Bad rusting stone chips please help

[Nigel Foster]

After being laid up with ill health and my 2015 Mazda left standing I've found it's got a number of "chips" on the roof.. actually caused by bird droppings.. some rusting already with disturbing cracks / legs working under the paintwork. It's all happened quickly like 3 weeks..

I'm reading through past posts but please can anybody advise how to deal with these whilst I can my health is not great

I feel like I might have to take the paint back considerably (to 5p /10p size for a couple) with.. fibre glass pencil (dremel?).. then use a rust inhibitor (degreaser? application of kurust?).. paint in with brush.. clear coat??.. lacquer?? wet sand ??

Any suggestions as to specific products and how far to cut into the paint greatly appreciated

I'm guessing a respray of the roof may be required long term, would anyone have an idea of cost?





Thanks for reading..

[soad]

Would a cover help for the time being?

[Jim the Sunderer]

I've used Kurust, the runny liquid kind not the thick stuff for park benches.

It's not broken through with rust in nearly a year.

I'd be tempted just to apply a bit as a stop gap.

[vikingaero]

Anything you do now will help the spread of rust/damage. For instance, if Mrs V. kerbs one of her alloys, the first thing I do is to cover the damage with Poundland nail polish until I have time to repair it properly.

It sounds like once you fix the damage, you need to protect the paint more with a sealant/wax.

[Belle427]

Scrape away any loose paint and rust and then try a converter product.
My experience of them isn’t great to be honest not sure what others think.
Can be tricky to get it perfect but anything is better than letting it get any worse.
I’d guess a roof re spray would be close to £300, depends how much time and patience you have really.

[Nigel Foster]

Appreciate the comments!

I put vaseline over the spots to prevent moisture ingress for now, but ofc that won't stop the existing rust from encroaching further.

vikingaero said:

Anything you do now will help the spread of rust/damage.

This is where I'm unsure what to do.

A detailer today recommended just picking out the visible rust, applying rust convertor.. then he would do the paint touch up and lacquer for me and polish out the 'legs' and the whole roof. He reckoned that would look fine and be good for 3-5 years?

My concern is.. where the 'legs' / crackling paint is, is that indicative of rust under the paint (..which would then return quickly bubble quickly and spread.. going against what detailer said)? Or is it stressed paint?

He reckoned if I tried to pick under those bits, I'd likely just cause more damage and make the problem bigger, perhaps lifting the paint further unknowingly, allowing more air to contact steel etc.

So looking at the pic here he's just suggesting working back the yellow area.

Is there a consensus for that approach?

I thought I might need to lift the paint marked in grey to get at all the rust, but I imagine with how these things go I'd end up working back to the red area.. which is about the size of a fingernail and when touched up would look ****.

Belle427 said:

I’d guess a roof re spray would be close to £300, depends how much time and patience you have really.

Only had one quote so far, £800 for respray would involve window out and stripping back headliner to remove sharkfin aerial.

There's no way would I attempt this myself.

Edited by Nigel Foster on Monday 13th June 20:06

[paintman]

You are correct that the spidery lines next to the rust spot are rust spreading underneath & lifting the paint.

If you de-rust the round visible bit but leave the spidery lines alone then thoroughly dry to remove any moisture & seal with paint then you MIGHT stop it spreading further.
The repair will be visible but it comes down to what you can live with.

The best solution is the roof respray option & to do it properly would be the screen & shark fin removal you've mentioned.

[Funky Squirrel]

vikingaero said:

Anything you do now will help the spread of rust/damage. For instance, if Mrs V. kerbs one of her alloys, the first thing I do is to cover the damage with Poundland nail polish until I have time to repair it properly.

It sounds like once you fix the damage, you need to protect the paint more with a sealant/wax.

Works for any paint or lacquer damage too!

[Nigel Foster]

Thanks @paintman

I wish I could make a decision.. there's no easy option here is there. 🙄

Feel this is going to be an expensive lesson : if you're going to be ill make sure you get someone to wash your car.

[Belle427]

My experience is that if you don’t take it all right back it will gradually get worse.

[CarCrazyDad]

Doesn't really look like original paint on the roof either to be honest - it's probably been painted before hence why bird crap has marked it, you'll get some crazing from bird dirt but it won't cause rust on a factory panel unless left for many many months in arid conditions (the paint heating up and contracting in the sun around the bird dirt is what does most of the damage)

You can stop it rusting at home - but it will look crap

Or you can leave it, and it will get slightly worse over time (many many months)

Or you can pay for professional to deal with it

Since the rust is underneath the paint (in the substrate) it will need the area stripping to bare metal to repair "properly"

[Nigel Foster]

I wish I could "like" posts as all contributions are appreciated!

I've spoken to 3 bodyshop guys and 2 detailers (all of whom recommended by trusted 3rd parties) and received mixed advice.

All good guys, none hustling for business..

• 1x detailer recommended working back all the rust, priming then wrap the roof.
• 2x bodyshop guys said window out for a respray maybe £1k+.
• 3rd bodyshop guy said he could do a respray for £400.

