Plastic washingdrying

Finding big problems lately now that rainy season has started here on the tropical island.


HDPE is supplied dirty/wet.


Used clothes washing  machines are fairly cheap where I live, clothes dryers not so much cheap but available.


I have seen someone  using  a drum made from a discarded washing machine for washing plastic.


If for example, bottle caps were washed in a washing machine and then placed in a cloth/mesh bag and run thru a dryer…  would this be viable?  Has anyone here experimented with this this yet?




Hi Bmetz,

Tropical Darwin here, we share some challenges including humidity messing with filaments etc. Darwin Plastic Makers Space is just about ready to start work in their space and are planning exactly what you describe – a recycled washing machine and tumble dryer.

The waste water which is likely to contain small plastic particles will go to a settling tank with a fliter (stage one) and then will be pumped through another filter before being used again as pre rinse (before washing) or to water small trees we are planting and gifting to help offset our carbon footprint.

Just throwing out their an idea floating around in my head (i’m currently keeping an eye out for another free washing machine to turn up at the local tip), has anyone considered/tried attaching a few blades for example lawn mower blades to the center of the tub to both help create extra turbulence and to a lesser degree cut larger items (like milk bottles) to allow for better pre shred cleaning.

The aim wouldn’t be to shred in the machine, just to cut larger things open to allow the insides to be cleaned better without needing to manually cut each bottle.

In my mind I am thinking maybe 6 blades, two evenly spaced off to one side, at 90 degrees to that a single blade centred and angled opposite and then repeat 2 blades then one each 90 degrees.

Might be a terrible idea, might be a winner but I figured until I can get hold of a machine to test with it isn’t fair keeping it locked in my head.

Added an image for the visual thinkers.

the washing machine experiment is a success. I filled the machine with aprox 7 kilos of bottle caps, added in a bit of bleach and ran the machine.


It came out nice.  With the spin cycle there was not much water left and it dried fast.  I then shredded it.


The washed plastic comes out much better than the unwashed from the extruder.  no pops, steam, or smoke unlike the dirty plastic that has a lot of contamination.


It also smells better.


Locally I found new washing machines for 80usd without an agitator or spin basket.  there are separate laundry spin baskets for sale locally that are fairly low cost.

Hey @juul! Not quite sure what you’re end goal is with the buckets and what you’re thinking of to rotate them… but when I saw this picture I automatically thought of the big manual salad spinners we use to dry lettuce greens on the farm…

@s2019 this trailer would be attached to a bike. So when you would cycle home after a clean up your plastic is ready to be shredded. Yes, true this is also a nice option!

@juul I’m not sure what you mean by cycling, but one option would be to make a larger version of a rotary rock tumbler. If you take one of your blue, upcycled food barrels that you have a sealing lid for, add some inside paddles (just some angle or equivalent), and lay it on a pair of rollers, you can drive one of the rollers with a stationary bike.

, since you are in a sunny, hot place, I wonder if making a simple solar hot air collector out of sheet metal, aluminum cans, etc. and blowing that through your wet caps would help with the drying without needing extra machinery.

I’m working on a little washing-cycling tool that could help you with washing on a small scale. After a cleanup, I will fill up the crate with water and some natural soap. By cycling, this should start spinning the buckets around.

At the moment I am trying to figure out how to get the energy in the right direction to be able to use the speed of the bike to turn the crates inside the container. This will all depend on how I will connect the wheels to the buckets. Any suggestions are welcome 🙂