So I have a small section (about 1.5 ft) of non-insulated ductwork with some rust right above my HVAC blower/furnace in the basement.
The rust seems to be caused by the water that sweats on that section when I'm running the AC.
I bought some hvac insulation that I could put over it, but I wanted to clean off the rust with a wire brush before I do so. My question is: do I also need to use some sort of rust stop or rust cleaner before I do so? And, if so, what kind of chemical/product would be safe for the ductwork? I don't want caustic or strong chemicals to make it into the ventilation system spreading fumes around the house or damaging equipment.
Do you think using loctite rust neutralizer would be safe?
https://dm.henkel-dam.com/is/content/henkel/TDS-1381192-US-Loctite-Extend-Rust-Neutralizer-Bottle-8-fl-oz-2018-04-11pdf
Additional Update: Henkel corporation returned my email and said:
We would not recommend that the Loctite rust neutralizer be used in an
enclosed system, such as, HVAC duct work.
Best Answer
Minimal solution is sand and prime.
Vinegar should not be used--for one thing it is so fluid that it will get into places where you cannot remove it and will cause corrosion. Naval jelly has phosphoric acid as the active ingredient and so it also should not get into places where it cannot be removed. But you could use naval jelly.
The safest removal would be simply hand or light power sanding and then priming. You probably would not need a top coat since the duct work is protected from the elements, but you could possibly get useful extra protection from a top coat.