How to make really good hard plastic while reusing and recycling plastic bags at home! Via this method, you can make ANYTHING you want to, out of hard, lightweight, real plastic that's astoundingly durable. It comes out very similar in texture to recycled plastic lumber.

best of all, this method involves no fumes!

I'm gonna show you how to make plastic wheels for your robot!

I first heard about stewing plastic bags to make new things from Dave Huebsch's book " Village Assignment " about interesting adventures had while running a charity/NGO (" Common Hope ") in Guatemala. He, amazingly, repaired the bottom weight-carrying main bearing of a washing machine with a big plastic disc made of stewed plastic bags, which actually was such a good stand-in replacement that it held up for several years. (and here are some more Guatemalan Handy Tricks)

I had to try it right away, and the first couple times I just burnt plastic, until I came up with this method.

By the end of this, you'll be able to make yourself a knife sheath, mold around your shoes and make DIY hard-toe sneakers, wheels, bearings, bushings, or any kind of plastic part! Take pictures and post them in the comments!

Step 1: Materials

Collect all the plastic bags you can get, they shrink down a lot.
Shredding them will make your final texture finer.

Use an old pot that you aren't going to use for food any more, or get one secondhand for really cheap at a thrift store.

Find a stick or something else you can use for a spatula.

I liked the clothespin a lot because I could pick things up as well as stir.

Oh, and oil! (I used canola because it was right there next to my stove. If you're, for example, making a bearing you can impregnate it with your personal favorite grease.)

So grab your favorite oil, here's why:

Plastic bags are made of LDPE (low density polyethylene) which melts at 248 F.

I got the temperature wrong and tried doing this in a homemade double boiler filled with water (to regulate the temperature to water's boiling point), which, of course, just made hot plastic bags.

After the double-boiler mistake I re-read the LDPE melt-point and discovered my folly! So I came up with melting them in oil.

Cooking oil boils around 350, which is far too hot for plastic, and which you don't want anyway (splashing boiling oil = no fun unless you're a hun), so I keep it to a nice low-viscosity canola oil heat and things work just fine.

If you wanted a smooth, non-oily finished surface, consider using wax instead.

ALSO: oil is not required per se --
if you had a constant temperature hot surface that you could guarantee to keep down around the melting point, you could do this just fine with no oil or wax!


