Great video, the bluing really makes the pattern jump out! Do you have any health concerns with the bluing salts? Once the water/solution is boiling I would think the steam would be hard on the lungs.I may have to give that a try someday, if I can get a handle on making Damascus.
No, there are no really toxic vapors or anything of any consequence in volume.
Some decent ventilation is all that is required.
However - the liquid, hot salts are like Alien blood! Molten. Dangerous. Caustic as heck.