Removing rust from an old steel frame

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Ukerola
Posts: 1
Joined: 22 Oct 2019, 11:49am
Location: North Bergen

Removing rust from an old steel frame

Postby Ukerola » 22 Oct 2019, 11:51am

I have an old steel (531) framed bike which has some rust spots.

What should I do about them? From a quick google it seems that the correct strategy is to clean off the rust (e.g. aluminium foil - does this really work?), sand down the area, then spray with automotive paint. I can knock the frame to check for a 'dead' sound to work out if the rust is structural. If it is, then I need a new frame(set).

Any advice on this, or is the above a 'plan'? If I'm not sanding down the entire frame, just spots, then there must be edges around the sanded area. What happens when I spray paint around them? I think that stripping the entire frame is beyond the time that I can afford to spend on this.

hamster
Posts: 3497
Joined: 2 Feb 2007, 12:42pm

Re: Removing rust from an old steel frame

Postby hamster » 22 Oct 2019, 3:17pm

It all depends on the extent of the rust.
If the frame looks awful with large areas of flaked paint, then take it to your local powdercoater: they will blast and repaint it for around £50-70. If there a few bike frames around, then so much the better as they will know how to do bikes well (most do these days).
If you want it looking lovely, then a specialist frame painter like Bob Jackson, Vaz or Argos will do it for £100-150.

If it's minor rust areas, I rub back with a car stone chip kit, prevent rust return with a coating of Kurust, then prime and touch up.

Brucey
Posts: 39500
Joined: 4 Jan 2012, 6:25pm

Re: Removing rust from an old steel frame

Postby Brucey » 22 Oct 2019, 6:31pm

aluminium foil is a bodger's delight; it scrapes loose rust from chromed parts and what it doesn't remove it turns silver-coloured for at least five minutes. It is not the method that is to be used on a 531 frame.

Realistically you can't tell if thin-walled frame tubes are corroded to the point of failure or not; remember that they are as thin as 0.5mm in places in some 531DB tubes, which isn't much steel to start with. All you can do is refinish the frame, ride it, and check it for cracks in use.

If you want good advice about how best to treat the rust patches you have, then it is best to post photos.

FWIW if you are after a quick solution, repainting small areas piecemeal ain't it.

cheers
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David9694
Posts: 577
Joined: 10 Feb 2018, 8:42am

Re: Removing rust from an old steel frame

Postby David9694 » 22 Oct 2019, 7:32pm

400 grit wet and dry paper and an awful lot of elbow grease. It’s all or (nearly) nothing with painting if you’ve large areas of superficial rust. The DIY route is a labour of love, to get the whole frame smooth, cleaned, then primed, then top coated, and clear coated, rubbed down between coats, all at a time of year where the elements are against the outdoor rattle-can sprayer. But l’ve had fun in my back garden with different paint schemes (e.g. contrast head tube, seat tube, pearl, metallic, “coach lining”) and decals.

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Gattonero
Posts: 3730
Joined: 31 Jan 2016, 1:35pm
Location: London

Re: Removing rust from an old steel frame

Postby Gattonero » 23 Oct 2019, 8:07am

Rust creeps from sharp angles, like braze-ons of cable stops and the likes. If you see a light nervature under the paint is probably not too bad, but if those are thick and bubbling then you really need to strip down the paint to see the extent of the damage.
To respray a frame is always a good thing, if you can make most of the work of stripping down&rebuild the bike, it will save a good chunk of money and make it very worthwhile.
It is by riding a bicycle that you learn the contours of a country best,
since you have to sweat up the hills and coast down them.
Thus you remember them as they actually are...

cycle tramp
Posts: 743
Joined: 5 Aug 2009, 7:22pm

Re: Removing rust from an old steel frame

Postby cycle tramp » 23 Oct 2019, 7:18pm

This year I tackled a very very rust tubus rear rack by rubbing down all rust patches,, treating with a rust converter, two coats of red oxide primer, rubbing down again between each coat, then two coats of fergusson grey, brush painted.... the paint finish is best described as theft resistant... but at least I won't feel too bad about re-touching the paint when it wears :-)

gbnz
Posts: 1761
Joined: 13 Sep 2008, 10:38am

Re: Removing rust from an old steel frame

Postby gbnz » 27 Jun 2020, 3:14pm

Brucey wrote:
Realistically you can't tell if thin-walled frame tubes are corroded to the point of failure or not; remember that they are as thin as 0.5mm in places in some 531DB tubes, which isn't much steel to start with. All you can do is refinish the frame, ride it, and check it for cracks in use.

FWIW if you are after a quick solution, repainting small areas piecemeal ain't it. s


What about Reynolds 725 tubing?

My 5 Yr old, handmade English steel touring frameset from a well known supplier has developed rust under the paintwork at a no. of the lugless joints, the rust having mildy broken through on one or two patches. I'm presuming it's due to the sub standard paint finish, the paint having largely failed over the frame (NB. The bikes done a minimal mileage, never been used for daily commuting, had minimal winter use, has always been stored in a dry, indoor environment)

I don't want to waste money on a dodgy frame so my gut reaction is simply to do a light sand and paint by hand (NB. I've a part used tin of black metal paint). Is this likely to keep the rust at bay? (Nb. There's no sign yet that rust is originating from the inner surface of the turbing)

Brucey
Posts: 39500
Joined: 4 Jan 2012, 6:25pm

Re: Removing rust from an old steel frame

Postby Brucey » 27 Jun 2020, 3:45pm

725 tubing is available in different gauges, so depending on the frame's purpose and the builder's preference you could have different tubes from another 725 frame.

IME it doesn't take much winter use to destroy the paint finish on some frames; a common problem is that if winter road salt is not washed off the bike immediately, it will be merrily corroding the bike even in supposedly 'dry' storage. The best looking paint jobs are thin, sprayed wet and don't ever provide a completely impervious barrier to road salt-induced corrosion; typically the frame 'breaks out all over' as you describe and this is difficult to distinguish from a frame that has been badly prepared before painting. Powder coating is less prone to this type of failure but looks worse when it is new and can lift and fail at any exposed edges, where chipped etc. Horses for courses.

You can carry on patching up a paint job 'gone bad' for a very long time but if corrosion is active beneath the paint it may not do any real good and you are fussy about the appearance of the bike it probably won't make you happy either. Time for a respray, probably.

cheers
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