weaker and so these connections can be rearranged with a relatively low activation energy, causing the material to stick to itself easily even after being fully disconnected for a long time. Even lower activation energies would be needed for hydrogen bonding networks (replace opposite charges with hydrogen bond donors and acceptors, H-bonds are significantly weaker than ionic bonds). An example for this is published here (doi.org/10.1038/nature06669). I think self-assembly via hydrogen bonding is the most likely explanation for the behaviour of your polymer, though of course I can't say for sure. An interesting example of an elastic polymer that sticks to itself but not other stuff is Parafilm, which is just a mixture of polyethylene and wax. It can't truly "self-heal", but it goes to show that even much simpler polymeric systems can show some of these properties. I just wasted an hour of my time to write this... oh well.

[@629Justme]

No you didn't. You are among interested parties. Well, I am. Have you posted on Quora? Another place for detailed answers.

[@hyperplayability6290]

Not a waste. Was very interesting to read :)

[@crackwitz]

This post needs to be... stickied!

[@coltongerber1879]

You did what I do when I see a video touching on some area of materials science I know about! Glad to know I’m not alone

[@psilovecybin5940]

You shared knowledge. No waste of time at all. Thank you very much thats was very informative.

[@SunderMun]

At Uni I did a project on self-healing materials, taking inspiration from Mussels. We were trying to replicate the self-healing properties by making an organometallic aerogel. Was really interesting but the scope ended up becoming multiple PhD thesises (no idea how it ended, if it has yet)

[@shinybreloom4027]

please tell me more

[@articxunodorseggnej8016]

Big brain clams

[@xsatsuki98x]

That sounds cool! I can't wait to read your publications soon

[@marcusrobinson1778]

@@xsatsuki98x he said he didn't publish

[@warfootages5578]

CAN I HAVE your Email ? Or any Contact information?

[@MadeInFranceASMR]

So is this like an atom-level Velcro?

[@7evYT]

YES!

[@TheLouisph]

not really

[@Eznet089]

How are these sub comments so different lmao

[@7evYT]

@@Eznet089 Most likely because every individual believes their opinion is the right one. 😄

[@CanIHasThisName]

@@7evYT In this case it's down to how strictly you want to follow the definition of each thing. Velcro doesn't really bond, it hooks.

[@x_dgaz]

This material repairs itself better than I can repair my life

[@williamm4366]

No you can do better, you can go into your local club of brazilian jiujitsu and never quit.

[@x_dgaz]

Ah yes, thank you

[@weary123]

True

[@autumn689]

Ngl this self healing material reminds me of skin

[@helloworld2409]

buddy a broken window repairs itself better than i can repair my life

[@miriamrosemary9110]

Thanks for explaining why things that are broken apart and not sticky don't self-heal/weld! I never knew that! And also that polymer seems really cool and probably has tons of applications :)

[@purplepowerranger23]

I immediately thought of resealable food packaging

[@sphygo]

It does indeed. It's called self-fusing silicon tape and it's used mainly for pipe repairs and thermal/electrical insulation in areas where temperate or moisture makes regular adhesive struggle. Only downside is how hard it is to remove afterwards since you can't just unwrap it like tape, it has to be cut off.

[@frailvoid5844]

Yoo you’re right about the many applications like I just thought if they made condoms with this material it could save us a lot of trouble and maybe even spare some of us from the agony of existence

[@navster100]

@@frailvoid5844 it would be really hard ot get off after

[@2lefThumbs]

@@frailvoid5844 yeah, but you'd have the more important agony of tearing the damn thing off

[@collinandersen3369]

You don’t know how long I’ve been wondering why metals don’t self heal. I asked this to one of my metallurgy professors and he acted like I had asked a stupid question and blew me off. Thanks for finally scratching this irritating itch!

[@keykilla78]

Must not be a very passionate professor then, either that or he didn't know himself and didn't want to admit it. You'd think they'd be exuberant to have the opportunity to explain the finer details of their field of expertise to a genuinely curious student.

[@KaliTakumi]

Willing to bet he didn't know the answer and thought it was a silly question to wonder in the first place. Oh how wrong he'd be

[@elevatedaspirations]

@@keykilla78 not everyone can be perfect at their jobs

[@danieldimitri6133]

There are actually videos of microscopic gold wires self welding in microprocessor production or something to that effect.

[@jondo7680]

That's why stupid people are happier. If you would be to stupid to ask this question or if you would be that stupid professor you would be happier than knowing how stupid that person actually was to you.

[@dwo356]

It is so awesome that you anticipated the question of what would happen in a vacuum when discussing cutting a metal. It was the first thing that popped into my mind and I'm so thankful I didn't have to ask or look it up. Thanks!

[@shinesunarjo3638]

Thats what makes him great

[@LGreenGriffin]

I typed the comment, thought to myself, "Wait, he'll probably address this," and then an astronaut appeared.

[@benjaminsmith3625]

It's left me wondering about non-oxygen atmospheres though!

[@scottb9997]

If you do want to go deeper the process is called cold welding

[@tissuepaper9962]

@@scottb9997 yeah lol cold welding was my immediate first thought when he asked "why isn't metal self-healing?".

[@rebecacedeno1856]

I think the mechanism that puts the pieces back together is supramolecular interactions. The polimer chains are functionalized, at their ends there is an additional bonding, like a puzzle piece. So when you put them back together the puzzle pieces at the end of the polymer chains meet the other puzzle piece.

