Grinding Rust.

[nisfan]

Im currently working through the rust on my stanza and to keep it from getting worse in the winter, im just grinding out the rust with a flapwheel/knot wheel but what im finding is the rust coming back through after paint when i thought i had got rid of it.

Does anybody know the best way to totally eradicate it without cutting it out?

[PiperCub]

Flapwheels and wire type affairs tend to remove most of the rust but polish the remainder. There's two options, first is to do what you've done and get as much off as poss, then treat the whole area with a decent rust killer/converter, then paint, second is to use something like a Dremel grinder with a proper grinding stone to actually remove the metal the rust is stuck in. I'd still use a rust converter after anyway to be sure. 

I prefer the second method but the risk is you'll need filler to make up any 'hollows' left by grinding, not a big issue but another thing to do. 

[UltraWomble]

You could move to a planet with an oxygen free atmosphere  - I hear the Moon is quite nearby  - this will prevent any oxidisation.

 

Otherwise - rust treatment before primer & paint

[Uncle Jimmy]

All the cellulose primers I've tried have been porous to some degree so you can't leave anything without lacquering it.

The rust converters I've used have sometimes been a bit difficult to get paint to stick to.

I usually sand the steel really rough with 120 grit paper dry, gives it a good 'key'.

[mat_the_cat]

A chemical rust remover (not converter) will get back to shiny steel, including any pits you may not have mechanically removed. But as has been said, it could be down to paint porosity - any coating which dries by evaporation will be porous to some extent, where the solvent has evaporated from between the particles of pigment. With thick enough layers this is usually insignificant though.

[purplebargeken]

I use a selection of flap wheel, knotted wire wheel and polydisk when grinding off the brown stuff.

 

Agreed about pitting it is a PITA.

 

A good rust killer is what is needed. The best stuff by far has been made by Bilt & Hamber, deox something or other. Bloody good stuff.

 

I then coat with etch primer then red oxide. A couple of coats will do but make sure you leave it for at least a week before applying a second coat. You can then lightly sand to eradicate brush marks.

[stripped fred]

Agree, bilt hamber all the way. Have a look at products on their website. Not cheap but they work well.

[steveo3002]

i dont buy into the converters really

 

lash into it with your wire wheel and get it rust free as possible , then on with some bilt hamber deox gel , you paste it on thick and cover it and leave it to work , rinse off and repeat until its all clean silver steel which might 3-4 goes , even a tiny pit will be back

 

then on with epoxy primer idealy...if not then etch/paint but dont allow primer to  be in the wet as it will absorb moisture

 

having said all that ....alot of times its rotting from inside and the only way is cutting it out , might not be what you want to hear but thats how it is , you need to do whatver you have to fully remove the rot , theres no magic lotions n potions to save the hard work

[dollywobbler]

Zinc primers can help, and some are thick enough to effectively act like a skim of filler to help smooth out any pitting. As per the above post though, if a box section has started rotting out from the inside, it doesn't really matter what you coat the outside with. It'll still rot.

[sierraman]

Grinder with a wire wheel on it, then some rust converter on it. Fill it then paint. It just depends what you are expecting. If its tidying the arches up on an old Cavalier or something then do above and it should stave it off for 2-3 years. Non cosmetic areas, I'd do the above with the grinder, then rust converter, then paint zinc primer on 2-3 coats, followed by some shutz. You could really go to town with buying this that and the other but unless you're embarking on a restoration or something you are likely wasting money.

[D Spares & Tyres]

Sandblasting is the only way to eradicate it properly

 

You can get a reasonable home kit for £200 or so

[Tamworthbay]

Bilthamber deox c gel is your friend here, apply, cover in cling film and leave, repeat if it's deep and you end up with a chemically clean surface. If you were close to me I could give you some in a jam jar, you don't need much.

[HillmanImp]

I use Deox C too but the paint. I always remove all rust, Deox C it and then put on some paint on the non exposed side before welding. Once welded in, I always then do the same on the outer side as I go along so that it spends as little time as possible exposed to the elements. When I see people welding already slighty rusty metal onto their cars, and then simpy wanging some protector and waxoyl over the exposed side, I am sure it wont last long as was always told that it will rust from the inside out as the rust is already there and will just grow.

 

I realise that I will burn off a lot of the paint etc on the non exposed side when doing the welding but its got to be better to start off with as good a situation as possible isn't it, surely?  

 

Either way, thats always worked for me.

 

When painting properly, as mentioned above, primer is porous as it obviously needs to absorb the top coat so I have always tried to not leave it exposed too long.

[forddeliveryboy]

I use etching primer, it works better than anything else for me, but I haven't tried the paint someone linked to on the forum a few months ago which is used on steel pipes under the North Sea.