<p>A student at my institution is doing a project on recycling plastic, and he was heating it in a pot until it caught alight, producing fumes and essentially burning the plastic. I was sure that this is not the way to go about recycling the stuff. This was just a few days ago, and then I received your instructable today :-) I promptly made it in my kitchen, and showed it to the guy. He was utterly impressed :-P Im did not take any pics, unfortunately</p>
<p>I bought a used pyrex casserole dish at goodwill for $2 and melted some milk jugs with a heat gun. when it cools down the block falls out. I read in another instructable that a toaster oven set at 375 works perfect no messy oils. I am waiting for colder weather to give the toaster oven a try. If you press down hard on the melted plastic, it will sick to the glass unitil it cools down</p>
<p>I have no Plastic Smithing experience but need some help/guidance. I'm an ice hockey player that has a permanent wrist injury/condition that makes it extremely difficult for me to hold my hockey stick correctly without pain. I'd like to construct a special custom made ergonomic insert/stick end that will allow me to play without pain. I'm not sure how to go about this (don't know if HDPE would be strong enough?). I found a photo (picture attached) of a hockey end-plug/stick-end that is no longer made or in circulation(off the market for like 10 years)....was thinking I could make something out of plastic that's strong like this (and has a few minor design alterations to suit my needs) - I might be able to start playing some serious hockey once again. Any advice/instructions/suggestions would be highly appreciated. Thank you :)</p>
<p>If I wanted to make something like that I'd just 3d print it. More expensive, but a lot less hassle.</p><p>HDPE is pretty strong. That said, if you wanted to reinforce it you could try melting loose glass fibers into it.</p>
<p>do you know where to get use of a 3D printer?</p>
You might want to mold a folding stock that attached to the stick for a brace for your wrist a twisted cane shape would suffice. I don't recommend burning all this polyethylene real harmful to you and the ozone. Just save poly bags and take back to store
<p>As the guy says in the article, you shouldn't be burning it. There should be no fumes. Your goal is to use low heat to melt it without creating any fumes.</p>
<p>So I had a thought here. What would the results be if you used a toaster oven to heat a pan partially filled with plastic to 250 degrees. Would the results be liquid enough to cast?</p>
<p>Plastic does not melt like metal, it can't cast, instead you force it (inject) into a mold. Or you can spread over a one side mold too.</p>
I don't know about that temperature, but I have seen on YouTube a toaster oven used for this.
<p>I tried melting a block of polyethylene in an oven today. There was a lot of smoke and the outside was starting to brown The polyethylene had softened (and gone transparent) but was not at all melted. There's a chance that the smoke was at least in part from paraffin left over on the tray from the last thing I melted, but that wouldn't explain the browning. Is it normal for the polyethylene to do this? I'm surprised I didn't get any melt at all.... maybe it needed more time, but with the smoke and browning, I didn't want to risk a fire.</p><p>Is the oil how you prevented smoking/browning, aka keeping it away from oxygen? Does it just melt at the bottom of the oil? How do you separate the polyethylene from the oil? Can you just pour it off? My purpose of melting it is to coat some aluminum tube segments. </p><p>I could always try melting it in a microwave (in a glass jar), but I only have one microwave and don't want to ruin it... I tried setting things up to melt it with an acetylene torch outside but couldn't find a lighter that worked, and didn't have the nenn to go to a store and pick up a new one :&THORN;</p>
<p>Just an update... I tried it in a pan on the stove, with a layer of oil over it. First I tried motor oil, thinking that it'd be a lower risk of burning, but it very quickly started giving off a bad smell, so I wiped up what I could and replaced it with cooking oil. I've hit a point where it's not melted, but I'm not comfortable turning up the temperature any more because of the amount of plastic (or residual motor oil?) smelling smoke coming off of it. So again no luck :(</p>
<p>Okay, it gets weirder. Now that it's cooled I could check each individual component. The smell seems to be coming from the plastic, not the oil. The oil just smells like used cooking oil. However, the oil does not *look* like normal used cooking oil, it looks... don't know how to describe it, &quot;partly polymerized&quot;? Like, still fluid, but slightly gelled, or containing some slightly gelled material? Yet it's far too cold for polyethylene.</p><p>Not sure what's going on here....</p>
<p>(might just be that the oil was thick to begin with, I don't know)</p>
