need some guidance.

I have a 98 ex that a family member owns and I work on. Ok, so the car is spotless except the spot that is at the bottom front of the rear quarter panel. It'd be on the spot at the exact edge of the bottom of the rear door, but on the car, not the door. (Its a sedan) Does that make sense? Open rear doors of the 4 door, and look down into the corner...there. lol

It continues to bubble with rust. So here's what I have done. I took a sanding wheel and grinded it down to bare metal, applyed a rust converter then painted with a rustoleum that matched the cars paint. (Did 3 light coats, 0 clear) I did it in the middle of the summer, and had to redo it around Aug 15. Yesterday I saw the car and noticed its yellowing just ever so slightly, but looks like its coming back.

What's causing it to continue to keep coming back?

Did I miss some when I went to bare metal?
Do I need a better rust converter/inhibitor?
More paint?
Better Paint?
More coats?
Clear Coats?
is por15 the only option?

Please guide me---
I dont want it to get any worse, and I dont want to repeat this every 2 months. Im about at witts end and about 15 mins from dropping it off at a body shop, lol.

 

Rust happen because of the oxidation. And oxygen is in the air. In other word, the surface underneath the paint is somehow in contact with the air somehow. That is why it's rusting. Maybe your problem is from the inside and not the outside. So the rust is coming from the inside to outside and causing the outside paint to chip.

 

I'm sorry but Rustoleum paint does not work. Or in all applications I've seen anyway.

Your process should have been the following

-When painting you only need to sand down to primer, however when repair rust you must grind till no rust or black metal.
-When your using POR-15 you need to use its step 1 and 2; 1)Marine Clean Degreaser & 2) Prep & Ready, recommended products.
-Apply POR-15
-Sand with 360
-Apply second coat of POR-15 after you've used its step 1 & 2 process once more.
-Sand with 360
-Apply Primer
-Paint

IF your uncertain or want to verfiy how to properly use POR-15 call the 1 800 number. I got a hold of someone helpful within 3 rings.

Whats causing it to come back I'd bet on the rustoleum.

 

^ yea....I have the same feeling with rustoleum...its junk.
Ill redo it tomorrow (however doubt Ill be getting por-15 in a day)
Ill get better paint though from a auto supply shop.

 

If you want to come to Toronto for the weekend I can give you enough por for the job

 

why not grind to bare metal and prime

 

id be all over this (if it wasnt like a 18 hour car ride) + whatever boarder fiasco Id have to endure.

 

all i can say is be proactive not reactive or the rust will get out of hand