[sierraman]

It all depends what you are doing. As I say if it's patching some old Focus to get it through its test id still not plate over the rust, I'd get it cut out then let new metal in but all the same I'd be realistic as to how long the rest of the car would've expected to last, hence I wouldn't go mental trying to make sure it never rusted ever again, when something like a clutch goes in 6 months time and you end up binning it anyway.

[vulgalour]

Rusty Nissan?

 

 

[mercrocker]

The oil rig stuff I think is Vactan. I use this successfully after testing it on a rusty horseshoe which I left in the open for 2 years after treatment. The good thing about this stuff is not only does it seem to work but it doesn't need washing off.

 

Bilt Hamber zinc-rich primer is also recommended - it can be left uncoated and again I can vouch for it after treating under the Minor a year or two back. I forgot to go back to one area which had been treated/primed but never top coated. It looked as good as the day I did it so I just went over it with POR15.

 

I am never sure about the efficiency/necessity of using a zinc rich primer on top of a rust treatment but the combination of Vactan plus Bilt Hamber plus a decent couple of topcoats has so far appeared to keep the rust at bay....

[nisfan]

Ok in the past i have used a flapwheel and then rust remover (jenolite) , the rust came back.

I have found that doing it in the summer does help as there is probably less moisture kicking about.

Ive know of bilt-hamber stuff and am happy to use it on my bluebird but the stanza would need a barrel load of the stuff, im painting it with the aldi paint that was talked about on here before, its merely to keep it getting worse but seems to come back after 2 weeks! Mind you its out in the open in scotchland so i should expect it.

I know the best thing is to cut it out bet there would be nothing left!

[steveo3002]

well if its coming back so soon youre either not removing enough brown stuff and/or its festering from inside out

 

theres no magic cure it...either knuckle down and remove every last spec or accept its a half arsed job and wont last 

[vulgalour]

Can you hammer a smaller Nissan over the top of it?

[Tamworthbay]

Forgot the turkey, gt the side of an old washing machine, a mig, cup of tea and sort it properly if it's that bad.

 

 

Or you could bridge it..........

 

 

I'll get my coat.

[Bobthebeard]

If rust is in a non structural area, and welding is not available just cut out the rot and use fibreglass bridging stuff. If used sensibly and properly the 'repair' can last for years. Plenty of 'how to' videos on youtube. Just cut out all the rust and lather on the resin. It is surprising how resiliant this kind of bodge can be if done properly. No guarantees obviously, but if in A NON STRUCTURAL BIT it can work and can last for ages.

[derskine]

I think it's just the Datsun curse... even the 18 which was kept in the same unit, didn't display such non rust resilience...

[sierraman]

I once had a fiesta wheel arch repair made from some lolly sticks, chicken wire and filler last 3 years. Did the job but I'd hardly recommend it.

[vulgalour]

I'm with Bob on this one, a repair done with not-metal to a good standard is a perfectly acceptable solution.  Race cars have metal decorative sections replaced with not-metal sections so why not a road going car?  Providing the repair is done well with good preparation and it's not a highly mobile or structural panel then there really isn't a problem.  Just make sure whatever you use isn't porous so moisture doesn't get in and make a bigger mess of the repaired area.

 

Alternatively, remove the rust, treat, paint and apply a tidemark of underseal.

[fordperv]

So ford had competition in mind with their rust design. They knew people would save weight by repairing chassis legs and sills with pages from the sun papier mached to shape covered with underseal

[sierraman]

Or, here's my favourite, any holes less than about 1/2 inch diameter, smear tiger seal into then coat thickly in underseal.

 

There was a chap near us he used to rivet old road signs - the thin galvanised type, over holes. I'd stop short of that, if it's structural it wants a shake with the welder.

[Split_Pin]

Hey, there was a video on you tube of a guy, and with not a whiff of irony, ground out all of the rust on a prescribed area of the front chassis leg on a Corsa, treated the now large hole, sprayed anti rust product on it and then put big swathes of fibreglass matting on it!!!!

[mat_the_cat]

I am never sure about the efficiency/necessity of using a zinc rich primer on top of a rust treatment

 

The zinc needs to be in electrical contact with the steel to have any benefit over and above simply a protective layer of paint, so a layer of converted rust will actually isolate the steel from the zinc. As an experiment, back in Spring this year I painted straight over some rust on the roof of the bent Disco with some Zinga. This has a lot more zinc than a zinc rich primer (~95% or so - it feels very weighty in the tin) and although it doesn't convert any of the rust, the zinc will oxidise before the rust in theory, so should stop it from getting any worse. I deliberately wanted to try it over rust rather than clean steel, to give a tougher 'real world' kind of test...

 

I was going to leave it a year before reporting back, but seeing as it's relevant to this thread I'll post up some pictures tomorrow. Here is the thread:

http://autoshite.com/topic/18079-disco-fever/?p=760258