He and 2 others recommended as per @paintman :

Take the visible rust back (so approx to the yellow area) .. apply kurust etc.. paint.. lacquer and buff out the 'legs'. Then monitor.

All reckoned it would hopefully be years before issue as it's sealed from the air, and if bubbling does appear, nothing lost.. go to plan B and respray. So I'm going to do this but..

A respray for £400 to 'eradicate' the problem sounds decent.

Is it a case of ' you get what you pay for '?

He comes recommended to me by three trusted people, and unlike the other two was willing to do it without removing the screen. I'm not sure why the screen must be removed.. seems to introduce more risk, and pulling the window seal forward seemed to allow access to the roof panel to spray.

Any thoughts?

[paintman]

If you 'buff out the legs' then you will find you've taken the lifted paint off the legs & exposed the rusty tracks on the roof. Which is why I said to leave them alone in my earlier post.

Clean the rust spot, leave the legs alone & use a touch-up kit with a toothpick or straightened out paper clip to apply the colour coat & the clear to the spot.
Won't be perfect & being a flat horizontal panel it will be noticeable. Esp as it's at/near eye level, plus you know it's there so you will look for it every time you go to the car.

For anything else then have the roof resprayed.
One of the reasons for removing the screen is to be able to do the whole of the roof & if there is any rusting at the seal to roof joint then it's the only way to stop it as any rust left under the seal will simply spread again & spoil the job. Won't take very long to happen either.

[Nigel Foster]

Thanks again, paintman

One of the bodyshop guys was showing me what he would if it was his car, he buffed the legs off of one of the marks till they weren't visible, it didn't expose any rust tracks or primer it looked normal again. I think it might look worse in the pic than IRL? He thought I was being a bit OCD about the whole thing.

I'm actually wondering if there is rust under them legs.. because I couldn't find any pics of similar looking chip marks online. I've seen similar marks from where bird muck lime has crazed the paint on the surface, and the mark in the pic was under bird poop. Maybe lime + proximity to a stone chip produced crazing on the surface.. I'll defer to your judgement, but will find out soon enough...

None of the chips are close enough to the window to have rust from them reach the edge / seal, and I don't see any bubbling there.. which I why I wondered why it's necessary for the screen to come out... (if it can be painted right to the edge, which in my layman opinion i would think so, as there's enough of a lip to pull the seal forward and work around it slightly).

[Nigel Foster]

CarCrazyDad said:

Doesn't really look like original paint on the roof either to be honest ..

I've wondered this..

One other panel looks flat to me like it's been resprayed, no 'orange peel' effect, but I don't know really.

[Belle427]

I don’t know many body shops that would remove the screen if the seal can be pulled back, I’m sure there are some but not in my experience.
The aerial is another matter, I would remove this without question unless again it has a seal that can be pulled back.

[Nigel Foster]

That's good to know Belle..

The bodyshops I spoke to that insisted on it, it seemed to relate to warranty 'protocols'.. ie it must be done screen out for them to issue their warranty - company policy.

But the warranties didn't cover rust anyway...

[paintman]

Nigel Foster said:

Thanks again, paintman

One of the bodyshop guys was showing me what he would if it was his car, he buffed the legs off of one of the marks till they weren't visible, it didn't expose any rust tracks or primer it looked normal again. I think it might look worse in the pic than IRL? He thought I was being a bit OCD about the whole thing.

I'm actually wondering if there is rust under them legs.. because I couldn't find any pics of similar looking chip marks online. I've seen similar marks from where bird muck lime has crazed the paint on the surface, and the mark in the pic was under bird poop. Maybe lime + proximity to a stone chip produced crazing on the surface.. I'll defer to your judgement, but will find out soon enough...

None of the chips are close enough to the window to have rust from them reach the edge / seal, and I don't see any bubbling there.. which I why I wondered why it's necessary for the screen to come out... (if it can be painted right to the edge, which in my layman opinion i would think so, as there's enough of a lip to pull the seal forward and work around it slightly).

Lift the edge of the seal where it sits on the paint with a plastic filler spreader & push a length of single plastic covered wire under the seal.
This will keep the seal edge up while the panel is being painted. The paint will go under the seal.
Once painted & cured remove the wire & the seal will sit on top of the new paint rather than there being a visible edge where the seal is.

[V8covin]

The spider legs ARE rust,they just haven't broke through the paintwork yet.
In time, moisture will get under the paint and it will start to bubble.
Left long enough that rust spot will become a hole as the rust eats it's way through the metal.How long ? well put it this way rust doesn't stop of it's own accord.
If I were doing it I'd spot sand blast the rusty areas to be sure it's all gone,if it's pitted you won't get it all with a grinder.

The reason they suggest taking the screens out is if they're bonded,otherwise you get a build up of paint on the trims,with ordinary rubber seals they can be lifted away either with tape or a length of string.
If you intend to keep the car I'd get it resprayed before it gets much worse but there's no point them just sanding it off and repainting it without removing every last speck because it will return

[Belle427]

Just out of interest how would a pro deal with rust like this?
Use an acidic removal product or just go back to clean metal?