[@fedormedin8861]

Can it be a 2d polymer? Two polymers reacts not only on ends but on long parts of molecules

[@supercuriousbrain]

Great analogy

[@nathanaelvetters2684]

Yeah. The selectiveness of the reactivity is interesting though. It needs low activation energy, doesn't react with simple ions or molecules like from air or other surfaces, but very readily reacts with the end of another polymer chain. It really must be like a puzzle piece with a specific shape, but then what keeps some oxygen atoms from coming together and taking up part of the open reaction site, blocking another polymer chain from bonding there?

[@eeurr1306]

@@nathanaelvetters2684To actually find out, wed need to calculate the electromagnetic fields with 100% detail.

[@AutistiCat2406]

Yeah but that means repeated use can make it worthless because itll all bond back together like a normal polymer at some point

[@petergoestohollywood382]

“Cold welding” doesn’t actually have to happen in the vacuum of space. From experience I know that if you polish two quartz glass plates very flat and smooth and then stick them together, they will permanently bond as well. It’s pretty awesome!

[@calipete]

This I would like to see! I've never heard of that.

[@Gti_Jason]

@@calipete I've been able to Lap 2 copper heatsinks so "flat" in terms of the bottom surface of one and the top of the second that they transfer heat as good or better than with thermal interface materials. I'd say what happens would be called "Wringing" The phenomenon you speak of is routinely used to test the flatness of precision gauge blocks used in metrology: their ability to "wring" together both confirms their flatness specifications and is useful for storage, when a very light film of oil enhances the wring - and thus keeps corrosive environments away from the calibrated flat surfaces when the latter are not in use. Wringing is thought to be a combination of . . . 1. Molecular Attraction - accidental cold welding or, as Richard Feynman put it, when the interfaces between like materials are very flat, there is "no way for each atom to know which block it is in", so the bond across the interface gets more and more like the normal molecular forces holding the lattice together the flatter the interface 2 Suction - i.e. the blocks have expelled air from between them and air pressure helps force them together 3 Surface Tension - From any water vapor that gets caught between the blocks.

[@Meme-2038]

Cold welding is with metal, you said that happened with quartz without a vacuum. Quartz is not metal, it is a crystal

[@janvisagie231]

@@Meme-2038 I thought glass is amorphous not crystalline.

[@FaeAstray]

@@janvisagie231 Quartz and glass aren't the same.

[@JohnBaleshiski]

Love your humor of putting up a Patrick Stewart (fixed) shrine. You are fantastic. Thanks for regularly making us smarter.

[@aneeveewhohasinternet1871]

This guy is amazing lmao

[@BirdThatEatsPrometheussLiver]

Humor? /j

[@ehsanalmassi453]

I thought he had died and I quickly rushed over to google. He is not dead

[@nipun108]

@@ehsanalmassi453 yeah same. This joke confused me, lol.

[@tjenadonn6158]

@@ehsanalmassi453 Bold of you to assert that Patrick Stewart is mortal.

[@lidarman2]

I use a self-amalgating tape all the time at work and yes, you stretch it to activate it. It actually does a great job sticking to itself when you do it right. And to float a ship in a gallon of water you simply make the container the same shape as the ship so that a thin film of water floats the ship up to the draft height.

[@Validole]

You just need a really small ship. In all honesty, I somehow doubt it would work? A gallon of water would need to be raised very high to counteract the force of the ship. If you made such a container, the ship would simply settle to the bottom of the container and push out all of the water.

[@bismuth7730]

Ship could only float if it displaced the same weight of the water, so the ship would need to weigh just as much as a gallon of water.

[@lidarman2]

@@bismuth7730 The ship can displace the weight of the ship in water with only a gallon if the container the ship is in is strong enough and can fit snugly against the ship. Here is how. Take the snug fitting container (Which has a height of the draft of the ship and fill it with water. Now place the ship in the water. It will displace the weight of the ship in water and float with a small amount of water between the hull can container. The rest of the water displaced will overflow the container and be gone. Now if you remove the ship, there will be hardly any water in the container. You will get the same result if you just start with that small amount of water. One does not have to literally displace the weight in water, one just has to effectively do it.

[@saltananda3227]

@@Validole the container would go half way up the ship, be perfectly formed to the ship (but allow a slight gap evenly around), and sealed airtight. The pressure of the ship would be evenly spread upon all the water encapsulating it, therefore it wouldn't sink or hit an edge unless an external force was applied. Basically a "shell" surrounding the ship with a thin layer of water.

[@2869may]

@@saltananda3227 Can you elaborate on how the "sealed airtight" part works....?

[@teo_lp]

I may have experienced a self-glueing sticker once. This vid left me thinking if it was something similar. It was in an airport, a self-service baggage drop-off station automatically printed the long paper strip that you attach as a tag to your bag, with its identifying information. I remember the tag had one printed paper side, and another plasticky side that surprisingly didn't stick to your hands but glued firmly to itself when you bent it around the handle of your bag and made it touch itself. I remember being baffled that it didn't feel like the familiar adhesive side of a sticker at all. It didn't stick to the handle of your bag either which made it really convenient to detach later without leaving residue. Has ayone else ever come across this?

[@NathanielCoran]

4:41 Sorry to have to correct the science here, but I think you'll find that a Polymerization reaction is actually when you send two or more monsters from your hand or field to the graveyard in order to special summon a fusion monster that lists those monsters as fusion materials from your extra deck

[@MexNoir]

shit he's right

[@Dexuz]

Unexpectedly expected comment.

[@humphreywolfe]

*Yu-Gi-Oh Master Duel moment*

[@PixelionRules]

Yes.

[@Hdx64]

I ritual summon a like for you, put a card facing down and I'll end my turn

[@BlackWolf42-]

Steve, when you join those two pieces together, is the reaction endo or exothermic by chance? You probably won't be able to feel it but a FLIR camera may show if it gets warm or cooler.

