Soda Bottles Used as Heat-Shrink for Wood Joinery

Nobody is likely to confuse it with the beautiful joinery that makes fine furniture so desirable. But as a practical technique, using plastic bottles as heat-shrink tubing for composite joints is pretty nifty, and the pieces produced are not without their charm.

Undertaken as an art project to show people what can be done with recycled materials, [Micaella Pedros]’ project isn’t a hack per se. She started with bottles collected around London and experimented with ways to use them in furniture. The plastic used in soda and water bottles, polyethylene terephthalate (PET), turns out to shrink quite a bit when heated. Rings cut from bottles act much like large pieces of heat-shrink tubing, but with more longitudinal shrinkage and much more rigidity. That makes for a great structural component, and [Micaella] explored several ways to leverage the material to join wood. Notches and ridges help the plastic grip smoother pieces of wood, and of course the correct size bottle needs to be used. But the joints are remarkably strong – witness the classic leaning-back-in-a-chair test in the video below.

Its aesthetic value aside, this is a good technique to file away for more practical applications. Of course, there are plenty of ways to recycle soda bottles, including turning them into cordage or even using them as light-pipes to brighten a dark room.

Thanks to [infrared411] for the tip.

81 thoughts on “Soda Bottles Used as Heat-Shrink for Wood Joinery

  1. We tried that a couple of years ago. Maybe OK for indoor use with artificial lighting – but as soon as you get UV on the “joints”, it’s only short-term fun.

    1. Kevlar is damaged strongly by UV… good thing they never use it for anything important.

      If only there was some kind of coating that came in a can, that was liquid, and you could apply it to objects by wetting them with it, and then it would dry, and it could reflect any color, so you could change the color, or it could reflect all the colors so it would be a brilliant white and absorb barely any radiation… we could come up with a placeholder word until such a thing exists, like thingcoatandprotectingstuff …

      However although PET is not reckoned to be UV stable…. I don’t even remember having a problem with it in my numerous container re-purposings… margarine tubs yes, go brittle in a couple of years, PET bottles… if I really looked, I could probably find you a 15 year old one…

          1. It’s not the leaking, it’s the thing that when you open them and try to pour it’s like holding a bag and the pressure of holding it squeezes the content and makes handling cumbersome and you have to carefully hold it with two hands. So idiotic.

    2. Given that used PET bottles sometimes remain in the environment quite long, longer than wanted in case of waste, it seems to be quite UV stable. I just wonder, if the deep slits necessary for this kind of joint are the best idea.
      Polyethylene bags get brittle much faster.

      1. Some of that has got to be that PET is UV transparent, the more it lets through, the less is energetically absorbed effecting chemical change.

        Other plastics are opaque to it absorb UV and degrade faster.

        The other option is reflecting it, but things that do that well tend to be metallic, aluminum powder, zinc oxide, titanium dioxide etc.

        1. PET is definitely *not* UV transparent. The T in PET stands for “terephthalate”, which is a benzene ring with a couple of substituents attached. Benzene = UV absorption. PET, specifically, absorbs pretty much everything at λ ≤ 320 nm.

          1. Given that it might be presumed that we’re talking about Earth normal environmental conditions, near sea level, then the highest proportion of UV in sunlight, 96.5% is UV-A, and it passes most UV-A.

            You are 100% correct that it starts to block in the UV-B region, in the same sense you would be correct if you said “On average, airplanes can’t fly.” … because on average the Universe is a vacuum.

            You win today’s “Technically correct yet missing the entire point and context of the situation.” Award for excellence in exacting but valueless pedantry.

  2. Hmmm. wonder just how hot it needs to get? I can see cutting the top off of one of those extremely thin water bottles, sliding a pcb in there and ending with a fairly weather resistant conformal container.

    Also, how about putting some epoxy or other filler/glue on the joint before shrinking……

      1. Nearly boiling water will do the trick. Full disclosure: I’ve used a plastic bottle in an old sock as a makeshift hot water bottle. Worked like a charm but at first sight the shrinkage was alarming!

