double fold

Illustration with arrows depicting the act of folding along a crease in two opposite directions.An illustration of how to do a double fold. By Nilsjohan, public domain, via Wikimedia Commons, https://commons.wikimedia.org/?curid=11805173 n. a crease made by folding one side of a material onto itself and then back along the same crease in the opposite direction so that opposite sides touch

Notes

The double fold is used in testing the endurance of materials, most often paper but also sometimes film.