Question about rust...
 

[Closed] Question about rust on cars

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I nearly called the thread 'Question for Land Rover owners'..

Rather than try to fix the dodgy paintjob where I tried to fix the big stone chips on my bonnet, I bought a new bonnet for £50. This one though has some rust underneath. The actual rust is very light, but the paint has bubbled. So, given that it's not in a visible area:

1) Paint as usual with VW spray paint just not worrying about the finish. Is the clear coat necessary for protection or just cosmetic?

2) Buy cheaper Halfords grey spray and keep the more expensive but better matched VW colour (that I already have) for any visible parts.

3) Use Hammerite on the rust then a thin layer of grey on top? Does Hammerite actually prevent rust better than normal paint?

 
Posted : 16/08/2019 1:53 pm
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Matt black innit.

 
Posted : 16/08/2019 1:56 pm
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sand/grind back to good metal

Kurust if you really want.

Primer

Spray as per requirements.

it will rust again .

Given you cant see it - will it outlast the rest of the car - likely.

 
Posted : 16/08/2019 2:02 pm
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Por 15 works far better than kurust.

 
Posted : 16/08/2019 2:10 pm
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Spray as per requirements.

It's those rweuirements I was asking about. Is it better to use something like Hammerite or is there no difference between that and normal paint?

 
Posted : 16/08/2019 2:10 pm
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Hammerite is shit.
As above, POR15 is amazing. That or an Epoxy based primer.

 
Posted : 16/08/2019 2:22 pm
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Using POR15 is likely to cost a lot as it's expensive to start with and as it says on the label, once you part-used and closed a can you will never get it open again because the paint on the rim will set hard with atmospheric moisture and seal it for ever. I know this to be true.

 
Posted : 16/08/2019 2:31 pm
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Por15 or kurust.

It won't matter. It will still rust.

 
Posted : 16/08/2019 3:55 pm
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It won't rust again with POR15. Buy it from Frosts cars and you get lots of small cans so wastage is the min. You need to get the prep sprays as well. Look online for instructions as it is best applied in the dry .Brilliant stuff.

 
Posted : 16/08/2019 4:11 pm
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my land rover didnt get the memo re por15.

its still rusting.

 
Posted : 16/08/2019 4:13 pm
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it rusted with por15?

 
Posted : 16/08/2019 4:14 pm
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the chassis is yes .

ok its 33 years old but 2 years ago it was stripped to bare metal and sprayed with por15.

 
Posted : 16/08/2019 4:35 pm
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I fixed the stone chips on my original bonnet using normal paint and chip-ex. The finish is hilarious, hence the new bonnet, but they didn't re-rust.

 
Posted : 16/08/2019 4:41 pm
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I've had good results so far with ZG-90 spray

 
Posted : 16/08/2019 6:17 pm
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I did my fresh import RX7 underside over 10 years ago with POR15. No sign of rust on the bits I did.

You can get very small cans for a small cost. So much better than Hammerite. Only proviso is you have to paint over it.

 
Posted : 16/08/2019 6:21 pm
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It won’t rust again with POR15. Buy it from Frosts cars and you get lots of small cans so wastage is the min. You need to get the prep sprays as well. Look online for instructions as it is best applied in the dry .Brilliant stuff.

Exactly what I did on an ancient Mercedes - it worked a treat. Wear gloves!

 
Posted : 16/08/2019 6:23 pm
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To answer your clearcoat question: Yes. Maybe.

Most, not all, car paints these days are water based (leaving aside the aftermarket 2K etc). The clearcoat protects the water based paint, which is porous (on a micro level) and can allow the passage of moisture. It also isn't very hard, resistant to UV, heat, etc.

 
Posted : 16/08/2019 7:13 pm
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Good info thanks.

 
Posted : 16/08/2019 7:25 pm
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Leave it parked upside down so the oil leaks stop the bonnet rusting? Realistically if the rust isn't ground away it will come back, any treatment will just slow it down.

 
Posted : 16/08/2019 7:52 pm
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Couldn't afford to fix stone chips on the original bonnet but can afford to buy another bonnet and fix the rust and paint it? I'm out

 
Posted : 16/08/2019 8:13 pm
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What about a zinc based primer to stop the rust, then paint over that.

 
Posted : 16/08/2019 9:11 pm
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Couldn’t afford to fix stone chips on the original bonnet but can afford to buy another bonnet and fix the rust and paint it? I’m out

New bonnet was £50. How much is a respray?

 
Posted : 16/08/2019 9:25 pm
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por15 dries very hard and if used on something that flexes will crack.If you do want to reuse a tin put a double layer of cling film under the lid and it will come off easy next time. trail_rat as a landroverist of MANY years experience the chassis rot from the inside and so no external paint will stop them rotting. That's why galv is good because it coats the inside too.On one of my series vehicles fitted with galv chassis it is starting to disappear in places on the outside and will need rubbing down and painting but a look at the inside via a bore scope reveals it be in an as new (ish) condition.

 
Posted : 16/08/2019 9:29 pm
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I've not found anything (other than abrasive blasting) that reliably removes ALL rust. Anything else I've ever tried has always re-rusted far quicker than a proper job with a blaster.

In this instance, if you want to eke a bit more life out of a bonnet rather than a full-blown resto, I'd probably just leave it be. If the rust is inside the bonnet then it'll probably outlast the rest of the car, unless said car is something special/unusual you want to keep on the road indefinitely.

 
Posted : 17/08/2019 7:39 am