Here is a little cherry wood burl bowl I carved in 2007 based upon an early Native American bowl. I was taken by the abstract quality of the design. Cherry burl can be a very frustrating burl to work with as it is so often riddled with hidden bark inclusions. What appears to be a fine burl at the start is almost always hiding an interior void. But, this is also an opportunity to resolve the problem in the same way Native American Indian carvers did, by filling the void with lead. I consider that these lead patches add to the interest and complexity of the carving.
The middle photo shows how I used masking tape as a dam to prevent the molten lead from running past the void I intended to fill. The top photo shows the lead once it is cooled and ready to be trimmed flush with the surface. I have seen original pieces with lead patches that have been peened into the void, perhaps due to the shrinkage of the wood and the need to tighten the patch.