Have been working on extensive rust repair and mods on a 60 year old Fiat Abarth project. This is a rear engine car and has an area under the front where I cannot figure out how to get primer and paint in there. I made up a new battery box and it was originally welded in place. I could primer it (epoxy) before welding it in but wouldn't be able to get paint on some surfaces around it. There's also a couple of bumper brackets that are impossible to reach behind except may with a small brush.

Could this area be a suitable location for using POR-15 or similar product by brushing it on?If okay, can undercoating be applied over it? I media blasted the car last fall and it's pretty clean to bare metal in there except for behind the bumper brackets. I haven't used the Ospho I have on it yet. Could I use epoxy primer over the surfaces I can get to and use some POR-15 where I can't get to? What about seam sealer - can it be applied over POR-15? I'm pretty much a newbie at this stuff. I think many frown on using POR-15 anywhere tho?

Thanks!

What I've done is to use a 3M body Shultz gun with a rubber tube attached to the nozzle. I experimented with nozzles using a piece of copper tube and shaping the end, also used a nozzle from a garden sprayer, they all worked to varying degrees. either way you have to just shoot it up in the place and let the excess run out and clean it up with a rag. check around there are sprayers for this, Eastwood I believe has them. I would use the epoxy on everything and yes you can undercoat and seam seal over it no problem.
Jay D.

Yes, epoxy and no POR-15!
You can brush the epoxy on in those tight areas and then shoot your undercoating as described above.

Okay, so epoxy it is! I think brushing it on is a good idea as it will get undercoated and the primer doesn't need to look pretty. How can I get rid of the surface rust between the bumper bracket and sheet metal ahead of it? Not sure if you can see the brown area in the photo on the pass. side bracket. Some sandpaper and/or small wire brush followed by Ospho? I'm thinking of making the battery box removable which would help access a lot.

Just to double check, I'm wondering if I need to Ospho all the bare metal (and rinse off)? I assume so. I didn't treat it after removing all the paint last Sept. My garage has in-floor heating and the temp. all winter is about 70-72 degrees and the humidity is low at 20-21 RH%. I believe that doesn't mean there can't be flash rust tho?

While on the subject of POR-15, I have a few brackets and trailing arms under the car that need some kinda paint on them. The trailing arms in particular would need a lot of blasting work to get all of the rust off but same sort of thing, there's some spots where I can't get a nozzle or tool into to get at the rust. Would POR-15 be okay on these parts?

the rust areas your talking about, is it under the l shaped brackets on each side?
Jay D.

Here's a closer look at that rust area.

There'll of course also be some rust on the back side of these brackets that can't been seen. Doesn't feel like it's pitted or very rusty. Maybe just ignore it? Or some Ospho and perhaps followed with some POR-15?

I am not a fan of Por-15. It gets hard and does not expand with the metal has temps change eventually leading to cracks where moisture can get in.
********** epoxy stays flexible. If you leave a 1/4" layer to set up in a mixing cup, it comes out like dense rubber.

If you use Ospho, once the rust is treated you will need to reapply it and while still wet wash it off with soap and water to neutralize the acid. Only treat rust with it. If you apply to clean bare metal you will have serious adhesion issues.

Coat your suspension pieces in epoxy and then paint them if you choose.

'68 Coronet R/T wrote:I am not a fan of Por-15. It gets hard and does not expand with the metal has temps change eventually leading to cracks where moisture can get in.
********** epoxy stays flexible. If you leave a 1/4" layer to set up in a mixing cup, it comes out like dense rubber.

all paint does this, we call it a "puck" and yes all epoxy does it, all urethane, and if you left that 1/4 inch puck in the sun it would crack and crumble away.

PainterDave wrote: all paint does this, we call it a "puck" and yes all epoxy does it, all urethane, and if you left that 1/4 inch puck in the sun it would crack and crumble away.

Yes, the UV rays do a job on epoxy for sure. I primed this tractor cab that I built in 2012 fully expecting the owner to bring it back for me to paint. He never did. Here's what it looks like after almost 6 years of Flagstaff, Arizona weather.


Much better than I expected but you can see the primer deteriorating.

seriously I would just coat them with epoxy, 2 times how ever you do it then maybe give them a shot with the undercoat and you'll be good for a life time. Ospho is not a cure all if not used correctly and not the way they tell you to it can do more harm than good. they want you to put it on and let it form a crust then paint over it. this will do nothing but draw moisture and start the rust action again. you must remove the residue and clean it good. the only true way to fix the problem would be to drill the spot welds and remove them. then clean the areas and prime with epoxy. you will need to tape the areas that you will weld so that they have no paint, I use a weld through primer there. you'll still have a potential rust area at the welds, there you can thin some epoxy and try and force it in the weld area with a brush. it all depends on how you want to go at it.
Jay D.