here is how you create seams to weld thin plastic. you can make your own plastic-bags etc with this technique. if you get the knack the results will be air-sealed and water-proof. the process is fast and simple and cheap.
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Step 1: Handy Stuff:
to demonstrate the technique lets keep it basic and just use: a plastic-bag from the trash, a paper-receipt from shopping, a soldering-iron
Step 2: Prep the Plastic
straighten it out over some cutting-board or some cardboard or a newspaper, etc.
Step 3: Use Some Paper:
put it over the edge where you want to create a seam.
(the paper, or alu-foil etc, serves to transfer the heat without actually burning the plastic)
Step 4: A Guide:
here some simple strip from a wooden fruit-crate... use whatever that can take some heat (or go free-style)... ready to trace the soldering-iron along and get a straight clean line
Step 5: Heat
now slowly pass the soldering-iron along the guide and over the paper...
btw, if you are stuck and dont have a s-iron: use any similar metal-object you can heat up over a fire (it works too, just takes a bit more skill and takes a bit longer, since you frequently have to reheat the object)
Step 6: Seam Done, Peel Off the Paper
above you can see a complete seam with paper still on. pull it off, carefully
Step 7: Cut the Leftover Plastic
with scissors etc cut a bit outside the new seam
we are done already.. but i want to add a few steps that show that this technique can be used to make air-seals or bag liquids:
Step 8: Water-test
again, keep in mind that whats shown here just serves to demonstrate the technique.... f.e., lets fill some water in the created bag
.... and seal it off... same process as above
Step 9: Sealed... Done...
thats the finished ´product´
obviously you can customi-make any item of pretty much any size this way.
as always: buy less, work less, play more
thanks you all.