[@SteveMould]

Really good question. I might give that a try. Need to find my FLIR. The issue is I push it together with my fingertips which would probably swamp any slight changes in temp.

[@iangabriel5536]

@@SteveMould If you do, please update us!

[@Lishtenbird]

The process did remind me of metals getting welded back at high temperatures. But surely if (low enough) pressure moved the melting point to room temperature, this would've been noticeable in general use...

[@elliotmarks06]

@@SteveMould it also may be hard due to heat from friction...

[@edwardlees4585]

@@SteveMould Can you push two ends together with two wooden spoons or plastic tongs to avoid heat transfer?

[@Charles_Snow]

I've always wondered what makes something "self healing". Ever since I bought a self healing cutting board for crafts. I'm not sure if it's made of the same material. Thank you for another amazing video!

[@TimothyFish]

Self healing craft boards seem to be rubber glued to a base that is hard to cut. The rubber doesn't actually heal, but the slits don't remain visible because the base keeps the rubber in place.

[@axuwu6939]

@@TimothyFish This should be easy to test out by making a cut then pulling at the sides! I want a self healing cutting board to try this now. For science!

[@JungleLibrary]

Self healing cutting boards are different, they basically compress the surface rubber so that if it's cut, the compressed rubber expands to fill the gap, but it only works so many times

[@jasperfk]

@@TimothyFish I vaguely recall some self-healing cutting boards that have micro-tubes of epoxy resin which ‘heal’ (fill) lacerations in the cutting surface, too.

[@maxnovakovics2568]

@@TimothyFish i knew it wasnt self healing when i saw the one on AvEs bench

[@Rappid_]

i have no clue what this man is saying but also understand it all in perfect detail

[@jonathanCRoberts]

You're obsession with Patrick Stewart is so... understandable and relatable. Thank you for sharing this passion with the world!

[@ommsterlitz1805]

It's more like a passion for Jean-Luc Picard

[@Grandwigg]

Sir Patrick Stewart is responsible for my Earl Grey addiction. It's nice to see kindred spirits. (Also, the Captains series interviewing the actors was amazing)

[@horacegentleman3296]

Only if you pretend the Picard series isn't real.

[@daltonwatson2058]

Sir Patrick Stewart's favorite cartoon is Beavis and Butt-Head.

[@Somethingcorporate99]

This is really interesting, I have "self healing" cutting mats for cutting fabric on and always wondered how they were self healing

[@jek__]

I believe those operate by a different principle- Self healing cutting mats are basically super dense and short brushes, so when you cut into them your blade goes between the bristles. It's less that they self heal and more that they avoid being cut in the first place

[@ivan_valerian]

@@jek__ I dont think that they're self healing at all even, cause when you bend the mat in the opposite way, you can see the creases and cut on the mat itself

[@ErisApplebottom]

@@jek__ thats cool, i want one

[@deletedddddddddd]

self healing mats dont actual heal, theyre just dense plastic that when cut it shouldnt leave ridges but they usually do...

[@makosen]

Majin Buu paper

[@humanistwriting5477]

I think this material is awesome, I am going to share this with my boys for sure! Just for engagement; Another cool thing about metal cold welding is that you can do it in the atmosphere! Obviously with gold, but also with oxidizing metals you just have to design the joint to push out the oxidized material as the material is pushed together But, even then there is an amount of time that you have to wait while holding it all steady for it all to weld together, it starts at random locations in a process called galling, and eventually becomes one solid unit. The amount of time is dependent on the temperature I find it absolutely crazy that there is amount of contact time required for the metal lattice to fully recognize that its one unit again!

[@takuma359]

big brain

[@AkiSan0]

well, as with crystallization lattices dont magically occur. ;)

[@takuma359]

@@AkiSan0 also big brain

[@GogiRegion]

I know this is another example of a sticky thing, but another self adhering polymer that people see in everyday life is gluten. To simplify it a bit, gluten proteins have long amino acid chains that can link together both end to end to make the chains longer (the primary purpose of kneading dough), as well as side chains with thiols that when hydrated can bond to each other so the chains connect. When both of those interconnect a lot, it creates sheets of connected parallel protein chains.

[@conkerthesquirrel4331]

I'm an injection molding process engineer and this is one of the most interesting things I've ever seen on the internet. Making flow fronts "re-bond" after they go around a core or other feature in an injection mold is a very difficult. We look at is a minimizing the weld line as you can't make these polymer chains truly re form. Typically this is done with greater injection speeds or higher temperatures. Albeit, greater injection speeds induce shear, therfore.. also heat related. Very very cool video. Thanks Steve!

[@ItsWaltieTime]

This explains why I find so many plastic water valves that fail at the seems in the equipment I service. Mystery condensation appears in the cavity... follow the mist.... mind boggling micro hole allowing water to leak. You'd never see it with the water off, looks perfectly solid.

[@pumpkinpooper]

Uh..sir with that pfp ,sure we all beleive u really is an engineer molding process injection

[@lizard-breathOG]

@@pumpkinpooper not to say it doesn’t take intelligence to do what his job requires, but I ran plastic injection mold machines since I was like 12 in my dads shop. You have to understand what the buttons do, how to change the molds in and out, how to unclog it, and what to do when the plastic is shooting into the mold weirdly. Plus a few other things I’m sure I missed.. now granted, that is only one type of machine that’s usually in these shops, and if you have multiple of each type of machine, it’s usually from different companies so they all run differently. (These things cost around $150,000, from what my dads told me) I personally don’t know how to do all of these things, seeing as I only ran machines as a teen in the summers every year until I graduated. I never did most of the other stuff personally. but my older brothers and dad do. All it takes is working in a machine shop for a few years and having someone teach you everything through those years. It’s just like being a mechanic. You have to understand the machines you work on, and that they’re all similar but still have important differences. that doesn’t require a degree, it just requires on the job learning for years!

