I've got a gallon of Picklex sitting on the shelf, but I haven't used any of it yet. I did a test spot, and it turned the rust black, but I'm not sure how to use it. Do you spray it, wipe it, brush it? When you are ready to prime, does it need to be sanded, removed, or just sprayed over?

What type of chemicals do you use and what is your process?

For the interior, I was thinking about just using Zero-rust. For the exterior, I'm going with an expoxy primer. I have been debating for some time now on what rust removal route to take.
Sanding disks and/or Scotchbrite discs, sandblasting, chemicals, etc.