Fuming doesn't seem to have clear negative effects on wood properties (strength etc). Fuming allows you to bend wood without heat (dry or wet).
At the molecular level, ammonia dissociates hydrogen bonds between molecules, making the wood matrix essentially loose, and allowing wood strands (cellulose chains and lignin) to move more freely, slipping by each other instead of exerting tension and compression forces on each other when bent. Once the ammonia has evaporated, hydrogen bonds are restored (new ones). This allows you to make more extreme bends than with heat.
I don't see any reason to use this on green wood. Just be patient and dry your wood the normal way.