[@pumpkinpooper]

@@lizard-breathOG i do respect u for explaining this , dear lizard breath. btw u said it does not require a degree so basically what ur comment is implying is that the orginal person who posted the main comment is dump.. ? right if thats what u are implying , i am 100% agree with u that guy is probably dump{guy posted main comment} u sir are a chad giga cool chad

[@lizard-breathOG]

@@pumpkinpooper well, I’m not saying he’s dump😂 more so I mean, he probably has put in a lot of work over the years to learn all these things, but it’s not like you need a degree to do it. (So I don’t think he’s stupid, you just don’t have to be a genius) It’s just on the job learning for a long time. The machines are actually pretty complicated and some of them have like 40 buttons or touch screens. And you have to know how to download the info from the computer onto the machine, but I think that just takes knowing how to open files from a USB stick onto the machine. Also the molds in the plastic injection machines are anywhere from about $8,000 to like $200,000. It just depends on the size, how complicated it is, etc. so the fact that he’s the main engineer guy means he’s proved himself to the company with his knowledge and productivity! Also you have to be hella strong to move those things. One of my brothers lost a finger cause he wasn’t paying close enough attention when putting a mold in the machine 😂 I bet this guy is just your average machine mechanic/operator who has learned his specific trade well!

[@DEtchells]

I used this stuff for ultra-waterproofing a fiber optic connection. It worked super-well. Here in the US, you can find the stuff under the brand name of X-Treme silicone rubber self-fusing tape. Very useful stuff, and it really does fuse to itself; once it’s together it’s a solid mass that you have to cut to separate. It takes a second or two, but you need to make sure you put it where you want it!

[@dickJohnsonpeter]

Awesome! I just ordered some on Amazon. It looks like this stuff is pretty common so I'm going to look for it in the stores now.

[@tasnimulsarwar9189]

@@dickJohnsonpeter kindly update if you can after you had some experience using it.

[@Dpix1990]

It's called SOS Silicone Tape here in Australia if anyone is looking for it.

[@dickJohnsonpeter]

@@tasnimulsarwar9189 will do.

[@tasnimulsarwar9189]

@@dickJohnsonpeter thank you good sir.

[@jmmahony]

Unintended cold welding in space also happened on one of the Gemini missions, when they opened the hatch for a space walk. As the hatch hinges opened, the scraping between the two metal parts of each hinge cleared away the oxide layers enough so that the two parts of each hinge started to weld together in the open position, so when the walk was over they had a hard time closing the hatch.

[@HawtDawg420]

Interesting! Unfortunately though, a quick Google search led me to articles that say that while cold welding was originally thought to be the culprit, a SPRING that failed to compress was the real cause of the hatch not closing. Still, it's an interesting phenomenon that I had no idea about.

[@melody3741]

Nope - it was a theory but not what actually happened.

[@paaaaaaaaq]

@@melody3741 Bang! Debunked! Hang on a second, what happened then?

[@EazyDuz18]

space is fake

[@isadorah4969]

I used to always ask myself as a kid why cut things can't be put back together. Then I graduated at Chemistry but never realized how obvious it is LOL Prob because I work with water so no time to think about materials anymore. Thank you for pointing it out! This self-healing polymer is indeed very interesting

[@christatler7378]

In the electrical industry we use a tape called amalgamating tape. The tape is used for wrapping up joints made in cables that are outdoors like power lines. It is extremely stretchy and when applied it is stretched an wrapped around, and as it tries to shrink back it kind of bonds and the layers stick together similar to the polymer in the demo. I was always fascinated by this tape but couldn’t work out how it could work because it wasn’t sticky. What’s even more fascinating is why most materials don’t bond back together. Good demo and liked the shrine to PS.

[@markusschnepf]

honestly, I thought the thumbnail image was clickbait. I DO know these "self healing patches" that have small pockets filled with glue. but this polymere is impressive and so are Steve and his videos

[@jam99]

I never go anywhere without self-amalgamating tape.

[@VulcaNtGoF]

@@jam99 Nor do I. I used to manufacture it, so I have literally dozens of pounds of the stuff in multiple sizes and colors.

[@10yrs.istillcantthinkupawi11]

Dude I am actually blown away and baffled by the oxidation explanation. I just assumed that when you cut something (specifically metal) all the particles just naturally start to reorient to compensate for the new gap in space that is created and so when you would try to rejoin the two points they would just naturally start to repel because of the new orientation of the atoms would cause electrons from one piece to be repelling of the electrons on its counterpart and so on and so forth... I really want to see two solid pieces of metal rejoin into a singular piece in space right now oh my God that sounds amazing

[@joeshmoe7967]

Or here on earth in a vacuum chamber? I am hoping some youtuber tries this. I would have to see it to believe it.

[@beeble2003]

There's no orientation. The electrons around atoms are in constant motion so, when you ionize an atom by removing one of the electrons, that positive charge isn't localized on one side of the atom.

[@hawq2483]

kzbin.info/www/bejne/ppLZoWmapdhpp5I

[@hawq2483]

kzbin.info/www/bejne/op-6cpieorGbrrM

[@wyattoutlaw2370]

I don’t think that’s true. Metal won’t stick to itself just because it’s in vacuum.

