Rust Spot Fix Question

[JFENG]

Once you mechanically remove as much rust as possible I recommend you use a chemical rust conversion treatment before any primer. There are very good treatmentssuch as PPG DX 520 (replaces by SC520) or POR -15 metal prep. These etch microscopic rust and leave a zinc-phosphate coating to prevent future rust formation. I’ll bet if you do this and do a good job top coating then your rust issues won’t come back.

If there is rust thru, it’s an entirely different matter and you should cut out and replace metal.

Good luck

 

[e9coupeMA]

Re the door.........I would say there is bondo in behind the paint and moisture has caused the paint to separate.

Hey Paul - the pics I posted are of the area underneath the window gasket and the larger pic is of the front qtr panel where I believe if there was/is bondo it would be obvious. Thanks for your comment though.

 

[paul]

Hey Paul - the pics I posted are of the area underneath the window gasket and the larger pic is of the front qtr panel where I believe if there was/is bondo it would be obvious. Thanks for your comment though.

Below are some pics of my car in the exact same area Pic 1 original car before sand blasting...Pic 2 after blasting...Pic 3 the remedy. I can see small pimples in your paintwork also........I hope was not like mine.

 

[e9coupeMA]

IMO, that is borderline surface rust. I think that no grinding or prep and adding por-15 would be sufficient. Not what I am doing with my car, but I wouldn’t cut a hole in that. My two cents...

IMO, that is borderline surface rust. I think that no grinding or prep and adding por-15 would be sufficient. Not what I am doing with my car, but I wouldn’t cut a hole in that. My two cents...

 

[e9coupeMA]

Markos - I have sanded the rusty area clean to the metal. What is por-15? What would you say are the steps I should take before painting.

Thanks!

 

[HB Chris]

Por-15 is a rust encapsulator and supposedly stops rust, it is used when it shouldn’t be I think.

 

[Markos]

Markos - I have sanded the rusty area clean to the metal. What is por-15? What would you say are the steps I should take before painting.

Thanks!

If you have removed all of the rust you don’t need POR-15. You are actually not supposed to remove the rust prior to using POR-15. This isn’t my area of expertise so I’ll defer to folks on this one. Glad you didn’t cut the area though!

 

[JFENG]

Just do the etch I recommended, which removes any microscopic pits of rust. You can use SEM rust mort as an etch by spplying it as directed and then sanding it off. If you do that twice it’ll be totally clean and ready for primer and/or filler.

 

[Drew20]

My own RoT is rust coming from underneath/ inside will always need to be cut out for a successful fix. This might be due to a moisture trap or inadequate protection on the inside surfaces of a previous repair. Rust which has come from the outside, ie a scratch or similar can usually be wire brushed, treated and painted if caught early. Maybe filler or thick zinc prime to cover over any pitting.
The bit by the windscreen looks to be surface rust only, so should fix up ok. Next question is paint... where to start the paint and where to stop, I would do the whole panel here as it has well defined edges, ie places to stop

 

[e9coupeMA]

Just do the etch I recommended, which removes any microscopic pits of rust. You can use SEM rust mort as an etch by spplying it as directed and then sanding it off. If you do that twice it’ll be totally clean and ready for primer and/or filler.

What type of primer would you recommend?

 

[JFENG]

I’d use an epoxy primer.