Since you don't have a pot large enough to boil it, you could always use some type of clean plastic container. Boil a few pots of water after rinsing the wood off outside and pour them over the wood into the container. After the container is full and the wood is submerged, let it rest over night, then dump it out and repeat the following day. Do this over and over again until you are happy with the cleanliness of the wood and the clarity of the water.
I'm sure hot water could be substituted for the boiling water after a few days, if you are just trying to remove more tannins.
I'm sure hot water could be substituted for the boiling water after a few days, if you are just trying to remove more tannins.
