Stone chip on bonnet rusting

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david1972

Well-known member
Joined
Jun 25, 2014
Messages
254
Location
County Durham
Noticed a big stone chip on the bonnet the other week and to my horror and surprise it seems to be rusting straight away. Anybody know if this will be covered by the warranty?

Thanks in advance
 
Why are you surprised? It's steel and will rust pretty quickly if the surface protection is broken.
 
My subaru is 10 years old, had plenty of stone chips on the front of the bonnet when i bought it but none had rusted. Just surprised it's gone right through the paint and primer I guess - must be thinner these days.

Any recommendations for repair specialists?
 
maby said:
Why are you surprised? It's steel and will rust pretty quickly if the surface protection is broken.
Not really. I used to drive Volvos quite a while back and it was remarkable how seldom rust spread from paintwork damage.
 
jaapv said:
maby said:
Why are you surprised? It's steel and will rust pretty quickly if the surface protection is broken.
Not really. I used to drive Volvos quite a while back and it was remarkable how seldom rust spread from paintwork damage.

And shouldn't with fully galvanised parts - which I thought all cars were today. But if the chip penetrates through to the steel that spot will rust but no further, as you need oxygen to produce rust and the zinc coating is supposed to seal the surface.
 
greendwarf said:
And shouldn't with fully galvanised parts - which I thought all cars were today. But if the chip penetrates through to the steel that spot will rust but no further, as you need oxygen to produce rust and the zinc coating is supposed to seal the surface.

The zinc is actually a sacrificial coating not a sealer. It protects the steel because it is #30 on the periodic table where as iron (Fe) is 28. This makes the zinc anodic to the steel and will be consumed first in the form of a white chalky powder.

Zinc is actually quite porous compared to other coatings.

Cheers

NAPpy
 
NAPpy said:
greendwarf said:
And shouldn't with fully galvanised parts - which I thought all cars were today. But if the chip penetrates through to the steel that spot will rust but no further, as you need oxygen to produce rust and the zinc coating is supposed to seal the surface.

The zinc is actually a sacrificial coating not a sealer. It protects the steel because it is #30 on the periodic table where as iron (Fe) is 28. This makes the zinc anodic to the steel and will be consumed first in the form of a white chalky powder.

Zinc is actually quite porous compared to other coatings.

Cheers

NAPpy

and, since the zinc is sacrificial and quite thin, it can make the damage look worse if it is not repaired quite quickly. If the paint is punctured in a small area and the zinc starts to erode, the metal directly under the paint damage will go quite quickly and the erosion can then extend out under the surrounding paint. Painted, galvanised steel is not maintenance free.
 
david1972 said:
My subaru is 10 years old, had plenty of stone chips on the front of the bonnet when i bought it but none had rusted. Just surprised it's gone right through the paint and primer I guess - must be thinner these days.

Any recommendations for repair specialists?

'Chips Away' comes to mind.

JimB
 
Yeah, thought of them.

Have to say I'm pretty peeved to have to be doing this on a modern day car. I thought we had progressed beyond this now
 
david1972 said:
Yeah, thought of them.

Have to say I'm pretty peeved to have to be doing this on a modern day car. I thought we had progressed beyond this now

I'm afraid that PHEV body work is very light weight in comparison with older "real" SUVs. Don't nudge a plastic rubbish bin as I did - that resulted in a complete new wing!
 
maby said:
david1972 said:
Yeah, thought of them.

Have to say I'm pretty peeved to have to be doing this on a modern day car. I thought we had progressed beyond this now

I'm afraid that PHEV body work is very light weight in comparison with older "real" SUVs. Don't nudge a plastic rubbish bin as I did - that resulted in a complete new wing!

:eek:
 
I have done 30,000 miles in mine and have many stone chips . Shame they use white primer on a black car . The Colour does not seem well adhered to the primer. Will get it painted at the end of lease
 
Ordered a kit from Chipex....remembered I'd used them before to deal with some chips on my wife's previous car and it had worked well. Will do some before and after photos when I do the repair
 
david1972 said:
Ordered a kit from Chipex....remembered I'd used them before to deal with some chips on my wife's previous car and it had worked well. Will do some before and after photos when I do the repair

Do you have any photo's?

MY ruby black MY16 has a few chips on the bonnet. Wanting to get these removed before any rusting happens!
 
piam said:
david1972 said:
Ordered a kit from Chipex....remembered I'd used them before to deal with some chips on my wife's previous car and it had worked well. Will do some before and after photos when I do the repair

Do you have any photo's?

MY ruby black MY16 has a few chips on the bonnet. Wanting to get these removed before any rusting happens!

Not done it yet as was too cold for paint to dry properly at weekend, plus had some damage caused to my scoob due to neighbours shed roof felt blowing off onto my car to repair as a priority
 
Ok.....stone chip repair round 1 - round 2 will follow later in the year in more ambient temperatures ;)

Before:



After:





Was never going to be a good as a factory finish, but happy that it's much improved already
 
That is looking pretty good already - better than the couple that I touched in with the official Mitsubishi paint pencil.
 
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