Reagent or lab grade?

[Darryl Baird <dbaird@umflint.edu>]

I'm working on creating home-brew silver emulsions, using Reed & Jones'
SILVER GELATIN book. While looking for various chemical components, I
often find listings for reagent, technical, or pure grades of chemistry
available at varying levels of cost. I'm certain reagent (ACS?) grade is
the best, but do I need this level of quality for photo emulsions, or
would a technical or "pure" grade be ok?

thanks for any input
-- 
Darryl Baird