Is this ok to high build primer over ?
Turbo Mini Forums

Hi I am about to paint the first coat of high build primer and I wanted to know will this little amount of surface rust going to cause problems later down the line . I used a wire wheels to remove most of the rust , thanks

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If you can see it, it will come back.

Kill the remainder of it with some diluted vinegar...

waving a flap wheel over it might be a good idea too...

http://www.ebay.co.uk/itm/10-X-FLAP-DISCS-...=item589d66205c

Thanks for the replays , I'm glad I asked now

The only cure for rusty metal is new metal. Doesn't matter what you do to it. It will rot again, then all your hard work is wasted.

I tend to disagree.

Rust is iron oxide. There is more than one type of Iron oxide.

The iron oxide most people know is 'red rust' which is also known as Ferric Oxide, has a chemical formula of Fe2O3 and is red in colour. This kind of rust usually forms as iron compounds are exposed to oxygen in the air and water, (whether as moisture also in the air). H2O + O2 + Fe react to give Fe2O3.

Black magnetite is also iron oxide, Fe3O4. This kind of iron oxide is a very good protective layer for iron which helps prevent Red rust forming when the iron is exposed to air. This is also known as pasivation and is achieved in a few different ways but usually results in the greying or blackening of the iron, 'black rust'. This creates a more stable iron oxide on the surface that protects the iron from the oxygen and moisture in the air.

So, as long as you have removed all the lose scale red and black rust and are left with the black marks deep in the metal, it should be fine when painted over since the whole point of the paint is to seal out the two elements that cause rust, yes that's right oxygen an water, keep those from the iron, and the 'rust problem goes away'. Of course the paint relies on adhesion to the surface, so if you don't remove all that scale from the metal the paint won't stick and you'll soon be back to square one. Also when the paint is applied, any moisture trapped between the metal and paint will still react with the iron and continue to produce black rust and again the paint won't stick and you'll be back to square one.

So the advice to 'treat' the area is good if only to ensure that the black marks beneath the red rust are truly converted to black rust (that is all the treatment does anyway) but be sure that the surfice is scale free.

The advice to cut out all rust is not practical since there is always a degree of red rust on the surface of iron since it is at least in part exposed to the air for a period before any paint is applied, unless of course you had the whole car dip passivated.

So, it is the paint adhesion you really have to worry about. It's the paint that stops the rust and if the paint doesn't stick.................

The whole car is covered with light surface rust . When I got the car I took it back to bare metal with a wire wheel, then I primed it but rust seemed to form on the surface. I've got all the rust off but there seems to be some black pitting in the metal

Edited by Jakej08 on 1st Jul, 2015.

Iv just seen sprockets reply and I was thinking the same thing , but I'm a novice when it comes to restoring a car

Rust can form oxigen in a sorth of form. (What ive been told) so once the process gas started it can only be slowed down... doesn't matter what you do metal will rust. If not now its in 10 20 or longer years... but it will rust.

you can do anything if you set your mind to it...
i rather blow it up winning than keep it together losing.

finish date set for project 1... march 2018

Iron and water without oxygen, such as would be the case with moisture trapped under the paint surface, react to produce black rust and hydrogen. The hydrogen helps the paint blister as the black rust scales the surface of the iron causing the paint to lose adhesion.

I'm not sure on the reaction of red rust in an oxygen free environment as to whether any oxygen is released, but I'd expect there would need to be some sort of reverse reaction for that to be the case....... is that even possible?

wel we did see a vacuum tube rust on the inside... how ever it can be speculated that it rusted trough the tube then... something intresting to thinck about

you can do anything if you set your mind to it...
i rather blow it up winning than keep it together losing.

finish date set for project 1... march 2018

It depends....

If it's genuine 'surface rust' that's happened because of a breakdown of the paint on the outside surface (EDIT: or bare primer which is porous), then remove all rust that you can, prime, fill, paint - Job done.

If it's spots of rust in the usual mini places like bottoms of the doors, wing to front panel joint etc, then this isn't surface rust as it's actually started on the back side of the panel and rotted through to the front. Even if you remove all trace of rust on the outside, it will bubble up in a few years. You can put some kind of barrier on the back to help slow it down, but new metal is the answer.

Which panel are you painting?

Edited by PhilR on 28th Jun, 2015.

Yes i moved to the darkside

Instagram @jdm_brett

Rust is rust. Cut it out and put god metal in.

Chances are you put cellulose primer in, which absorbs moisture...

Well, most people that paint cars that don't have the oven, will unlikely have a compressed air drier either, ergo you are painting the car with wet air anyway................

Etch it, paint it. Itll be fine

I seriously doubt it!