Floor Pans- Rust prevention and Tunnel treatement, advice needed Options

[highways]

Hi all,

I'm working on my floor pans... I have them wire brushed down to bare metal. They are in overall decent shape though there is some rust around the perimeter where they meet the longitudinals. These corners seem innaccesable to all but a small wire brush (toothbrush size). Question is:

1. Should I apply POR 15 Surface Prep, then POR 15 to get in cracks, then Seam Sealer, then maybe another coat of POR 15 over Seam Sealer?

2. Or, should i just do Seam Sealer first over bare metal, partial rust areas around the perimeter? Then follow with POR 15?

Second question... the smaller 'cross tunnel'.. the one where the front seat adjustment bracket mounts, is in poor shape. Rust inside it looks bad... some of the lower edges are gone but it's still largely inaccesable to any tools or painting. I think my options are:

A. Drill some holes in top, blow it out, and spray as much paint in there as I can and call it a day.

B. Cut it out and weld in replacement. But is this part even available? And still how do you paint the bare metal inside after you've welded a new piece in?

Any advice would be appreciated.

[sean_v8_914]

Perry, you saved me alot of typing. Your proceedure is similar to what I like to do. no single-step process is going to get it done right. one proceedure or product will not cover all conditions or locations.
POR 15 is no good on cleaned metal, it WILL peel. wire wheeled and cleaned metal MUST be etched.
home depot, lowes, Maynards have TSP and Ospho or jasco
sherwin williams, Frazee house paint stores have Ospho, jasco, metal prep (phosphoric acid based)
body shop store, TCP global.com, tri city paint has POR 15 brand metal ready, SEM rust mort, PPG dx 530. I like SEM Rust Mort and Metal Redy because they have a zinc component. SEM is agressive stuff.
ready the instructions carefuly. SEM Rust mort is awesome and powerfull but if layed on thick and left to dry it will be gummy mess.

my advice to anyone trying these proceedures recommended by the pros is try the chemicals on test pieces of metal. there are alot of subtlties in teh timing and technique that we forget to mention or just take for granted because we do it often.

the key is allowing the chemical reaction to happen. the deeper teh rust, the longer you want it to stay wet with the acid. go slow. the little splashes will not feel good on exposed skin of finished surfaces