Wondering what the consensus is on using zinc to spray on rust after the base metal has been blasted?

Has it been used long enough to see if it has any negative effects?

.. or rust converter for lightly pitted areas not sandblasted...snake oil?

Using zinc on steel has been done for at least 70 years, it's called galvanizing. The zinc corrodes instead of the steel.

Flame spraying of zinc, aluminum, or a zinc/aluminum mixture is very successful in preventing corrosion to steel.

I have a friend who at one time had a '50 Merc that was reported too have been built with a galvanized steel body as an experiment by FoMoCo.

The problem with galvanizing is getting paint to stick to it. The zinc forms a very thin layer of zinc oxide which must be removed or the paint will slide off in sheets at some point.

A good film of paint is supposed to prevent corrosion. If you get all the rust off underneath it and put it on properly, it'll last a long time.

Rust has at least two forms, the oxidation progresses with time. Rust converter pushes the oxidation process to its final stable form, then puts a layer of paint over it.

R.