Floor pan sealing from underneath

[kjandb]

Complete noob here, so go easy on me. I've been learning a lot from this site about replacing floor pans and got this far. I plan on sealing the top with POR15 and then seam sealer (is that the right order?). But I realized I have no clue what to do on the bottoms side - right now it's just raw metal. I'm thinking I should have used something on the bottom BEFORE welding it in place but I'm past that point. And I don't think using POR is an option any more. In additional to sealing the seams on the bottom side what should I use on the bare metal (or at least the part I can see from underneath)?

[Atlasts]

Jeep Floor.jpg

On the top side, I used etching primer and color matching paint. Underneath, I used etching primer, top code and 3M profession undercoating since my Jeep J10 was under coated when new.

BTW - I forgot seam sealer over the seams of the new patches.

[SJTD]

I'd use some of the wax stuff inside the channel. Some sort of etching primer, seam sealer and paint on the outside then maybe some kind of undercoating.

[Phils67]

A weldable primer before installing is what I've used on the lower ends where it meets the hat channels and such. Raw metal flash rusts overnight and just all downhill afterwards. I can't recall the company or product name but if you Google I'm sure you can find it, it's a metal sealer/coating that can be fogged into frames, hat channels, etc, basically any hard to get to spots and is applied after the welding is done (obviously when cooled). I believe maybe lizard liner but don't hold me to that. Finish with 3m professional undercoating. That's the ONLY undercoating I've ever used that doesnt turn into a sticky glue-like mess and actually holds up over time. If used anywhere you POR15, spray while the POR15 is still in the tacky stage or it'll just peel off later. Has to adhere to it.

[akguy09]

When I replaced mine, I welded in the bare floor pans. seam sealed and painted the inside. Then underneath I seam sealed primed and painted.
I figure it took 40+ years to get this bad, so I'll never need to replace it again....i'd be almost 90