andy everett wrote:
This Saturday I will rent a large sand blast set-up and blast 500 lb.
of steel ornamental fence and gate which will be set up outside. I
stopped by a NAPA auto store and bought "Rust Treatment, Destroys
Rust". The stuff is supposed to turn the surface metal black after
two coats. Should I use this stuff or should I just paint on a primer
after sand blasting, is this rust treatment step worth the effort?

It would probably be cheaper or the same money to take the stuff to a
sandblaster and have it blasted and immediately primed. If you do sandblast
it yourself I would suggest Black Beauty (coal slag) as opposed to sand.
Coal slag is low silica but has trace amounts of nasty stuff, so use very
good protection, like a powered HEPA filter.