“like onions on a cutting board?” he’d chipped onions many times, the smell lingers even when he scrubbed, “or is it.. More like tomato sauce stains in plastic? Or both?”

“Very similar to all of that,” Carlos said. “We can’t see it, but sometimes the glass gets eroded just a bit so substances get stuck. It’s why we use glass in the first place – it minimizes the stuff that gets left behind. But even glass gets worn and it eventually needs to be replaced.”