[@Grey8405]

Why do certain polymers self-heal? - ChatGPT "Certain polymers are able to "self-heal" due to their unique chemical and physical properties. These polymers have the ability to undergo reversible cross-linking, which means that their chemical bonds can break and reform in response to a stimulus such as heat, light, or pressure. When a crack or cut forms in the polymer, the broken chemical bonds can reform and heal the damage. This process can occur spontaneously at room temperature or with the application of external stimuli. The healing process can occur on a molecular level, allowing the polymer to repair itself and regain its original strength and properties. Self-healing polymers can have many practical applications, including in coatings, adhesives, and electronics. For example, self-healing coatings can prevent corrosion and wear on surfaces, while self-healing adhesives can improve the durability of joints and connections."

[@luci4087]

0:44 the “shrine” to patrick stewart. lol nice.

[@tenorHarlequin]

This man literally answered every question that popped into my mind as they popped up.

[@patmat.]

Awesome perspective, as a mechanical engineer I understood that glueing happened mostly at the molecular level but I never thought about it for metal or plastic cutting.

[@RealValkor]

Not gonna lie, I got mindblown to know about metal being able to glue back togheter once there is no oxygen.

[@liandoaethend2403]

This teaches better than the chemistry class in my school

[@EthanNeal]

2:45 if I remember right, it is possible to cold weld some metals even in the presence of oxygen. You just need two surfaces that are flat enough that don't oxidize and then squeeze all the air out from between the two pieces.

[@SianaGearz]

I've heard it said that you can cold weld gold on Earth but it takes something like centuries.

[@alexoja2918]

Some machined surfaces will stick to each other really strongly. Feels like a weld but it breakable.

[@talibong9518]

Like explosion welding, where 2 sheets of metal are forced together by explosives that squeeze out everything in-between them.

[@jeffs-reviews]

Take two blocks used to measure calipers, the smoother and more parallel the sides the better and they will stick to each other without any glue or "healing"

[@SianaGearz]

@@jeffs-reviews The blocks are very smooth and covered in a layer of grease. If you follow a procedure which pushes out the air, what you get is blocks held together essentially by vacuum, not too different from a suction cup on a tile. They will not weld together.

[@juliusc.2088]

Have you read into the following paper: 10.1038/s41578-020-0202-4 I belief there is more to it than the localized chemical reactions that you also mention (i.e. polymerisation). Aluminium, for example, can also have a variety of self-healing mechanisms, e.g. based on a reaction with oxygen. The product (Aluminium-Oxyde) is not permeable to O2 molecules, so it prevents further oxidisation after physical damage to the surface. For the polymer, it might be that the force from pushing the two pieces together is enough activation energy to initiate reactions. If that would be the case, maybe a thermal image would indicate an exo- or endothermal reaction. You could also change the topological structure of the stripes to see, if that impacts the self-healing mechanism. Maybe some adhesion effects are in place.

[@TROPtastic]

I'm no materials expert, but I believe the protective oxide layer in aluminum is a different type of self healing than whatever is going on here, since that only protects against further oxidization (unless the layer is damaged) but it doesn't allow two pieces of aluminum to be joined into one after separation.

[@beautifulsmall]

Applied science channel Google scientist Ben Kraznow , this could be one for him. Super in depth science of the wonders of nature.

[@ssnjr1299]

@i don't make memes put it back then

[@SteveMould]

Hi Julius, thanks for the insightful info, really appreciate it. If you're interested in joining my Discord where we chat through ideas here's a one time link: discord.gg/VzsRmy7A

[@danielweller1291]

Hey Steve! Big time fan. Great explanation of a very cool material. I've studied polymers for many years and a common mechanism for self healing polymers is using monomers that bond to one another through an array of hydrogen bonds (typically 4-6) rather than a single carbon-carbon covalent bond. Because hydrogen bonding relies on secondary forces they can be broken and reformed repeatedly. There's other strategies too but I always thought this was a fun one! Loved the video

[@wiez543]

This is what I learned in Uni, too.

[@SteveMould]

Hi Daniel, thanks for the insightful info, really appreciate it. If you're interested in joining my Discord where we chat through ideas here's a one time link: discord.gg/UemmPhW6

[@randomstuffloool]

Props for the cameraman for going monucle size and recording the split

[@AngusMurray]

2:35 YOU just BLEW my mind! 🤯

[@NicosLeben]

2:30 But you should be able to fuse gold together because it's noble.

[@StevePittinger]

I just discovered this channel a few days ago, but it didn't take long to notice and appreciate the recurring appearance of Patrick Stewart. His appearance in the various contexts is, quite plainly, comedy gold. Thank you for mixing scientific learning with light hearted humor, it makes learning of new concepts that much more enjoyable.

[@joekrater3364]

hmm... gold cold welds

[@tylerplayzzrecroom]

Deadpool: "Oh, great, now they're trying to make another version of me! Does that copyright symbol even work?"

[@williamdrayer5166]

I suspect this is indeed a crosslinking reaction, and probably more specifically a tautomerization so that it can occur appreciably at room temperature (keto-enol is the simplest example for those unfamiliar, probably along similar lines due to the stability of the resonance structures especially with ketones but this is probably a more complex reaction). The (mild) pressure application probably pushes the equilibrium enough to significantly increase the crosslinking fraction. Probably also at play here is the viscosity dependence on pressure (and to a lesser extent, temperature). I agree it almost certainly is not self-healing capsules. playing with the pH of the polymer could also reveal the mechanism along similar lines to keto-enol structures requiring the proton in the pseudo-ring. source: polymer engineer PhD candidate

[@hitmanRazo]

I'll take your word for it lol

[@Defensive_Wounds]

Is this why even when he crushed it in his fist at 7:15 while trying to pull it apart, it still stuck to itself?