          1. If I want to drink the water I would fear that heating it in the bottle could leach some stuff out of it. But in an emergency situation when you are in dear need of a cup tea…. :-)

  3. Honestly it is mind blowing that so many places dont have bottle deposits to make sure the stuff is recycled. when I moved to Florida it was obvious they need it as you see soda bottles and beer cans all over the place as random trash in the rivers and even roadways.

    1. Come up to Michigan then. About 95% return rate on all bottles that has bubbles in it. Non-fizzy drink which includes bottled water still do not have deposit and still gets wasted rather than recycled.

      1. When fishing and you pull up a sucker you say “muck fishagain”! I thought that their this-can-cannot-be-crushed-or-deformed to recycle was bad enough. I call a can crusher a Muck Fishagain machine. This really wins the booby prize. Same bottle different claim. The healthier choices are not honored just fattening sugar slop.

        The worst problem is with fast food drinks, the foam cup plastic lid and straw trio found in probability distribution around those foreign owned “convenience” stores allover town.

          1. our cans have deposit too, not saying there is no litter or that there is never a bottle or can anywhere at all, but they aren’t a common sight, excepting early saturday and sunday mornings when people have left their cant and bottles form the night before, they are usually gone by noon, considering one can easily make 50usd collecting cans and bottles in a few hours that really isn’t that surprising.

            there is even temporary bottle racks on some bins so people don’t have to root through the bins for them.

  4. So, PET is a close relative of the PETG 3D printer filament that’s all the rage these days. Among the advantages of PETG over ABS is the low warping factor, which I see attributed to dimensional stability with temperature. These PET bottles shrink when heated, though. What’s the deal?

    Is it because the bottles are blow-molded or something and the polymer chains get locked in a streched-out state when they cool? Then re-heating them unfreezes the state?

  5. Very “slum chic”. That idea is worth exploring further, e.g. how many layers of bottle can you build up by shrinking one over the other, and what are the mechanical properties of the result?

    1. You get a rock made of plastic. Hard, medium high density. You will make several of these just by not watching the time while heating plastic for your latest project.

      If you alternate the colors of the layers you can carve it back down with a dremel and make some pretty impressive sci-fi flowers. Don’t ask me how I know…

      This is an old arts and crafts technique I’m glad to see get some new airtime. They become impressive if you have artistic skills such as I lack (Thank you Mom!). So much plastic around now that it is very well worth your time to experiment a bit. Milk jugs, bleach bottles, vinegar bottles, soda bottle…

      Is worth a few evenings of experimenting by any hacker for making a small enclosure in any shape imaginable. Works fine with just a vacuum cleaner for encasing small electronics needing weatherproofing such as gadgets to add to your motorcycle. Works ok with oven or just a hot air gun.

    2. What if….

      You cut a book sized piece of wood, rounded all the corners nicely, contoured it to a pleasing shape.

      Then got a pile of large bottles, and sleeved it in alternate directions several times. They’d probably want to be chemically clean.. multiple layers.

      THEN.. you cut around it with a dremel, and pulled it away from teh wood…

      Do you now have a sweet case for your Rpi laptop???

        1. Unfortunately, just realised that I don’t think they’re going to stick together without some further step/process/component . Reason is, we’re playing with plastic memory effect and glass transition temperature at temperatures somewhat blow true melting point, so layers will not fuse. If it is raised to near true melting point then the polymer chains are free to move against it’s other and it’s lost all the tension, be like something you just dipped in plasti-dip or something. So in order to create a solid piece, needs solvent for surface bonding or a glue or cement.

      1. Ahem, no, it’s quite thermally stable. They actually make PET baking sleeves. This being your second ill-informed comment on the current topic, I have to ask: do you even know what you’re talking about?

