The painting that has several cuts in about 25% of the surface area? Don’t think that constitutes as a shapeless pile of dust.

So what % does?

Not a lawyer, but practically speaking copyright is lost when an item ceases to “exist” itself and can’t be restored. If you cut a painting in half - it’s absolutely still a copyrighted item. If you atomize it and don’t have technology to restore it, then copyright is meaningless. What item exactly is copyrighted?