Ospho on Aluminum Floor Pan

[jessicake1137]

I'm converting a short bus with an aluminum floor plan, and am in the rust removal/prep phase. We just started wire brushing to get any rust and oxidization off.

Is a rust converter like ospho okay to use on aluminum during this step? Forgive me if this has been answered, I couldn't find anything and Google is conflicting! Seems most floors are steel.

We'll then have to patch the ~100 bolt holes from the dreaded seat rails- we're thinking sikaflex and aluminum foil tape- after we use the rustoleum rusty metal primer. Open to suggestions though, I'm interested in the penny method as well!

TLDR is a rust converter like ospho recommended for aluminum floor pans?

 

[DeMac]

Rust and/or Aluminum

Hello. Welcome to the skoolie.net

After your fifth post, you can post photos.

I'll ask a few questions,
If you answer them in four separate posts, then the site software will allow you to post photos of your bus & the floor.
We Love Bus Photos!


1. Most importantly, what are you going to do with that bus?
(business, camper, toy hauler, tiny home....)

2. What kind of bus do you have?

3. Where did the bus spend its service life?

4a. Is it possible that the Aluminum has glue or grime and not really rusty Aluminum?
OR
4b. Is it possible that the rusty floor is actually steel?


(Ospho IS perfect for rusty Steel,
while Aluminum ought not rust)



(Edit: You filled out your profile after I wrote this.Awesome)

 

[jessicake1137]

Hi DeMac, thanks for responding! I haven't had a chance to post a full reply till now, apologies, I'll try multiple posts so I can add pics.

1) Mostly a camper, my husband and I plan on using it for traveling around the country for a few months at a time.

 

[jessicake1137]

2) Bus info is updated! Chevy duramax diesel 6.6 L chassis, bluebird bus. It was a spare handicup shortie for a school district, so low miles (~100k). Runs amazing.

 

[jessicake1137]

3) Service life was in the Tennessee mountains. Rust is minimal, there is some on the frame underneath and on the steel wheel wells but not much.

 

[jessicake1137]

4) Rust on the actual aluminum is VERY minimal and it's mostly just white oxidization with a tiny bit of pitting where the oxidization occurred. So, we've been thinking we may not even have to keep wire brushing on the actual aluminum. The rust is really just on the wheel well panels and the walls.

 

[jessicake1137]

Floor Pics

Pics attached! One wheel well we've already wire brushed, and one not. Some of the floor has already been wire brushed. Now we're even questioning if we need to use rustoleum or not since it is aluminum (I feel like yes to be safe). Still learning! Thanks!

 

[DeMac]

Almost There, Looks Great

Pics attached! One wheel well we've already wire brushed, and one not. Some of the floor has already been wire brushed. Now we're even questioning if we need to use rustoleum or not since it is aluminum (I feel like yes to be safe). Still learning! Thanks!

----------

Most of the factory floor looks ready for a coat of bare metal primer. Especially the steel patches. However, I would first treat the patches over the wheel humps and the bottom edge of the walls with Ospho. The lowest portion of the wall looks the worst. May be galvanic reaction to the Aluminum flooring?

Whether using foamboard, lumber, plywood, carpet, vinyl... most adheasives will adhear to the primer, better than aluminum or galvanization (zinc)...

 

[Jolly Roger bus 223]

take a magnet or a level with a magnet and see if it sticks to your floor.
magnets dont stick to aluminum true stainless steel or copper.

 

[jessicake1137]

Okay thank you so much for the tips! Wasn't thinking of adhesion. Yes, the corners between the floor and walls are pretty bad so we'll wire brush and ospho those. Would you recommend pennies & sikaflex for covering all the bolt holes, or sikaflex & foil tape? We're also deciding what to use to cover the wheel wells since there's gaps and it sits lower than the aluminum...do you have any suggestions?

 

[desrtdog]

For holes in the floor, I used plastic hole plugs from WidgetCo.com...used a paintable sealant to secure them in place; primed and painted the floor; then put Kilmat-type material over the entire floor (actually used Noico 80-mil butyl sound deadening material...available on Amazon). Sub-floor (3/4" foam board and 1/2" ply) went on top of that, and I primed/painted that as well for a bit more protection while building out the interior.

I've seen where people use pennies, but I had about 600 holes to fill - my seats were bolted to L-track that was riveted to the floor every 2" (thanks, Bluebird). Note when painting aluminum or galvanized metal, you need a primer that is meant for those - I don't think the standard Rustoleum is advised in that application.

Post #19 of my build thread here details the floor work.

 

[TaliaDPerkins]

Galvanic corrosion?

If aluminum and steel touch, the aluminum should corrode.

 

[TaliaDPerkins]

Some idiot...

Left me a very rude private message about this post, "If aluminum and steel touch, the aluminum should corrode."

Lol. Why do you write this things before you Google. Just as easy to look smart as to look..... Well

https://www.shapesbyhydro.com/en/material-science/avoiding-galvanic-corrosion/

That said, galvanic corrosion of aluminium occurs:

• Where there is contact with a more noble metal, such as copper and carbon steel. After magnesium and zinc, aluminium is normally the least noble metal, in combinations with other metals.

Some people might recall that magnesium anodes are attached to steel boats so the anode corrodes before the steel does, protecting the hull. Aluminum is actually the next best sacrificial metal, next best to magnesium, that is in common use.

 

[TaliaDPerkins]

A wrinkle I was not aware of.

https://boatzincs.com/categories/zinc-anodes/hull-anodes/bolt-on.html


Magnesium is only good for freshwater. I did not know that. I wonder why?


In any case, should apart of the floor be aluminum plate, it seems to be electrically isolated from everything else. Leave it alone, it should be ok. What you think may be aluminum might be especially thickly coated hot dipped zinc coated steel -- a magnet would still be attracted, if it were that.




The heavy gauge channel rusted at the bottom of the wall probably is not rusted enough to compromise it much, but I can't think of a way to thoroughly scrub and brighten the whole surface for painting. Taking up the whole floor?


I think cleaning it properly on all sides is the hard problem.