By silk, I'm pretty sure I know what you mean, not thinking it's real silk, but also not the old cloth covered cords
in this last month with all the machine I just bought is a cord like that. it look very close to new. I plan on not using it daily, but only to keep it nice and clean
butt the down side of these old cords is what you can't see, under the fabric the wire is still coated / cover with natural rubber. the natural rubber is what breaks down, then crumbles
rather than get into a long drawn out story about rubber type insulation.
you question the cord or you wouldn't ask the question.. for your own security just get or make a modern cord