India cushion filling material out of bottles

Hi there!

I am new to the community, but have had the precious plastic idea in my mind for a few months. I am currently residing in India and was looking for a way to integrate environmental and social issues into a cool project.

I was also meditating a bit in different medition centers, typically on too lumpy, too hard or too soft medition cushions. The best ones proved to be the ones with a loose filling like buckwheat hulls or millet seeds – but they are expensive, and especially the buckwheat hulls compact with time and you need to top up the cushion with some more filling material.

So I was thinking if I could use shredded plastic as a filling material, basically creating the “raw material” like most of you guys do before you use it in further extruding processses etc…
But there were some open questions that I hoped you were able to help me with some input:

  1. Shape and sharpness: Will the edges be very sharp after the shredding process? The particles will need to be small, I would say no bigger than 5x5mm. What does it feel like when you run your raw materials through your fingers? Does it give you cuts if you compress it in your fist?
    I was considering thick linen as an inner cushion cover, but I am not sure if it would hold up over time. If not, how could I get the particles softer – possible put them in a concrete mixer with rocks or sand, like you do with glass shards?
    Buckwheat hulls are also quite prickly by itself, so I don’t think that it would be an issue sitting on slightly sharp edges of plastic through two layers of thick fabric – what do you think?

  2. Form: Does shredding waterbottles down to 5x5mm produce mostly flat pieces or will there also be a lot of convex ones from the bent parts of the bottle? Do you think that plastic shreds would compress a lot over time, so that the cushions would loose their shape?

  3. Cleaning: I thought accepting only clean water bottles as raw material would be best since they are reasonably clean and uniform. I am still worried about smells etc., and I don’t want to use either huge amounts of scarce water to clean or powerful cleaning agents in regions where there is no wasterwater treatment whatsoever. What do you think about this issue? How do you clean you raw material before you use it in further processes? How can I reduce the water intake? Does it start smelling after a while?

  4. Smells of plastic: stupid question I guess, but will foodsafe materials like from waterbottles diffuse out plasticizers over time? I presume that the clientel for this kind of product might be very sensitive in that regard, so I really want to be sure….

  5. Sounds: so I am not intending to use plastic shreds as filling for sleeping pillows, but meditation rooms tend to be very silent as well – when you shift the raw material around, does that sound very loud and plasticy (jezz, I hope you have any idea what I am talking about ^^ – as in like bending plastic pieces, or the clicking sound of water bottles that contract after you filled in hot water and cool down for example), or is it more uniform sound like grains being moved around? I don’t think it would be a complete dealbreaker if there was some noise – the buckwheat hull cushions also make a little sound when you move around, but it shouldn’t sound like you are crunching up a plastic back.

So the whole question I guess is if you think that is in any way a feasible thing? Anyone with raw material at hand willing to do a “sitting test” 🙂 ? The alternative would be to do the whole process, with extruding and cutting into pellets, but of course that would be a lot more difficult to implement than simply using the shredded raw material straight away.

Then I was thinking also about operating it with physical labor instead of electrical power because power outages are so frequent here – I have seen a bunch of “entrepreneurs” here that refitted a bike into a knife-sharpening business with flywheel and all, and read the tread on that here. But before I go into further details, I am thrilled to hear what you think!

Cheers, iane


Hi Iane,
Nice idea! I can answer some of your questions:

  1. Shredded material is not really sharp. It will not give you cuts.
    We keep the shredded material in thick plastic bags and it does not tear them apart

  2. It will be mostly flat parts. Because of the low thickness of the material the convex parts will be pressed to flat parts. The material itself does not compress by itself. With shredded material there is a lot of air in between the parts. Make sure to stuff the cushions with a lot of material.

  3. Normally we do not really clean the stuff we get. (we get a lot of clean plastic) Also we do not use PET bottles because of exact temperatures were PET melts.
    Cut some bottles apart and let it dry in the sun. You will find out if it starts to smell.

4)PET can diffuse additives over time (leeching it is called) but I do not think it will start to smell.

  1. It makes some noise but within good cushioning I think it is reasonable. You should test it by yourself to see if you think it is reasonable.

I think overall it is a feasible project. But, you need a lot of bottles 🙂

hope I helped you out a bit.
Next week I can sit on some of our bags with plastic to see how it sits (only it is not PET but material with sizes like 3X3X3mm.

And what about using PET strings? PET STRING MAKING

Have a look on this link

I’m pretty sure that it could be possible

We use mostly the plastic type’s pp hdpe and ps. We have a contract with a pawnshop and they send us the stuff they cant sell. Video cd and dvd boxes, lot of toys, plates, containers etc. It has all a bit more wall thickness. So the shredded material is more cube than the, thin walled, shredded bottles. I do not know if it influences a lot, maybe the sound.

I think the additives are not a big issue. Because they will be protected from weather and sun. Although you dont melt the plastics. Keep it all one type. Once the types are mixed it is hard to separate and then hard to recycle.

About the research: I learned from my study it is hard to convince people to use recycled or even environmental friendly products. People tend to think it will be less good as new materials. So in my eyes it is not surprising people are not really interested in it now. I think when you can prove it works (with prototypes) people will be more interested.

The cotton candy machine sounds like a really cool test. Although I think it will not work because plastic is different then sugar.


Perhaps something like a cotton candy machine Could make wadding ?

Dear Mathijs,

thanks so much for this elaborate reply!

Happy to hear that overall you seem to think it is feasible, this gives me hope to proceed further with the idea.

I am currently doing some “market research”, asking people if they would buy a cushion filled with recycled material, and while the reactions are not exacltly all stellar, I think it could work. Obviously I need to read up more on all the additives and stuff that are used in the production of the bottles and how that could react over a longer time.

Regarding your answers 1), 2) and 5): what rawmaterial are you using, and is there any reason to believe that PET would differ greatly from this?

I will go ahead and do some tests armed with scissors and some elbow grease and see if I can find out more about the properties relevant to odor and seating comfort that way ;).

Finding sufficient raw material here is really not difficult at all :confused:

That link you added might also be a good alternative for the start to get flakes (by cutting the strings in smaller snippets) without having to invest in a shredder yet, thanks for that idea! I find this really helpful!

If anyone else has any further input, thoughts, experience or ideas, they are highly welcome!