According to Leviticus 19:19: “…Thou shalt not… wear a garment upon you of two kinds of material mixed together.” This Old Testament law may not carry any religious weight today, but that doesn’t mean there can’t be consequences by ignoring it.
According to an article in the December 16 issue of the Washington Post, the paper used for printing American currency was fabricated from a blend of cotton fibres salvaged from recycled garments, especially denim. However, in the 1990s denim began to be tainted by the addition of spandex (aka lycra.) This stretchy material had been in use for girdles since the early 1960s, and bicycle shorts since the early 1980s. In the 1990s, blue jean manufacturers discovered that blending a bit of spandex with denim created better-fitting jeans.
However, as much as spandex benefitted blue jeans, it weakened the dollar. A batch of currency paper could be ruined by the inclusion of spandex fibres and there is no practicable process for separating spandex from cotton fibres. Crane, the company that has been making American currency paper for over a century, had no choice but to buy new cotton instead of recycling used garments, which explains why thrift stores are now inundated with racks of blue jeans.