i recently got this donabe, and i was making a small batch of rice to make into a porridge and seal the thing. i burnt it. i let it soak for about 4 hours and got most of it off but there's still dark black remnants at the bottom. i know donabes are porous so i was wondering if i can even get it out and if it really matters?

i tried boiling it but it started leaking a little bit from the bottom, which i'm guessing is because i never sealed it up.