2. Fix fabric dye.
Remember how you used to tie-dye white t-shirts at camp? Nowadays, tie-dye kits use special chemicals, but in the past, plant-based dyes were fixed into the fabric using a mordant so the dye wouldn’t run. Because of its high level of ammonia, one of the most popular mordants was stale urine. Families would leave chamber pots out to collect urine for dyeing. At one point the demand for urine in 16th-century England was so high that textile-manufacturing towns, like those along the Yorkshire Coast, would import it from big cities like London and Newcastle.