[@tonyguy9762]

Tautomerism requires strong reagents, typically something like sodium hydroxide (aqueous) would be able to produce conditions that would yield less than one percent resonance structure (enol) and this would only occur in polarising conditions. In the solid state molecular collisions are unlikely between the two surfaces in same way as if in the liquid phase. Also you would expect a product of a tautomerism reaction to have to leave the chemical system to drive such a reaction, for a stoichiometric reaction you would require reactivity to the order of say sodium hydride, and then it would have to evolve an equivalent of hydrogen. And the material is in its solid state, between the lower glass transition temperature and the melting point, so viscosity isn't relevant. I suppose ligation due to the molecular motion exhibited by elastomers in that range could be called solid state complex formation. ATB with the research.

[@williamdrayer5166]

@@tonyguy9762 my mention of viscosity dependence on pressure precisely points to the idea that the added pressure may induce more liquid-like behavior. I'm more confused that you mentioned this is lower than the glass transition but also call it solid state: I particularly study polymer glasses (or supercooled liquids, if you prefer) and particularly object to calling a glass a solid. There is no distinction between the molecular behavior of a liquid and a glass, so the collision behavior should be indistinguishable. Viscosity is absolutely relevant: glasses only appear "solid" to us because of the mismatch of viscosity (or relaxation time) and the observation time window (for us humans, on the order of tens or hundreds of seconds). I certainly do not deal with chemistry much, so I have no guess as to that. But this is clearly an amorphous crosslinked polymer, that appears to form crosslinks when pressed together.

[@williamdrayer5166]

@@Defensive_Wounds yes this was part of my thinking

[@diarya5573]

One of my biggest aversions to material sciences was trade secrets. It's such a stupid thing getting in the way of faster growth, I tended towards things that, you know, can't be patented

[@mattheffron391]

In terms of propagation of the information and growth of the knowledge, patents are nearly as good as "freely available". Neither keep the information secret. Trade secrets are, by definition, secret. However, if discovered independently and disclosed, the trade secret has no value per se.

[@kjdude8765]

@@kirayoshikage4057 I tried reading this with an open mind but I couldn't figure out any way to read this and it not be totally racist.

[@diarya5573]

@@kirayoshikage4057 Mmm yeah the rich white elites definitely don't play their part in screwing everyone else in the world eh

[@TomFoolery9001]

@@kjdude8765 Yep, anyone who really believes what he believes is just out of touch with reality. Greed is very independent of any religion and tying it to one religion is just crazy and stupid.

[@RoflcopterLamo]

@@kjdude8765 what he say?

[@gabbylikeskicks]

0:40 legit checked if he was still alive after I saw that

[@AshrellStudios753]

So is he?

[@stan52323]

​@@AshrellStudios753 Google it

[@Kelvinkelvin666]

@@AshrellStudios753ya

[@CYNTH_14]

​@@AshrellStudios753HE'S STILL KICKING

[@coding01]

wait why wouldn't he be

[@lgbthater]

These are the kind of people who give me hope for KZbin. Scientific content that is creative, informative, and actually gripping. Makes me wonder what my science teacher was doing 😂 Amazing job Steve!

[@gregbits6109]

When the question’s first reversed I just assumed it was to lengthen the video, but I’ve actually never thought about what makes things NOT stick together…

[@faucamargo]

You blew my mind! Im a materials engineer and never really gave thoughts about this... amazing content!

[@BloodyProphecy]

@1:30, you simply are not pushing the two pieces of metal together HARD enough.

[@Owen_loves_Butters]

Because he's not a hydraulic press

[@AirNorthOne]

They have this issue in space, where oxidation is very slow to nil due to lack of oxygen. Tools and stuff get fused... cold welded mentioned at 3:00

[@lincolnsghost7328]

This thing about the cold welding of metal in a vacuum is something I’ve never seen or heard represented in science fiction.

[@mattheffron391]

Similar to cold welding, I recall seeing a discussion in a Caltech publication that cleaving a diamond in a vacuum would leave 2 surfaces that could be brought back together and rejoin. IN THEORY, if the surfaces were perfectly realigned, then the diamond would have no optical defects evidencing the cleave and rejoin.

[@alexlutz2221]

@@MonkeyJedi99 Gage blocks aren't wrung together causing the same type of thing as the tape though. I believe it's due to them being such a tight match that wringing them pushes most of the air out of the gap creating a slight vacuum. Not completely sure on that but I do know that it's not magnetism as I believe ceramic gage blocks will do the same thing and it's not cold welding as the joint isn't strong enough for that and there is a very very small oxide layer formed almost immediately when metal is machined and these blocks sit in a box specific gage blocks potentially not being used for years and then will still wring together.

[@MonkeyJedi99]

@@alexlutz2221 I did not even hint at magnetism, and I think you are right that the precision surfaces "wring" because of vacuum.

[@jsmith5443]

Cool

[@blazernitrox6329]

If I understand correctly, something similar to the micro-encapsulation theory is exactly what happens in bird meat. It turns out you can literally pound a chicken breast into a flat sheet and it will remain as one solid piece of chicken, whereas doing the same with a steak will just cause it to shred. Apparently bird muscles get torn so often during flight that they evolved a special chemical for fusing the proteins back together, but only inside of a short timeframe. Cooking the meat decomposes the protein and the chemical itself, which is why you don't end up with chicken amalgam in your gut after you eat some General Tso's.

[@MeltedMask]

Interesting, must be related to 'meat glue'. Btw, main function of stomach is to denaturate organic chems and decompose proteins to aminoacids. So there is zero change it to bind with gut, even if you eat raw meat.

[@ruckbarbie]

Thissss is how the channel got into my algorithm. I apply paint protection film on cars for a living. Our greatest marketing tool is a film on a piece of plastic we let customers hack up with a screwdriver and then place under a heat lamp for "magic healing." Anyways, happy I found this channel :)

[@volundrfrey896]

There is this "self vulcanizing" (not sure if they're called that in english) rubber strips you can buy that does this too. They're been around for ages. Really cool stuff, I think it used to be popular for handles of different kinds before single piece stuff became cheap.

