Prepping the Floor for Painting

I'm in the process of prepping the floor for priming and painting. This is a multi-step process that is critical to ensuring a rust-free bottom to the bus. Theoretically I'll never want to see the floor again as I'll cover it up with insulation, wooden frame, and then polyurethane covered wooden floor, so I need to ensure that it is flawless.

The first step is to remove any nails/screws that rise up from the surface. I accomplished this with an angle grinder and a rust removal wheel.

Next I swept the back which had a surprising amount of dust and tar/gunk buildup which I scraped off with a putty knife.

I made a solution of TSP (Tri-sodium phosphate) and set to work scrubbing the floor. More than anything, this is a degreasing agent to prepare for the Ospho which will eventually convert/prevent additional rust. Additionally, as the pH of Ospho is low (very acidic), it is an astounding etching agent for galvanized steel. This is where I ended today. Tomorrow I'm going to hose out the inside and drive out any remaining dirt so that the Ospho will have maximum effect.

So clean and so shiny!

Finally, I'll have to paint the metal with Rustoleum primer and then a Rustoleum Finish. Eventually I'll place down a wooden frame and insulation, but that won't happen until I get the steel walls riveted in.