Photo engraver of Magnesium sheets

["Koren Carpenter" <CarpentK@state.mi.us>]

I have a question from a customer on a shop that photo-engraves magnesium sheets.  They use nitric acid to dissove magnesium which produces Mg (NO3)2 in the solution.  They "develop" the exposed plates by washing them with trichloroethylene.  

The questions are: " What nitric acid decomposition products are likely to be vented?"    and  " Is there a better substitution or 'green' alternative to trichloroethylene?"

Any help on this would be appreciated.