[@DrNEMO]

You got me with your little Patrick Stewart altar 😂 Beautifully explained and incredibly entertaining, as usual, Steve!

[@MrM6d]

But just a hedge bit creepy too.

[@КочетковІванВікторович]

@@MrM6d You don't have little Patrick Stewart altar, do you?

[@MemekingJag]

@@КочетковІванВікторович he doesn't have a little Patrick Stewart altar >.>

[@meekotheotter2801]

@@КочетковІванВікторович imagine not having a Patrick Stewart altar haha, this guy must be really boring and weird

[@JamieBainbridge]

Excellent Patrick Stewart shrine, happy Captain Picard Day!

[@SciTechVault]

A quick literature survey using Google Patents can reveal a lot.

[@bloodmoondefense]

Tape that only sticks to itself? Sounds like every time I’ve ever used any kind of tape!

[@HenryNewbury]

Great to see Patrick supporting such a great channel ❤️😛

[@lucashenning3158]

My first question as you explained the oxidation of metal was "would metal fuse to itself in a vacuum?", and you very promptly gave the answer. Great video!

[@KARAOKEMONTREAL]

Please be careful. In this video, at about the 7:30 time stamp, we see finger/thumb tips being used to push a sleeve back over the end of a hose. This is not recommended as you can easily snap finger/thumb tendons!

[@Owen_loves_Butters]

I'm pretty sure literally everyone has done that

[@ZoonCrypticon]

@2:40 So you might expect, that one day all the metallic space junk of destroyed satellites could coalesce into an unspecified metallic object (if the distances diminish , the velocities increase and more collisions take place on the "accretion" disk around the earth and the laquer surfaces get "scraped away " by the continuos electrons of the solar wind.)

[@iSmartMan1]

0:50 Controversial question: is water sticky?

[@Blobfishlovr69]

No it's wet

[@Kaplan_MT]

Except the white variant

[@firewhite]

@@Blobfishlovr69 it’s not wet

[@dangerparade2913]

@@firewhite of course it is

[@firewhite]

@@dangerparade2913 tell me, is fire burnt? i don’t think so, so why would water be wet

[@jhonbus]

6:34 forbidden mozzarella

[@canadiankazz]

Where were you when I was failing high school chemistry?! You explained things much better than my teacher ever did.

[@saccaed]

I have a roll of that stuff in my cars after I repaired a radiator hose during a road trip. The fix lasted the whole trip as well as the time needed to ship in a replacement hose.

[@ignaciosalazar6479]

Great video, I remember a type of tape used in electrical work, to terminate medium voltage ends, self-vulcanizing, or like PVC glue does in the fitting, chemically bonds

[@Alex_Deam]

1:51 I'm sorry but cutting that sodium looks way too satisfying. Please make a ten hour version.

[@nguyetha7280]

Well at first, i thought this video is gonna be about mental health, how to heal ourselves and things like that. It turned out to be about real self healing material, and the way Steve simply explains and provides scientific information about it was just... interesting :D the content was not what i expected it to be, but i watched this vid till the end and learn something new, thank you.

[@danielvalle3789]

I nearly fell off my chair over the Patrick Stewart shrine bit!!! Hysterical cuz it catches u off guard! Lol

[@ejoojoo]

hoping for a self healing 3D printing filament, it will eliminates layer separation and possibly making it non porous.

[@armadillito]

Now that could be amazing

[@ADBBuild]

How would you keep it from bonding when on the spool though? Perhaps some kind of coating that burns or melts off when extruded?

[@bluejayechaosenbybirb5865]

@@ADBBuild It might just be me, but when I think of coatings meant to be burned or melted off, I can only think of things that would either give off harmful fumes, making it impractical and unsafe to use indoors, or make a mess, potentially also mixing in with the filament as it melts. It may not be the most practical, but I feel some sort of removable thin paper shell similar to a straw wrapper could be a decent solution. Considering existing technology, a system to automatically remove and collect the paper as the plastic is printed seems fairly straightforward to design. There's also the added bonus of paper being recyclable; if the system of collecting the shell is efficient enough, they could even be directly used for multiple spools Well, if this sort of self healing material is even suitable to print with. It seems rather flexible, making it impractical to print anything intended to hold its shape Now, it's very likely that I don't actually know much about 3D printing or anything I'm talking about (after all, it's hard to know what information you don't have), but these are just my thoughts with the limited knowledge I have Wow this is a lot more words than I intended to type when replying to this comment

[@fuzzydane2090]

I think you might have an easier time post-processing existing filaments - it's possible to create gastight, food-safe prints on regular, consumer-grade fdm printers. Unfortunately I've signed an NDA, so I can't quite disclose how it's done :-/

[@SianaGearz]

@@ADBBuild You could have a carrier on the spool made out of... corrugated cardboard open on one side? Separating the layers of the plastic. You would have like a dozen or two loops side to side in their own wells, and once they're all unspooled, the cardboard protector piece simply falls down from the spool and the next layer becomes usable, and there'd be these between each layer. Honestly i haven't thought this through, i really don't know whether this would work. But it's a direction to explore, potentially, if the whole self healing filament idea has any legs to stand on - i really doubt. Another possibility is to rely on the mixing action of the nozzle, though unfortunately it's pretty weak, but maybe with CHT nozzle or an insert similar to those used in injection moulding, it could be improved. The filament could be coated with a barrier polymer that doesn't have the self healing property and prevents the filament from healing onto itself, but as it gets mixed in, during extrusion, the self-healing polymer gets exposed on the surface of the extruded bead. The fact that a very thin barrier layer would be sufficient is on your side, the barrier material could be barely a percent or less by volume and might not end up influencing the properties too much.

