Hi.

I have been offered a bike with a 531 frame for a decent price. The trouble is there is some rust spots on the frame. How would I tackle this sort of rust in the least invasive way? I really like the colour of the frame so I would not want to attack it with too much vigour. I just want to neutralize it. I've been thinking of buying some Hammerite Kurust and just painting it over the rust sports. What do you think?

You won't like it, but at a minimum, you're going to have to scrape the bubbled paint off those spots, to get at the rust underneath.
Just painting over the lifted paint won't help.

Some more pics:

OK cool I don't mind doing that. as long as I don't have to take ALL the paint off.

I really like the colour. Am I weird? LOL

Sand blast the whole frame and then either paint it or take it to a powder coat shop and they will blast it and put a permanent finish on it. Roger

Scraping the bits of rust and leaving it is going to look far worse than a complete paint job, as with [MENTION=54042]rhenning[/MENTION] get it sand, or more likely media blasted, then you will be able to confirm if the rust is just on the surface (which it looks like) or if any tubes need replacing, than either get the bare frame painted or powdered, take your choice with the cost.

+1 on a complete strip and repaint if you like the bike well enough to justify the expense and the rust is still superficial. A paint shop or powder coater should be able to match the current color and replacement decals are available either from stock or custom made.

If this is just going to be a beater bike and you don't want to invest any significant money, treat the rust spots with Navel Jelly or a similar phosphate rust converter and touch it up with the closest color match nail polish you can find. It won't look very good but that's the best you can expect.

After seeing the rest of the photos, I'd have to agree with stripping and starting over.
You have what are called "worm tracks" under the paint - This is caused by a poor prep or material choice, when the bike was first built and painted .
If the bike's worth it to you, you may as well bite the bullet now, and re-finish -
If you farm it out, powder coating is usually cheapest - They can probably even match that color.

Yes, strip and repaint would be the absolue best (Powder coat would also work). However, it can cost a lot (IMHO). So it would depend a little on the end result you are trying to achieve. I'd be tempted to attack an area with rubbing compound to see if the rust and loosened paint will clean up. If that doesn't work, fine steel wool or sand paper on the end of a pencil or dowel. You can bring the fork and/or frame into a paint store or home depot and have an oil based enamel color matched. Others use nail polish or model paint. Of course, it will not perfectly match the sheen of the original paint and will be noticeable at a certain distance. When I was into cheap old motorcycles I used to rate them by how far away you had to stand to think "that's a nice bike". It might be have been a 5 foot bike or a 20 foot bike. This would be similar. If you want a collector, spend the money. If you want a presentable, functional bike without rust, try cleaning up the rust/loose paint and touch it up.

Rubbing compound will do nothing. You have rust creep under the paint. I'd either pass on the bike or plan some sort of repaint strategy. At minimum all the rust needs to be removed, including the rust under the spider web cracks, and then the paint patched. If you go this route there will be more rust in the future so be aware. A complete repaint would be best.

A full repaint is due.... powder coat the stripping to bare steel is part of the process... ask the same color be applied if you like it

you want to do an inadequate job.?
Sand each spot, down to bare metal,, then go with your touch up paint ... a zinc primer is a good idea.. (Done on Steel structures.. Ships, bridges.. )

Or, you could just ride it and ignore it.



Was there another thread about "worms under the paint"? That may have been a sign of serious damage occurring.

It doesn't look too bad from the outside, but it could be a reason to go with the full repaint.

This. And if you really like the color, take the frame to the paint shop before stripping it, and find the matching color. Then you can have a rust-free frame AND the color you want.

+1, if it is inexpensive enough and you want it to buy it and ride it... IMHO Very few bikes warrant a full strip and repaint because of the cost, yes powder coat may be cheaper but after you are done it is still a repaint...add the cost of consumables into the equation and you might be able to find a better original that does not need a full resto.
You will probably give out long before the frame does.
Best, Ben
I see SR says the same thing...

I would advise taking taking the BB out and checking there to see how bad the rust is.
Also should take the seatpost out and shine a light down the seat tube and inspect.

I had a Miyata that had rust like yours that I thought was surface rust.
Come to find out after wrestling with the seat post for hours and finally removing it, the seat tube
down by the BB was almost all the way rusted through. Barely anything left, frame was toast

Look up oxalic acid or electrolysis rust removal

Unfortunately, I don't think OA is going to get that rust under the paint.
If he scraped all the bubbled / worm tracked paint areas and THEN soaked it, then yeah, it would get it.
But the problem looks extensive enough, that he may wish he'd just stripped and re-painted -
To soak it, he'd have to dismantle the bike anyway.
Like others said, it's a judgement call - What's it worth it to him .......

And, electrolysis will definitely remove the rust, but it will also remove the paint, in most cases.

I would examine the inside of the frame as best I could. If it seems ok then treat the inside with one of the many framesaver products available such as boiled linseed oil, Boeshield, Weigl frame saver etc. Stripping and repainting is tedious but doable. Powder coating has worked well for me, too.