When in doubt, don't use. I got two big driftwoods from my friend's place and spent countless hours removing some burnt parts, some bark left, I boiled it, I put it in a large drum to release toxins, I weighed it down...just so much time and effort, in the end, it was still leeaching and wouldn't sink.
I just ditched it, went to my LFS and bought a much more beautiful one $25, when I put it into my pond, it sank and released no toxins...best $25 I've spent! There are pictures of it in my thread.
DIY other things, when it comes to driftwood, just spend your money.