Could I get opinions on whether or not my idea will work? <br>-Use an induction cooker to heat a pan filled with HDPE material and a little oil to about 250 degrees. Heat and stir until evenly melted. (I think the induction cooker has the means to maintain a steady temperature.)<br>-Make a wooden mold that uses a 2x4 for a bottom and has wooden sides and ends. Line the mold with parchment paper. <br>-Pour (or drop) the melted HDPE into the mold. Lay a piece of parchment paper on top. <br>-Place another 2x4 on top that's the exact same size as opening on the top of the mold. Clamp the top down and allow to cool. <br><br>This should create a solid block of 2x4 HDPE. The length will be limited by how much HDPE I can melt at one time. I'm hoping I can create 2x4 lumber and build a small bench. <br>
<p>There are mold release waxes that you can apply to your forms.</p>
<p>Strictly speaking, wouldn't the oil be unnecessary (except as a thermometer)? I don't expect it'd ruin anything, though. Wood and parchment paper catch fire at 300F and 400F respectively, so should be no surprises there. </p><p>As for the mold, your plan has you creating essentially a square tube. It could be challenging to make the fit perfectly tight with zero bowing along a void for a full 8' 2x4, but I also don't think a perfect fit would be necessary. I think the bigger potential source of problems would be in lining this tube with parchment paper. Just getting it in would be one challenge; you could possibly wrap the parchment paper around a clean 2x4, insert the lumber and then remove it, leaving only the paper lining. But even then, you would need to arrange the parchment paper in such a way that it can't pop out and stick out into the void; you don't want the paper to get caught on the plastic, folding up <br>and crumpling and pressing marks into your final product.</p><p>I think a safer way to ensure a smooth final product would be to make a mold that opens up along the length of the 2x4, instead of just at the ends. This would make it easier to work with the parchment paper liner: you'd just clamp a flat lid over it all once the mold is full. I admit, though, that such a system wouldn't have as much flexibility to account for varying amounts of plastic. It might be possible to make the mold extendible by building it a bit like a pinewood derby car track: long and shallow, with one of its ends (the &quot;car&quot;) movable so that the void can be lengthened or shortened as needed.</p>
<p>Is there any <strong>risk</strong> in making this? </p>
<p>Ok so how will I know exactly what type of plastic the bags are made of? Is there a symbol to look for or what?</p><p>Thanks :)</p>
<p>Most plastic bags are polyethylene, high-density in the case of lightweight grocery bags, and low-density in the case of heavier department store bags (yes, you read that right...).</p><p><a href="http://recyclingnearyou.com.au/documents/doc-716-plastic-bags-factsheet.pdf" rel="nofollow">http://recyclingnearyou.com.au/documents/doc-716-p...</a></p><p>For other plastics, you probably already recognize the resin identification code, the little number inside the recycling symbol. Wikipedia gives the list:</p><p><a href="https://en.wikipedia.org/wiki/Plastic_recycling#Plastic_identification_code" rel="nofollow">https://en.wikipedia.org/wiki/Plastic_recycling#Pl...</a></p>
<p>Thank you :)</p>
<p>How would you die this material for making lumber. I guess you could make a lumber form and pour/place/pack the material in the form. People have said the material should be pressurized while drying. Guess you could use bricks or something else for this purpose? At any rate, here is a link to making plastic lumber.</p><p>http://www.prosalesmagazine.com/products/decking/how-to-make-plastic-wood_o</p>
<p>to color this material any powder based pigment will work one excellent source i have used was powdered charcoal what i did was i used milk jug plastic than melted the plastic down kneaded in the charcoal into the melted plastic using silicon gloves than clamped it down into a mold the result was a completely uniform black colored piece of plastic that was also uv resistant due to the charcoal</p>
<p>use an oven set to 350, on a cookie sheet with wax paper to melt the plastic.</p>
<p>So, it's been a while since I had a Plastics and Ceramics course. If you process it like this, does the plastic remain High Density Polyethylene, or could some of it be degraded into a lower-grade form?</p>
Video not connected. I'm interested.
<p>I like this. Sweet and Simple, or is it Simple and Sweet ? Not sure. But it looks nifty and I have visions of a homemade kayak in my head. (Might start a little smaller :-) Thanks for sharing!</p>
<p>Here's a video of a different method that uses bottles, seems less messy, and won't require ruining pans.. maybe. https://www.youtube.com/watch?v=kUR6_bQLU-E&amp;ab_channel=PeterBrown</p>
Peter Brown's shop time for the win!!
<p>Would the end product be toxic to animals? I was thinking about making a wading pool for my turtle.</p>
No it should be fine because HDPE is non-toxic in small quantities. That's why the FDA allows milk cartons, water jugs, container lids, and coffee cans to be made with it.
