[HoosierDaddy]

Hi Sayed,
Is that the only bay area on your coach that is rusted that bad? If it is as bad as the pics indicate I would remove everything from the wall. Use a wire brush on an angle grinder to remove all rust AND paint. I would wipe it down several times with CLEAN cloth shop rags and lacquer thinner to remove any oil residue etc. I believe the por 15 metal prep would be a good idea in this application as well prior to applying the por 15 coating. Be sure your work area is well ventilated.

[newell_0]

Hi Sayed,
Is that the only bay area on your coach that is rusted that bad? If it is as bad as the pics indicate I would remove everything from the wall. Use a wire brush on an angle grinder to remove all rust AND paint. I would wipe it down several times with CLEAN cloth shop rags and lacquer thinner to remove any oil residue etc. I believe the por 15 metal prep would be a good idea in this application as well prior to applying the por 15 coating. Be sure your work area is well ventilated.

Fortunately, this is the only bay that is like that! As near as I can tell, the previous owner kept several containers of fluids including engine coolant that could have caused this. There is also a drainage hole on the floor of the bay about an inch or so in diameter that water could have splashed while traveling. Shouldn't there be a cover for it?

I will take all the "stuff" off the wall including the decals. Do as you suggested. I'm going to do it in two steps. First, do the floor, the back wall and wall towards the front of the coach. Then I'll tackle the wall where everything is mounted and lay them down on the floor of the bay. I'll try not to disconnect any of the power and air connections. From what I have read about POR 15, it is messy to work with. It will be a good learning experience, to say the least!

Thanks for chiming in!

Sayed

[Trainer]

Sayed,

Ospho, brand name for a dilute solution of phosphoric acid, is very easy to use to kill rust. Ospho reacts with ferius oxide turning it into ferius sulfate, an inert salt. Just smear it on to the rust. When dry, you are rust free and primed, ready for the protective coat of your choice.

Used for years with good results always.

[newell_0]

Sayed,

Ospho, brand name for a dilute solution of phosphoric acid, is very easy to use to kill rust.  Ospho reacts with ferius oxide turning it into ferius sulfate, an inert salt.   Just smear it on to the rust.  When dry, you are rust free and primed, ready for the protective coat of your choice.

Used for years with good results always.

Interesting! I hadn't heard of the Ospho brand of phosphoric acid. Thanks for the great info!

Sayed

[Trainer]

Oops, not being a chemist I erred on the salt that results from ferrous oxide and phosphoric acid. I believe it should be ferrous phosphate.

The bottom line is no rust anymore, no mess and no fuss.

[newell_0]

Oops, not being a chemist I erred on the salt that results from ferrous oxide and phosphoric acid.  I believe it should be ferrous phosphate.

The bottom line is no rust anymore, no mess and no fuss.

Thanks for the clarification, Rudy!

If there is paint in the area being treated, does it take the paint off too?

Regards,
Sayed

[Trainer]

I have not removed any nearby paint and I do not rinse. I just paint over the dried results.

[newell_0]

I have not removed any nearby paint and I do not rinse.  I just paint over the dried results.

How quickly does it dry at around 75 deg temp.? i suppose it depends on how deep the rust is and how much you put on.

Thanks

Sayed

[Richard]

Sayed,

Don't worry about it drying. Most of the prep solutions are phosphoric acid based including the one from POR15. They do recommend rinsing theirs. You can also use Naval Jelley. All of them work by eating away the surface layer of rust to get down to bare metal.

POR15 cures by way of moisture. It does not dry like we normally think of paint. So painting over a damp surface only makes it cure faster. The curing by moisture explains why an opened can doesn't last long in storage. Just the humidity in the air is enough to start the chemical reaction in the opened can.

[newell_0]

Thank you, Richard. The Naval Jelly may work out better for the wall.