painting over "blued steel" - how to? surface prep?

[Sh3rpak!ng]

I got a bunch of steel from a sheet metal fab shop. All of it is this "blue color" that looks like some sort of surface treatment - I am not sure the technical term. Maybe it's called black oxide?

What is the surface prep needed before paint? Both with regards to rattle can paint, and also to automotive epoxy primer and body filler.

Here's a picture of said steel

[AndrewBird]

That is just scale that comes from forming it. A light sand is all you should need. You could remove it all with a wire wheel, but it isn't necessary.

[Sh3rpak!ng]

That is just scale that comes from forming it. A light sand is all you should need. You could remove it all with a wire wheel, but it isn't necessary.

great, that's what I was hoping to hear but wanted to be sure. Thank you