        1. Do you? This looks like second time unlucky…

          First you seem to have strawmanned my meaning as “OMG it assplodes at super low temperatures.” Which is not what I said. Secondly, I was of course referring to previously used PET, not virgin, which has endured some thermal oxidative damage in original processing, has been slowly accumulating more during it’s shelf life and use, and reheating it above melt point, which is 250C will be causing more degradation the longer it’s maintained near there. Especially if it has not undergone a low temperature dessication process to remove absorbed water. So while it’s virgin breakdown temperature is 300C it’s deterioration after exposure to “life” is accelerated over 250C. Since you’re likely to be doing this without a set point heat source, and just trying to guesstimate the distance of “hot enough” from a heat gun on high, or an electric heater or similar, which if it’s element is glowing orange is probably near 1000C then yah, relatively “few” degrees between where you’re melting it and damaging it.

  6. I read this article in an email sans pictures and thought that’s wonderful someone is using an art instalation for a purpose. Then I open the page and see the images – my enthusiasm was shattered by the appearance of the end product.

    If someone was dubious of the possibilities of heat shrunk plastic bottles and there fears would be confirmed by the awful presentation.

    Recycling is great but does it have to look like your in hobos abode.

    1. I think you might be one of the trolls who likes to yell fake on stuff and are put out that when someone showcases a method, they make it bleeding obvious how it’s done.

      1. No I don’t think I’ve called fake on anything.

        Show case an idea and call it an idea – don’t show case an idea and call it art.

        The above posted video sayes it all.

  7. Art students are funny. And while the attempt at “recycling ” or efficiently repurposing a material has been made, the result and accuracy of both attempts are sadly as close to reaching an accord as a train horn would come to toning lead in a harmonic concerto.

    Usually there are engineering colleges or branches of the attended university near by the art building. These colleges specifically deal with developing and implementing the technical and industriously complex make up of inorganic materials and their lifecycle duty so to minimize its negative impact to life on earth and earth itself.

    There is something internal to all man made things, and it is as important to that thing as our lungs, hearts, and blood are to our existence. The call it “embodied energy”. Simply put it is the energy that was required to make the item. Energy spent in actions such as, any process part of the extraction of oil required to produce polymers, the energy consumed by all the alarm clocks that wake the people who work to produce the plastic; the engineers, production line workers, the facility administrators, the logistical team who burn more fossil fuels to get the raw, developed, and implemented material to where it needs to go, and so on. The point being,

    While I’m certain it was not intentional that this project strayed so far from its target of “showing what people can do with ‘recycled’ materials”, it nonetheless did so with a graceful and blissful ignorance. What is defined as recycling here would be better defined as, removal of a material from a system which it was intentionally designed and developed to stay within so the consumption of more energy wouldn’t be required to replace its volume as part of an enclosed system, or what is intended to be an enclosed system, should it be handled with responsibility, care, and intelligence by its care takers… You and I.

    So when you see plastics laying around, please get them to a plastic recycling bin, so they don’t end up in a dumpster behind the art school before they plop down for the long haul in our waterways and water bodies. If you need to build some tables that require fasteners, and you don’t have the money to buy those fasteners, go out and about, locate and recover 5 plastic bottles that have been discarded incorrectly, take them to a recycling facility and get the 25-50 cents their worth. Then take that change and head to a local hardware store where you can purchase penny nails to use to fasten your wooden parts together.

    While plastic bottles are a plaque on humanity, earth and the life it contains, it is truly one of the few materials made by man that have been designed, engineered and manufactured TO BE RECYCLED! To stay contained within the system to which they were intended. Trust me when I say, the percentage of loss per trip thru the recycling process has been accounted for. Let’s work to keep that loss to a minimum, move humanity forward, and maintain a thoughtful progression to your life, the life of the earth, and the lives of those you share this ONE home with.

    1. Nah…

      We’re not talking about infinitely recyclable glass here. Only 7% of those recycled ever end up as bottles again, the largest proportion ends up in “make work” products, as in here’s a lousy yet strangely expensive product made from recycled bottles so you can feel good.

