There’s clean, and then there’s CLEAN. Even if something looks clean, it might still be harboring microbes – many of them harmless, some of them definitely not. With most of the ways that we clean and disinfect — that is, kill germs — the clean doesn’t last as long as you might think.

Disinfectants work by attacking bacterial membranes and viral protein coats, breaking them down so that those germs fall apart and die. But the germaphobes were always right: As soon as a disinfectant dries, and a surface is re-exposed, like if someone touches or (worse) sneezes on it, it needs be disinfected all over again.

The next generation of cleaning products, however, add a trick: they lay down an incredibly thin polymer layer that keeps the germ-killing ingredients in place and effective for 24 hours at a time.