I turned this bowl from unseasoned London plane. It warped to an oval shape as it dried. It has a dark stain at the rim, caused by metal in the log. One never knows what is inside the timber – in this case it was a large iron spike, hammered into the tree long ago. As the tree grows, the foreign object becomes enclosed and hidden. Sometimes staining shows the presence of metal, but my saw found this spike, which will not be included with the bowl. I shall keep it to remind me to use a metal detector in future.