I have been working on the undercarriage lately. I scrapped and cleaned one side and put Loctite rust converter on it, worked like a charm. Shiny, black frame now. Works a lot like the 3M Rust Avenger, much easier to get and less expensive.

I used a 2nd bottle on the other side, same process, but 24 hours later it is still milky white, looks like it is still wet. It has been a bit wet lately, but I have not driven it. I wonder if this batch or bottle is bad? The date bode looks like it should still be good. Plus, I bought it from a brand new Auto Zone, was probably not sitting around forever.

Do I just keep waiting, or will the humidity prevent it from curing?

Not much on the internet that was helpful. I emailed Loctite but not hopeful for a quick response.

 

I had never heard of this stuff before so I looked it up. It says that it's milky white but makes no mention of drying/curing to any other color, instead they say it acts like primer for further painting. Perhaps it's glossy or slightly reflective and what you are seeing on the first application is just thee result of reflecting black or perhaps the lack of light underneath that portion of the truck?

 

I use a different brand rust converter.. it's pink, converts to a milky white. Instructions say after it's done, rinse off with water. I use a garden sprayer, and then dry and hit with POR-15.

 

Rust converter just works on the surface. It's still rusting out under the coating.

I've seen frames look good, until you hit it with a hammer and it became a huge hole because the rust converter held its shape. The metal under the converter had rotted away.

If its surface rust, why not sand it and coat it properly? If its thicker type rust with depth it needs to be fixed with new metal.