[@jelisontejada1758]

5:47 the one who tried to get away 😂😂😂

[@Difyht]

So when most thing cut off. They heal by itself quickly. Like the wound heal by itself. Just after it's cut, now it turns to two seperate objects. In another word, everything heal itself already.

[@beaudanner]

I always appreciate a visual gag like that. People don't understand that it takes hours of work for a 5 second joke like you did with Patrick Stewart. Well done

[@MrDowntemp0]

I want to hear more about how a tire is just one giant molecule please

[@kjdude8765]

Read up on Vulcanization of rubber. Basically sulfur is used to crosslink all the rubber molecules into a single durable one.

[@fluffypink90]

Look up "vulcanisation" for the process of cross-linking rubber as is done with tyres.

[@siberx4]

I use self-amalgamating tape to waterproof outdoor connections for coaxial cables on antenna systems (amateur radio) and I always found it fascinating. Works great for this application, and is almost impossible to cleanly separate once it has fused. Interestingly, I have found this kind of tape (even the black stuff) decidedly *not* UV-tolerant, and it will degrade and split quickly when left in the sun. Simply overwrapping the join in black electrical tape (substantially more UV-tolerant, despite also being a black plastic tape) does the trick to protect the amalgamating tape from UV though, and then it lasts for years.

[@noteroor4048]

everyday immortality is getting closer

[@AndersKvistDK]

Can this material be reused? The pieces you have cut and stuck together - would it be possible to mill them into a new sheet? Would it require heating up to make it easier to work with or?

[@Mill_O]

2:02 Never actually seen a close-up of a sodium-oxygen reaction quite that detailed before, nice shot

[@jasonchiu272]

Most materials: *Tries to join back together* Oxygen: "Hello I'm here to ruin your day"

[@budzillasohoski9858]

I literally sit down on the edge of my bed for like 20 minutes after I do laundry and try to figure out where the hell that one missing sock went…I’m 50…still no answer. You’re splitting atoms and polymer chains. You are a smart cookie.

[@___aZa___]

1:45 wait wait wait. so that means if you cut metal in a vacuum and put it back together it sticks? what the hell! you have to try that!

[@___aZa___]

ah, nevermind xD

[@Owen_loves_Butters]

Only if it was never exposed to air, since the oxide layer doesn't just go away.

[@Jhalling10]

You could also use gasses like how they to on TIG welders

[@midorifox]

7:50 well, you can just keep theorising, if you get a letter from the makers, it means you found the answer

[@Simbosan]

Good to see you have found a use for the tons of bead chains. I expect more polymer videos in the future!

[@every1luvsxeno]

[2:07] I'm just curious if we cut a metal in half in outer space, can we fuse the two metals together? because there's no oxygen, no oxidation would happen on the metal and putting it together after cutting the metal in half would be possible? or not?

[@every1luvsxeno]

nevermind, he answered it later on, should've watched the video first before commenting but my curiosity is bugging me lol

[@prestensualt]

I'm watching this again and i was more than excited to answer

[@gabethemodder778]

How does this polymer react to heat? I'd like to know what chances of it being able to be 3d printed are. With the current methods for fdm (the layer based thermoplastic printing), the layers are often the weakest part of the print. This polymer would allow a part to become more isometric in properties.

[@Bricksniper]

I was just thinking the same thing. This would be a great material for FDM printing assuming its properties are retained after heating. One problem, however, is a different material would be needed for support material I would think.

[@hipjoeroflmto4764]

@@Bricksniper just print things that don't need supports

[@PilkScientist]

@@Bricksniper guys it... it sticks to itself at room temperature... you can just extrude it and it'll fuse. The problem, is that you'd need to put it on a filament roll, when it sticks to itself.

[@Michelino_M5]

That's so cool man, whenever anyone finds a way to make the workings of the extremely small very clearly relate to the workings of objects the size of which we're used to, something just clicks, and it all makes sense. I'm especially referring to the latex + vinegar bit, that's so cool. Thanks for this! Best wishes from Italy

[@adriaanb7371]

Almost like you have a lot of chain lying around 😂

[@FrumiousBandersnatch42]

6:46 when two surfaces of the polymer love each other very much...

[@georgek133]

as a materials science and engineering student i have to say that those explanations are on point and on an academic level too

[@Lishtenbird]

2:08 I think something's wrong with Steve's cheese.

[@ChickennuggetGtag]

lol💀

[@cocobos]

The quality of this video is marvelous!

[@maddog2314]

Seeing that it has a blue tinge to it, I could totally see that as a low concentration of catalyst dispersed throughout the polymer. You could possibly take spectra of the stuff and see the peaks, which would correspond to a metal in a certain bonding pattern. As a chemist, I have the knowledge and the tools to do it.

[@Tangobaldy]

Will my leg reattach in a vacuum

[@SteveMould]

There's only one way to find out

[@Tangobaldy]

@@SteveMould the best reply of the year. Thanks :)

[@thatoneguyJambee]

you made me think of a material that is pretty much conscious and can heal back together because a conscious mind is a mind that tried to keep the body healthy so we have this disturbing reality where we are inflicting pain onto something that that we use

[@littlewyzard]

I’m a materials science major and absolutely fascinated by self-healing materials and considering pursuing research in that area! Thanks for the awesome video!

[@omniverideus]

That was originally "Scotch-70", been used for decades in Aircraft for quick high temperature zone repairs where a good seal is required on something you can wrap. Was very pricey stuff until the recent copies saturated the market.