Body & Rust Repair process & Products

[Jon Brown]

Hi all

I have been using google but couldn't find exactly what I was after, so I thought I would turn here as usual.

Last year my classic mini was repaired, prepped and painted by 'professional' who completely cocked it up and now have rust, orange peel and fish eyes all over my paint.

I don't want to get into what they did wrong and claiming etc but just want to fix some of it myself as I can at least control the quality (to some extent) and make sure the right process is followed (ie actually adding seam sealer!)

So from a process point of view:

Rust removal, I can get back to bare metal in the required places (either blasting or wire wheel) but what is the best stuff to treat the rust to avoid it coming back?

Once that's done, do you etch prime before seam sealer?

It will need some small amounts of filler work here and there, what's the best type of filler and is it best applied to bare metal or etch primed or other type of primer first?

For areas such as sills and wheel arches I know there are a number of options but again its the order i'm not sure of or what's the best product but would like colour coded arches and sills

I have a compressor and can get a spray gun, most of the areas wont be seen.

Are there any comprehensive guides or tips that anyone can point me too?

thanks
Jon

[droopsnoot]

Jon Brown said:

Rust removal, I can get back to bare metal in the required places (either blasting or wire wheel) but what is the best stuff to treat the rust to avoid it coming back?

That's a bit confusing, I read bare metal as clean metal, so at that point there's no rust. So if you then prime and paint, that should be it.

Jon Brown said:

Once that's done, do you etch prime before seam sealer?

I did on mine, but it's too early to say whether that's correct or not. I figured I wanted something under the seam sealer in case water somehow gets behind it, though the manufacturers (80s Audi and 70s Vauxhall) seem to get away with not bothering.

Jon Brown said:

is it best applied to bare metal or etch primed or other type of primer first?

I put epoxy primer on prior to filling. The problem usually is if the primer behind the filler shrinks, it can cause "tide marks" around the filled areas that are visible through the finished paint. Epoxy isn't supposed to shrink, mine hasn't been done long enough to say how it lasts.

Jon Brown said:

Are there any comprehensive guides or tips that anyone can point me too?

I'd have a dig around sites like Retro Rides - I've been watching a thread in "Readers Rides" on there about the restoration of a Ford Corsair and it's just been painted. It's being done by someone with a lot of experience and pride, but he also doesn't mind stopping to explain bits to the rest of us.

[GTVOX]

I've done a lot of cars so here's my experience with what has worked for me :

Etch Primer should only be used on bare metal. It can sometimes cause a reaction with other primers or filler, so if you've managed to sandblast that should be OK. I use Bilt Hamber Products their Rust Remover is excellent as is there rust converter. I've also used Flag's rust converter which was very good. They leave a black surface which can be primed and then painted. Although it says you should only use on rusty metal I've found that it leaves a great protective coat especially if you warm the area with a hot air gun. 2 pack epoxy is excellent particulary for the underside.

I always use a 2 pack primer/filler on the bodywork after any filling and on top of epoxy or etch primer. Once cured it can be sanded back to leave a perfect surface for the top coat. It will not usually shrink back once sanded flat. It's that good it can take out shallow dents and imperfections.

With primers you want to keep the surface fairly rough I normally go to around 320 grit then give a colour marker coat which I flat back with varying grades up to 6/800. It all depends on the quality of paint you use as there is no consistent solution it's more my experience I'm sure others will have different views but it's what works for you.

[Jon Brown]

Thanks chaps this is really helpful.

The first issue on the car to sort is the front and rear valance, the useful part about the mini is that this can be done in isolation to the rest of the car.

That’s a start anyway, also got the engine bay to tackle when the engine comes out again, although likely to be a while til I get there.

I guess like you say it’s largely experience but need to start somewhere so this really helpful

[dartissimus]

Have you tried looking at Youtube

"Mollasses Rust Removal"

[Astacus]

This is my 2peneth based on may years of tinkering with old cars.

Wire brush is excellent for getting rid of rust on panels, but only the knotted/twisted type you use on a grinder. The others are useless. Don't be tempted to leave it at that though, because there is always a trace of rust you cant see. You should always wipe clean and treat the surface of the panel with a rust converter like Kurust. If you still have some pitting with rust visible the converter really wont stop it coming back in my experience. The only de ruster I have really had good results with is deox-C from Bilt Hamber. I think there are others now, but this is the one I stick with. They do it in a gel form as well; leave over night covered in cling film then wash off. Repeat until the metal is clean, you have to apply generously though. I did a steering rack like this, by covering in cling film, washing re treating until it was done.

If you use their powder in water treatment, you can speed it up by using boiling water from a kettle instead of tap water!!

Rust in seams will always come back....there is no escape.

If you aren't painting immediately then a quick coat over with primer can protect for a while, but don't leave it too long before you over paint otherwise it will all come back again.

[droopsnoot]

Astacus said:

The only de ruster I have really had good results with is deox-C from Bilt Hamber. I think there are others now, but this is the one I stick with.

I've used Deox-C for soaking parts in, and I'd agree that it's very good. I did, however, also try Citric Acid powder which is available quite easily on line, or I saw some on the TV the other day that suggest it's available from shops as well. I suspect, but cannot prove, that Deox-C and Citric Acid powder are the same thing - they look the same, dilute the same, produce the same results. The only difference is Citric Acid powder isn't packaged, so it's a lot cheaper.

I didn't try applying it to parts that cannot be soaked, though I did hear of the cling film solution to stop it evaporating before it does its work.

[Jon Brown]

Thanks chaps more useful hints, not particularly inspiring that you can never really get rid of the rust though

[tapkaJohnD]

Rust will react will any acid, and the "strong" acids will of course react with the original metal! Organic acids are a better choice, and citric acid as good as most, IF you intend to quickly protect with a primer. It leaves bare metal, which is prone to flash rust in minutes.

Better is phosphoric acid, because iron phosphate is insoluble in water and will remain on the surface. When dry, it provides a good substrate for paint, and will prevent flash rust.

Phosphoric acid is the basis for all rust treatments that make it turn black! Buy it online, or at a farmers' suppliers, where it is sold as "milkstone remover". its harmless, used as a food additive (the 'bite' in Coke!) but should be used with all precautions, eye and skin protection.

John

[alabbasi]

My professional opinion (as a software guy):

Media blasting will de-rust all the metal you can see but it's not going to get into the box sections. Chemical dipping remove all rust but be prepared to have a shell come back looking like a t-bag.

Epoxy primer on bare metal because it seals the metal and sets up like rock. Plastic work needs to be done on the bare metal and you can use a glaze on primer.

Forget about restoring a car for daily driving, if you want it to last, you can't bring it in wet weather where there's salt on the road. You have better odds of finding a car in a dry state and re-shelling what you have.

[Astacus]

droopsnoot said:

I've used Deox-C for soaking parts in, and I'd agree that it's very good. I did, however, also try Citric Acid powder which is available quite easily on line, or I saw some on the TV the other day that suggest it's available from shops as well. I suspect, but cannot prove, that Deox-C and Citric Acid powder are the same thing - they look the same, dilute the same, produce the same results. The only difference is Citric Acid powder isn't packaged, so it's a lot cheaper.

I didn't try applying it to parts that cannot be soaked, though I did hear of the cling film solution to stop it evaporating before it does its work.

Yes, I was wondering that too except that it does also leave a black deposit, so I think it might also have some phosphate component