Using a solar trough-mirror for extrusion

Hi all, I just discovered this precious (plastic) website, so I’m new here. Not in The Gambia though, where I built the prototype of a Solar Food Dryer (SFD) near Kartong. It is located near a stunningly beautiful beach, where ~sadly, like on any other beach~ 90% of all the rubble that washes ashore is some kind of plastic. I’m planning on this low-tech part-solution: using a solar trough-mirror to heat a pipe through which plastic should be extruded into rough poles or sticks that can then be used for fencing land.
Some questions:
– What will happen if I do NOT wash and clean the plastics in ‘clean’ water, but wash have them washed in seawater only?
– What will happen if I would NOT separate and select the different types of plastic and shred them randomly, all kinds mixed?
These two conditions would allow for anyone to collect any plastics on the beach, wash it there and sell it to me. Sweet water is costly.
Anyone with any experience in this area to offer some advice?


Great plan! I was recently in Ghana at the beach, dirty place!

The effects of not washing totally depends on what kind of dirt is on the plastic, in general it will still melt. However it probably won’t be as smooth or consistent and you can see the dirt in the plastic. Honestly I have no idea what kind of effect the sea/salt will have on the plastic, definitely worth a try! Very curious to this outcome

Different types of plastic have different melting temperatures. So if you want to progress or melt a mixture you will end up with not all the plastic molten, or if you fire op the temperature some plastic will get burned. To be honest you could still make something out of it that looks good. But the biggest downside would be that you make something which isn’t a pure material. Which again makes it more difficult to recycle in the future.

That was just an average beach, no recycling going on. It really is that bad…
I think you definitely need to have some sort of basic separation. There are some clever ways to deal with this, like putting shredder plastic in the water, some types will sink others float giving you some sort of separation. Yes, clean beaches is a great improvement. But if you can find a proper way to also separate the materials properly it’s an amazing improvement!

Don’t know if you can regulate it on that way. Interesting approach though! However for things like extruding 3D printer filament you need a very consistent output, so it might not be suited for all applications.
Nylon, dunno, haven’t tested it yet…

Thanks Dave, I assume your Ghaneian beach picture shows the result of collecting plastic for reuse / recycling? It can’t REALLY be thát bad… Not with us in Kartong I’m happy to say.
Especially your last remark gave me some second thoughts. And with melting T’s as wide apart as 120° and 260° I may be obliged to have a minimum degree of separation anyway. But then again: if my imperfect recycling would result in a clean stretch of beach for years to come and fencing poles that would last a hundred years, I think that would still be an improvement, wouldn’t it?
On a different note: would you agree that the T in the trough-pipe could be regulated by the throughput or conduit? (I mean: by the amount of relatively cool shredded plastic to be pushed through the pipe.) I’ll have to experiment with different diameters as well. And I’ll need an adjustable motor driving the supply-screw-pump. (what’stheword…)
And by the way: what about nylon? I find a lot of fishing net and thick ships-rope on our beach. What type of plastic is that actually?