People use pinking shears on the edges of raw fabric as a way to finish the seam and prevent fraying like a straight cut would get.
But I can’t get my head around how/why exactly the zig zag edge makes it less likely to fray. If anything I’d think the little triangle points would be easier to fray.
In: Engineering
Do you know about how cutting on the bias virtually eliminates fraying? It’s cutting on the bias in opposite directions one after another so there are never straight cuts!
>If anything I’d think the little triangle points would be easier to fray.
Sort of. It’s slightly easier for micro-frays to start, but they can’t spread.
The edge of a piece of fabric looks sort of like ±±±±±±±±±±±±±±±. If something snags that upper ––––––––––––––––––– thread, there’s hardly any weaving to hold it in place, so it can pull *all* the way out; then the _ _ _ _ _ _ _ _ _ _ _ thread shown is exposed, and something can snag *it* in turn, and pull it out.
(ELI5’s rule about explanations having to be text in the comment is dumb.)
When the edge is pinked, only the very tips of the zig-zag edge are vulnerable: the threads exposed along the edge of the cuts are still woven in over-under-over-under at least a few turns; there’s enough friction to hold them in place.
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