'72 Dodge Challenger Saga

[rhamson]

I have a dilemma with some pitting I discovered on the roof. I started stripping it and sanded to metal and found that filler had infiltrated the pits to where I can't get it out without fear of sanding the metal too thin. The car from the fender tag had a white vinyl roof on it and I guess it percolated some rust under there. Is there a chemical to remove the rust other than a POR 15 remedy? Any thoughts? I am worried if by leaving it may come back to bite me as bubbling later. The clowns that prepped and painted this car before I got it left a lot of rust around the windows that were already bubbling. There is no telltale signs of it on the roof and that has had finish paint on it for at least four years.

[rhamson]

Another Pic.

[FY1Cuda]

Wire wheel to get the pits as clean as possible. Then use Evaporust by saturating old towels with it and laying them on  the roof overnight.  Cover the towels with plastic to limit the evaporation.

[ec_co]

portable soda blaster to get the rest of the filler out?

[rhamson]

Wire wheel to get the pits as clean as possible. Then use Evaporust by saturating old towels with it and laying them on  the roof overnight.  Cover the towels with plastic to limit the evaporation.

Once I treat the surface with Evaporust and clean it with what?, is it ready to accept a epoxy primer?

[rhamson]

portable soda blaster to get the rest of the filler out?

Great idea but I don't have a soda blaster and it is not a big enough job to get one or rent somebody to do it. Thanks though!

[Chlngrcrzy]

Is it just pitted in places, or do you have rust around the edges of your roof panel?

[FY1Cuda]

Rinse it off and dry the roof real well before priming.  I would probably wire brush after the evaporust and before the epoxy.  BTW, Evaporust is available at Harbor Freight.

http://www.evapo-rust.com/product-info/

[Edison1970]

I cleaned my fender with muratic acid.  It cleaned all of the pitting in the metal completely.  You really have to rinse it well afterwards to remove all of the acid residue.  There was an article in Mopar Muscle a few months back that covered this process pretty good.  Make sure you don't have any stainless steel in close proximity.  It will oxidize it very quickly.

[rhamson]

Is it just pitted in places, or do you have rust around the edges of your roof panel?

The edges are good. I have sand blasted the window and door channels and there was some deep pitting but I treated that and now I am striping and sanding the roof and body panels to keep from warping anything. It is in the middle of the roof panel and I have ordered a few products that work well with primer and putty/filler.

[rhamson]

Rinse it off and dry the roof real well before priming.  I would probably wire brush after the evaporust and before the epoxy.  BTW, Evaporust is available at Harbor Freight.

http://www.evapo-rust.com/product-info/

I ordered some. Thanks.

[rhamson]

I cleaned my fender with muratic acid.  It cleaned all of the pitting in the metal completely.  You really have to rinse it well afterwards to remove all of the acid residue.  There was an article in Mopar Muscle a few months back that covered this process pretty good.  Make sure you don't have any stainless steel in close proximity.  It will oxidize it very quickly.

Thanks for the advise.

[Topcat]

The Evaporust works really well but you're not done after that.

You need to blacken the rust using a phosphate metal conditioner.
I bought mine at ACE hardware. It was called Crud Cutter. Ospho works well too. As long as it contains phosphate, they'll all do well. 

What you do is dilute it per instructions, and apply it with a paint brush cut short so the bristles are stiff. Work it vigorously into the pitted areas. Let it dry for 20-30 minutes. Then use a spray bottle and soak well with water. Wipe that off and let it dry.

Repeat the process!

A white film may show after drying. Use a 3M scotchbrite pad and scuff off this residue.
Now you're ready to Epoxy prime. Try to do that within 24 hours after prepping the metal.