It never stops being poisonous, so far as I know. There's also the whole problem of the fact that the warriors first came out of the ground with colors, and they faded within eight hours of being excavated, so if they dig up Qin himself, they really want to have the technology to preserve what they find.

Yeah! I had no idea they had weapons, either! And bronze ones with the hardness of tempered steel... which were then plated in chrome of all things.

It just fascinates me.