There’s more than one way of upcycling plastic bags into plarn (also known as plastic yarn). The most common method involves flattening the bag out, folding one side to the other side one inch at a time, then clipping off the top and bottom of the bag so that you’re left with a cylinder shape (still folded up). Then you clip the cylinder into 1/2-inch-wide loops. Finally, each loop is tied on to the next, which effectively turns the bag into a double string of plastic yarn with frequent knots in it.
If you’d like your plarn to turn out a little smoother, shake the cylinder open instead of clipping it into strips. Starting at a random point on one of the open sides, cut the cylinder into one long, continuous inch-wide spiral strip. Knot the strip cut from one bag to the strip from the next bag, and so on. You get a single strip that’s about equal in thickness to the one generated by the method above, and the knots are much less frequent.
Although the number of knots in your plarn creation will affect the look of the finished product somewhat, you can use either type of plarn for any plarn pattern. We've supplied a link to one of the best repositories for plarn patterns at the bottom of this article, but your own collection of knitting and crochet patterns is the best place to start looking. In general, patterns written for worsted weight yarn can be knit or crocheted with a single strand of plarn.