epoxy primer question re-run

i read 4-5 threads about having rust develop under primer cause it wasnt painted over soon enough. i had this happen with 2k primer and now know why. what im wondering is epoxy dtm any different? looking to clean up the window frames and prime before i install glass but it will be garage kept/ drove for a year or so unpainted. am i waisting time and paint doing the rest of the roof?

 

cured epoxy primer will protect the metal. i am not sure that answers the question?

 

maybe not? just saw people saying it can get moisture under it if its not top coated. i want to know if epoxy will do it oj just 2k

 

I believe it has to do with the polyester primers absorbing moisture over time if they aren't top coated or 'sealed'. Good Epoxy primers are water proof and seal the metal. I have a photo of a repair from over twenty years ago that developed rust between the filler and the metal that I only found by stripping it down.

 

2K primers will absorb moisture if not top coated

 

My Falcon had an Epoxy primer on it for 8 years it sat out all year rain, snow, etc.I can't speak for anyone else, but I had no problem.

 

my rule of thumb,,,,if you have bare metal, the best thing to do is epoxy prime it that day,,if it sits in bare metal for more than a day, metal prep it with dx579 first, then epoxy it.....l

 

Epoxy primer is NOT a topcoat, and WILL eventually degrade. Rust will form underneath. You might not see it, but it will be there. When that will happen is anyone's guess. What brand, how many coats, severity of the weather it sees, humidity, etc. all play a part in how quickly it degrades. 5 coats of good stuff in SoCal might last years, but outdoors in the NorthEast, might only be a year or less.
You'd be surprised at what you will find UNDER paint or primer that, on the outside, looks OK.

 

thanks i think im gonna do the whole roof since there is already rust where the old paint delaminated. ill just go back to bare metal when im ready to topcoat.