Rust converter only gets the surface of the rust. It doesn't form some kind of magic seal like they'd have you believe. It must be removed first and then rust converter used to get rid of any small bits that you can't see with your eye and only then painted. It'll come back otherwise.Rust converter then touch-up paint.
You're quite correct on the point of seal it up so no air or moisture gets in and there will be no rust. Good call with the vasoline, it will help. I did something similar with my old car. I wanted one more year out of it and the brake lines and oil pan were all rotting out. Coated them in multipurpose grease, worked great.Sorry for my absence and thank you for the helpful replies!
I sealed the air out using vaseline whilst mulling over what to do.. and my plan is to A) touch up the spots temporarily.. but as I like the car I'm considering B) getting the roof resprayed.
I have spoken to a few a detailers and bodyshops and been advised that if the spots aren't exposed to air, the rust shouldn't progress, at least it will inhibit progress for a long time ie months maybe years, and can be monitored for any bubbling under the paint. It does seem to look worse in the pics than IRL btw.
A) For the touch up I have picked up..
Fibreglass pencil.. to pick back any loose paint
Isopropyl alcohol to degrease
A little polish
Rust convertor.. I see some debate going on here! This is what I've got : Kurust
Professionally mixed paint to match the car colour code (I also have a Mazda touch up stick - but this should be better)
Some cocktail sticks
So plan is scratch out the visible rust with the pencil (yellow area of the spot below), degrease, apply some rust convertor, paint, polish the spiders legs/tracks slightly so they aren't prominent (up to red circle), then liberally apply lacquer to cover in excess of the area of concern.. buff it all up, and shouldn't look too bad. As air cannot reach the rust, I'm told this should hold up for a decent while, according to bodyshops I've spoken to "as long as I keep the car". 🤷♂️
Any good? I could of course sand back to the red line..
That said.. I'm likely to go for
B) Roof respray. I've had quotes of £300, £400, £1000+, and £1400 GBP.
The higher quotes were from places that deal with insurers who made a bit of a fuss about removing the sharkfin (seems like you just remove some trim and carefully reach into the headline?), and they also wanted to remove and replace the screen and more. As the screen is not bonded to the roof (correct me if I'm wrong!) and no rust seems to be that near the screen, I don't see that being necessary?
The chap who quote me £400 came recommended by three trusted friends, reckons the window seal can be pulled forward (will that damage it?) and the respray look good as new. I'm inclined to go with him. He actually encouraged me to just touch up as described and monitor so wasn't hustling for work.. but I'm OCD so would like to have confidence the problem is gone for say ..4..5 years. I've been advised by a paint sprayer that it may needs spot sand-blasting to ensure that? Sounds a bit OTT to me..
Anyway.. any thoughts.. ? This will be my first respray if I go that route..
BTW I believe @arathol is correct and it's stone chip X bird poop lime. Personally until the paint is lifted I'm not convinced those 'tracks' are rust underneath.. everybody says it is.. sure.. but can you find a picture of a similarly rusted stone chips? I reckon it's paint stress caused by the lime, that has crackled from the point where the stone chip delaminated it. If you look at paint damage from bird poop it can stress paint without causing rust. I'm probably wrong, but that's my theory atm. Definitely the legs/tracks appeared within 2-3 weeks, and were all under bird muck. Seems like rust would take longer to do that..
Well having had similar stone chips go to rust on my car, I stripped the rust, treated the metal, painted with touch up since that's all I had, and then buffed it to feather it in. So sort of yesThank you.. from the 'bottom line' here.. I'm guessing if it were your car you would be sanding back to that red circle at least
Another suggestion I've had is to do just that, prime it, sand it, then just wrap the roof. If the car was white I might be keen on that!
I think that would make the car very hard to sell if the need arose...