  8. I wanna try some stuff with this… make structures, tall poles, bendy poles, arches… bamboo sticks laid 4 into 4… use spacers, jar lids maybe, space them out, 6 into 6 or 8 into 8, overlapped, spacer each side. Make poles out of Monster cans. Make freaking rafts out of Monster cans, walls, stick fences.

    Many times I see odd sticks of things and want to assemble them cheap into structure, use as a material. Surplus stores, with shit like “carbon fibre rod, 1000mm” 10 cents a piece or something.

    Shrink wrap your bike rack onto your hitch so it doesn’t rattle (still use pin of course)

    Heck, wrap handles of any tools that are getting rough.

    Wonder if you can seam or spot weld pieces of it, without shrinking it much, to make bigger/custom stuff…. think of topology of briefs or something.

  9. How about if you cut the bottle in a spiral to make “twine”. Use the twine to make a lashing and then hit it with a heat gun. This should make your lashings tighter than you can achieve by hand.

    1. Yeah, I was wondering about methods to do custom shapes… Might be hard to stop the ends slipping.

      Though also, if you’re talking about a square lashing, you could do it through a ring of the stuff with conventional cordage and have it tighten around it.

  10. Faygo 3L bottles are the biggest “pop” bottles I know of. Then there’s 10L 2.5 gallon and up springwater jugs… What’s other “big stuff” is out there?

    Also at the other end, what’s the skinnier stuff, I guess tall 330ml water bottles is all I can think of, seems little too big for pencils say.

    1. 3L soda is the largest I have seen. Maybe strips could be cut so they lap together into a larger ‘ring’.

      The smallest… cheap long bubble-wand tubes from the toy section of Walmart.

      1. Thx for the bubble wand tip…

        Looking around the house, found a couple of small pump squirt bottles that were PET, then there’s also some narrower shampoo bottles and cosmetic bottles. I’m thinking “travel size” products might be a good source of the little ones, and hotel courtesy products.

        I’ve also found some PET vitamin bottles, but they are hard/thick, so I don’t know if they’ve had so much expansion ratio, and therefore may not contract much.

        Who number 1? PET number 1! :-D

        1. Between the vitamin bottles in thickness/hardness and the travel size toiletries, there’s herb and spice containers. Again, hard to know how much they are stretched and thus will shrink.

          Mylar is highly stretched version of PET, BoPET, used for chip bags etc… high shrinkage ratio, but a thin material in the first place so kinda light on the mechanical support. Also typically multilayered in packaging applications, so you probably won’t get interlayer adhesion if multiples used.

  11. For permanent jointing, I don’t like it, issues with UV degradation, friction, etc. But as a temporary binding it’s brilliant and I’m ashamed I’ve never thought of it. As a strong “shrink wrap” to bind parts together during the build process, this has great potential.

    1. Good idea.

      I progressed into thinking about it for “temporary” binding/clamping for things. Like scarfing together 2 2x4s, apply decent glue, like a resin type, clamp with bottle, leave for few days to really set up hard. Depending on application, you might as well leave PET on there unless it’s in the way.

  12. I used this method to protect my outdoor kitchen, which has wooden legs, from rotting away too soon. I Used a blow torch to shrink the PET bottle. But that is quite a tricky way, it’s very easy to melt a hole in it.

  13. I have used silicon with heat shrink to seal a joint.

    Both the curing and non curing seem to work quiet well. The excess just squeezes out as the heat shrink shrinks.

    Hot melt glue could be pre applied and allowed to set then reformed when the heat is applied.

  14. I saw how they them used in poorer countries to make artificial limbs for people who lost a leg, they shrunk several bottles over each other to make it strong and by using a mold it’ll conform to the stump.
    Many magnitudes cheaper than the real thing and thus available when the real thing isn’t.

    There’s probably an old HaD article on it.

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