How good does ospho work to neutrilize rust and etch metal and how is the best way to use it? Thanks!!

Ospho has phousphuric acid in it which neutralizes the rust, if your doing exterior surface with it I would spray it on then scrub with a scotch brite pad then rinse it off with water then dry it and prime as soon as possible. If its a hidden surface you can spray it on and leave it because it has some type of sealer in it, well thats what the bottle says. Good luck.

My understanding is that Ospho leaves a Phosphoric acid film to protect the metal. If this is the case you would NOT want to apply an etch primer over it. The ecth contains acid it's self and the acids will attact each other, loosing adhesion from the metal!

To follow up with an epoxy primer would be fine. BUT I would only do this if the epoxy primer tech sheet said it was ok.

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