That’s a brilliant piece of science, but on the off chance you’re serious, it’s because a fart is a gas but the Covid travels in droplets of water that will be absorbed by the mask. It’s more like when you wet your pants the wet stays absorbed on the pants rather than all over the floor.
Thank you. A rare voice of reason.
“it’s because a fart is a gas”
It also contains vapor as does your breath which gets through cloth.