If a ribbon has half its curls one way, and half the other, its total twist is zero. I suspect that if you scrape a ribbon with a blade (thus making it want to

If a ribbon has half its curls one way, and half the other, its total twist is zero. I suspect that if you scrape a ribbon with a blade (thus making it want to curl up), hold its endpoints, and bring your hands together, it will settle into such a configuration.