I'm not sure if this is the proper forum for this question but a moderator can move it if necessary with my apologies. A few years ago, I picked up several pieces of live edge black walnut from a local retired farmer. If I remember the story correctly, his son worked at a mill or had a small mill of his own or something like that. Anyway, the wood was nice and it was very cheap. Most of it was used for a variety of small projects like cutting and serving boards. I have two pieces I set aside for a bench or table but they have become significantly bowed over time. I can only assume they weren't fully dried or perhaps I didn't store them properly (they were in an unheated garage for a few years). They're about 40 inches long, 7 inches wide, an inch thick and still have the bark attached. If laid with both ends on a flat surface, the bow in the middle of one board is almost an inch from the surface and the other is about a half an inch. Last summer, just out of curiosity, I put some wet shop towels between them with the concavities facing, clamped them together until they squeezed shut and set them in the sun for a few days. When I unclamped them, they were a lot closer to flat; not perfect obviously but enough to work with. However, since then, the bow has returned.
Are these boards pretty much done for except for small projects? I considered trying to bring them close to flat again and edge join them using floating tenons and orienting the bowing in opposite directions but I figure the stress would just make the board really wonky. Is there anyway to reasonably make these boards useable at near their full length?
Bear in mind, this is more an exercise in me learning more about wood movement than an imperative to use this particular wood. I'm just curious.