[ His chanting doesn't slow down or miss a beat, keeping pace until absolutely everything's back up, seeping into the ground beneath Emet to immediately stain. ]

Water.

[ He orders to the onlookers without turning to face them, though with his tone much calmer perhaps the worst of it all's passed. He'll give Emet a helpful push away from the stain he's just made so he isn't going to be marinating in it while already ink-stained fingers are retrieving the onmyoji's brush. ]

Normally I would say the residual pain from such a taint would last over a week.

[ A dip of the brush into the ink, and Seimei's drawing characters across the newly tainted ground. ]

Considering you could hold that much inside you for that long and still speak, however, I'm admittedly uncertain how long you will need to recover.