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Stop Rust coming back????


roboboyo

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Hi Guys

 

Ive sanded the rust out, primed the area, painted it, but the rust comes back through :nutter: :nutter: :nutter:

 

as the symbol states, its like banging my head against a brick wall!!!!!

 

 

Anyone got some advice on a teqnique, or rust prevention product, i want to put this to bed!!!!!!

 

 

cheers guys

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You probably should get acid etch primer. It basically eats into the metal like acid but protects it from rusting on top or that you should put some decent high build primer to block sand back then degrease and paint and then use proper lacquer like the 2k sort with high solids etc
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If its that bad, best course of action would be to cut it out. And weld new metal in.

 

If its just surface rust.

It really needs to be shot blasted to remove all traces of rust from the affected area. Then sanded back apply body filler if needed to fill in all the pits from corrosion. Then prep wise it will need and acid etch primer lightly applied over it. Then you need an epoxy primer as this will seal it of from, moisture and oxygen, as its this that penetrates the metal. but make sure the epoxy your using can be sanded and painted over, as some need to be rubbed down with out going through to baremetal, then a high build primer over it. Then prepped as you did before then painted, preferably with a decent 2k laquer.

 

There is no real cure for rust it will always come back unless you cut the affected area out and have it replaced, rust is like cancer on cars unfortunately.

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I believe acid etch primer is used so paint will adhere to metals which have been electroplated with zinc phosphate. 

Most, if not all modern cars are made of such metal, so is Zintec steel, which is used for repair sections.

 

As said, the acid within the etch primer eats into the metal to provide a good bond for paint.

 

I don't believe acid etch primer contains rust prevention properties.

 

Once a acid etch primer had been applied, to help with rust prevention, its best to apply an epoxy primer, then prep and paint as normal.

 

I've found a product, (which I've not yet used), which claims to contain anti-corrosion properties and is also an epoxy primer.

http://www.brunox.com/website/productpages...y-Spray-en.html

 

Rust converter products such as Kurust, don't actually stop or convert rusted steel into sound and rust free steel, they somehow seal the rust and a chemical reaction enables paint to be applied. 

The corrosion is sealed air tight and the chemical reaction slows down the corrosive process, quite drastically but it will eventually return.

 

It's impossible to prevent rust re-occurring to any body repair with a rust converter applied, it will more than likely, eventually return. 

 

However, if as much rust as possible is ground away, especially to the rear of the repair if access is possible, a rust converter applied, epoxy primer applied and prepped and painted as normal, this should be sufficient, but It's a judgment of  how long the car will be kept for, its value and how long the repair will remain rust free.

 

Best course of action is to cut out any corrosion back to good sound steel and weld in new sections and paint, however this may cost too much.

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I believe acid etch primer is used so paint will adhere to metals which have been electroplated with zinc phosphate. 

Most, if not all modern cars are made of such metal, so is Zintec steel, which is used for repair sections.

 

As said, the acid within the etch primer eats into the metal to provide a good bond for paint.

 

I don't believe acid etch primer contains rust prevention properties.

 

Once a acid etch primer had been applied, to help with rust prevention, its best to apply an epoxy primer, then prep and paint as normal.

 

I've found a product, (which I've not yet used), which claims to contain anti-corrosion properties and is also an epoxy primer.

http://www.brunox.com/website/productpages...y-Spray-en.html

 

Rust converter products such as Kurust, don't actually stop or convert rusted steel into sound and rust free steel, they somehow seal the rust and a chemical reaction enables paint to be applied. 

The corrosion is sealed air tight and the chemical reaction slows down the corrosive process, quite drastically but it will eventually return.

 

It's impossible to prevent rust re-occurring to any body repair with a rust converter applied, it will more than likely, eventually return. 

 

However, if as much rust as possible is ground away, especially to the rear of the repair if access is possible, a rust converter applied, epoxy primer applied and prepped and painted as normal, this should be sufficient, but It's a judgment of  how long the car will be kept for, its value and how long the repair will remain rust free.

 

Best course of action is to cut out any corrosion back to good sound steel and weld in new sections and paint, however this may cost too much.

Acid etch is just an adhesion promoter.

 

Why would you say, if as much rust as possible is ground away. To use a grinder would only achieve in making the metal even thinner, specially if done on both sides, which I definatly would not recommend. Which is why I recommend that it is shot blasted, as this will remove the corrosion and at worse will make holes, proving that the rust had penetrated all the way into the metal, showing it needs replacing.

To recommend an epoxy that you have never tried or know nothing about, and looking at it looks more like alot hype as it an aerosol product, I doubt very much its any good. Which is why a said it needs a 2k epoxy primer as it will work alot better I used correctly.

http://i760.photobucket.com/albums/xx242/Andyb0127/1c894329.jpg

Above is the epoxy primer i use as you can see its 2k product yes it's glasurit and will be expensive, but there are cheaper alternatives which will do the same job. Provided they are 2k and not aerosol.

Remind me not to let you attack any rust on my car with a grinder thinking that will do, sounds more like a bodge job from a back street garage.

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Andy, I was not contradicting your expertise, I sent my reply before your reply appeared, close to 5pm but for some reason my reply appeared after yours.

 

I never recommended the product, it was just a suggestion due to Kurust being mentioned, food for thought.

I've never used Kurust either.

 

Yes, Andy, everything you say and have suggested is correct, after all you are an expert in this field and do this for a living, you have answered my questions in the past too.

 

My suggestion to grind away as much rust as possible, was to remove the rust using a flap disc, then apply the rust converter as a preventative measure followed by a suitable epoxy primer.

 

 Although grinding away the rust does thin the steel, for a DIY'er and from my perspective, it's normally our only option, yes we may grind through but it's better to remove all traces of  rust, if possible.

 

If the rear of the repair is not attacked with the grinder too, rust that has formed to the rear of the repair area will eventually work its way through. 

 

I guess we're also imagining two different extremes of repair.

 

Shot blasting is definitely the way to go but due to cost or facilities availble, it's not always feasible.

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get an angle grinder with a wire brush on it!

Another alternative to that is 3m strip and clean wheels. Slightly over size for a grinder, but with the connector they fit yo will fit in an electric drill or air die grinder, or perhaps an air cut off tool.

Link below to said product.

https://www.google.co.uk/url?sa=t&sourc...UJIl3GwXBGbLy2Q

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  • 5 months later...
I can get hold of various chemicals from work, some of which we use to clean stainless steel etc, would this be any good for removing rust? Or would I just destroy the car...

 

Joe

 

It wouldn't destroy the car but it won't be killing rust either as stainless doesn't rust like ordinary steel

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