Malc2098 wrote:How does spalted beech, or is it birch, behave under a plane or chisel?
I can only say how it behaves under the turning tools, but this also depends on how far the wood has spalted as sometimes it can be rather punky and will tear out as soon as the tool starts to cut.
If you keep the tools as sharp as possible then with the majority of it you will get a good finish. Something also to take into consideration is that when turning something like a bowl that most times you are cutting not only with the grain but against it as well all in the same cut and this can cause problems of tear out.
As you can see tear out is the biggest problem so gentle/light cuts with sharp tools is the answer and even this it does not guarantee a good finish, as turners one thing that can be done is to try and stabilise the wood by coating it with sander sealer but that only will deal with the top layer. Sanding can also lead to an uneven surface.