<p>Most supermarket bags are HDPE. Some stores like electronics, clothing etc use LDPE because they are softer and feel more &quot;luxurious&quot; but still all are made out of PE. PE along with PP are considered the safest plastics for food containers (milk bottles, tupperware etc), so it's safe for water also.</p><p>The general idea is identical (except of the absence of pressure) to the one in a plastic recycling factory. Just take care they are clean and better without prints. Colored are just fine as natural.</p><p>If you are still concerned take some glass and silicone and you have the safest result :P</p>
<p>Without industrial controls, there's no certainty of what hydrocarbons or other stuff may be present in the material or produced in the process. You can't know what machine oils, cleaners, inks, etc. were used in making the original product, much less what it's been exposed to since. Imho, I would avoid any use that involves food or water for plants or animals, humans included. Especially if there's heat involved. Though Bpa is falling from use in many plastics, it's still common, and now we're learning that the replacement bisphenols may be just as bad :/</p>
<p>I would not advise it. You cannot use a vinyl pool liner for a fish pond as it contain chemicals to retard algae. Those bags may be coming from many different manufacturers with many different compositions.</p>
<p>thank you</p>
<p>Hmmm, I wonder how this could be implemented into construction</p>
<p>Our municipality (Moreland, Victoria, Australia) has used it for making park benches, car-parking wheelstops and bollards. They worked with a local plastics recycler and are able to accept a much wider range of plastics for recycling - including plastic bags - than most municipalities in the State.</p>
<p>Looks good!<br>Here's a similar Instructable giving a method of making machinists wax by melting plastic bags. Hope this helps somebody!</p><p>http://www.instructables.com/id/Machinable-Wax/</p>
<p>define &quot;lumber&quot; for me?</p>
<p>I use a similar method to melt pieces of mild crate or soft drink crates to pressure mold plastic items . I have built a mini frier using an old kettle element hooked up to a thermostat switch which keeps the hot oil at the right temperature . I cut up pieces of the crate which are quite thick and drop them into the oil . I have my molds standing by which are made out of Pratley putty ,( a two part putty which you mix at a ratio of 1/1 and hardens around the shape of the object being copied . ) . As soon as the plastic reaches a thick treacle consistency ,I picked it up with tongs and drop it into the mold making sure there is enough to overflow the mold so it will fill both halves . Then I clamp the mold together under pressure for a few minutes to force the plastic into both halves to take the shape of the mold . Nice thing about the oil is it acts as a release agent too so the molded item pops out easily . Two issues to take care of though is firstly fire I don't need to warn you about how flammable oil is . Secondly , the molded item has a tendency to &quot; weep&quot; and becomes a bit tacky and has to be washed with a good detergent periodically until it stops . But it is a good way to make small hard to get parts . I make remote control buttons out of hard plastic as the originals tend to wear and become &quot;gummy&quot; with use . Hard plastic will outlast the remote . </p>
<p>any idea how to make a ball for a dog out of the presented methods? ? </p>
<p>you should not freeze it, as that will cause it to fold and wrinkle as it cools and contracts. In fact, you should cool it as slow as possible to give it a chance to crystallize regularly. Also, baking it in an oven works better. Also, you should apply pressure while it is cooling so it will crystalize</p>
could this missed step account for the bounciness?
<p>actually, it should be bouncier if allowed to cool properly. cooling to fast may cause brittleness.</p>
<p>Is there any reason you couldn't stick it in an old cake pan and heat it in an oven? </p>
<p>That's how most seem to do it. They also fold over the soften plastic to give it a marble effect then cool under pressure since this plastic will shrink as it cools ... You'll get rid of most air bubbles as well.</p><p>It also avoids having oil or whatever mixed in with the plastic. HDPE is slippery enough on its own. I certain don't want to play with hot oil, the hot plastic is bad enough to handle - use proper gloves and protection.</p><p>Search Google for some info, YouTube, etc. on the process.</p><p>A good find is <iframe allowfullscreen="" frameborder="0" height="281" src="//www.youtube.com/embed/rpXq6mnbCus" width="500"></iframe></p><p>You basically have to use a non-stick surface, make sure you melt (not burn) the pieces of plastic. Magic temperature seems to be around 350 F (175 C) in oven. Don't use the oven in your kitchen, just to be on safe side (spills, ...) I use a small counter top oven out in garage, just for such work.</p><p>Be safe, have fun.</p>
<p>Excellent video. Thank you so much.</p>
<p>That's my question, also.</p>

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Bio: Hi! I'm Star Simpson! I'm a real me! See more at [http://stars.mit.edu stars.mit.edu]. photo by [http://bea.st ... More »
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