Rust or some weird "converted" rust?

[stlcardinalsguy]

Noob question here, I'm stripping my truck cab that currently looks like this:

And getting to bare metal looks like this:

Is the black rust or has it had some sort of rust converter applied to it? I'm asking because while I would like to get to bare shiny metal, this is some really difficult stuff to get off. A wire wheel doesn't touch it, 80 grit Norton Gold on a DA doesn't faze it, those weird paint removal wheels won't touch it either. I took about 10 minutes sanding a 1 inch by 1 inch square by hand with the 80 grit and it came off but wrecked my paper....and took friggin 10 minutes.

Can I epoxy over this or do I need to completely get it all the way down?

 

[sprint_9]

This might be a good thread to read through. Short of media blasting, ospho can be a good alternative, how to use it and the results from it are highlighted.

Issue with milscale will spi epoxy stick?

So far everything was going perfect stripping paint down to metal. Today I was stripping my hood and realize it was a problem once I started sanding. The Hood was covered with all this crude that is the right side. So, I sanded one side so you could see a comparison. I went through about 12 80#...

www.spiuserforum.com

 

[stlcardinalsguy]

Great thread, sprint, thank you for pointing me in the right direction! Wasn't aware there was a such thing as black rust, looks like I get to become acquainted firsthand. I'll try the skyco ospho, looks like I'm in for a long haul unless I get a blaster which I'm scared to death of.