What can you tell me about Rustworm?

[retrobikeguy]

Or snakes under the paint on a steel frame.

Just considering a purchase and the Paint job is original, if I decide to go for it I would like to keep it original but it seems to have a few 'veins'.

Any info appreciated

RBG

 

[eri]

Some steel is quite hard, the rust will travel under the primer but doesn’t immediately damage the steel.

Bike I bought was less than 10 years old though. I took all the rust down to gray metal with a media blaster and glass bead. The 2” strands of rust made no impression but there was pitting under the blobby rust near the edges of the bb shell.

Bottom line it’s not something you can ignore. Media blast the rust away, spraymax 2k epoxy primer, then the best paint match you can find and finally spraymax 2 part clear.

The good news your amateur job can be redone by a pro in the future. You’re free to make your bike rideable.

 

[TreaderSteve]

My Explosif came with faded purple paint, some scabby bits and some worms as you describe. As the paintwork's too far gone (in my eyes) I rubbed-down those wormy bits and there was only light discolouration to the steel underneath - certainly nothing deathly to worry about.
I imagine it's the first stages of a breakdown in a paintjob - where moisture has got in and started to react with the steel - but only the beginnings. Keep such a bike in a damp shed/ put it away wet and then it'll get worse then scabby I suppose - but we treat our bikes better than that, don't we?!

 

[legrandefromage]

Snakes under Paint

Seems like a a good title for a film

Clean the areas and inspect because it may be internal too. Porous paint, dampness, rust.

This poor SBDU Maverick

 

[Tootyred]

Its moisture ingress under the paint. It often starts at junctions or fixings where the paint is not quite flat or is more likely to get hairline cracks due to expansion/ contraction or more likely damaged.

The moisture gets under the paint layer and as the metal beneath gets corroded it pushes the paint up.

Normally if you strip a rust worm frame you can see the lines of the trails in a discoloured line on the metal.

Home grown / poor quality paint jobs are particularly bad as the frames are often....

A. Not totally rust free when painted
B. Painted in an uncontrolled environment
C. Use paint of a lesser quality
D. Application is less than perfect.

You also see it a lot on things like zolotone, as its actually slightly porous! So it actively encourages the worms. Clear over bare metal is also bad as the protection of the substrate is obviously less from day one.

2k clear reduces this as imho, it has less shrinkage in use than traditional topcoats.

But basically its all down to good prep and workmanship......but then isn't everything .

 

[Tootyred]

Oh...and keep your bikes indoors at a constant dry temp and never get them wet...especially after midnight!

To fix, you could rub down areas, treat the rust and air brush in....then re top coat the whole frame after a quick light sanding. Its all i did on my red saracen.....

 

[madjh]

I have this problem in my Manitou Mach 5 fork. It is small but it has started. Sad, because it is mint.

 

[eri]

Also, I think I succeeded with a partial repair. I practiced on the stem that was to receive a full repaint. It’s pretty much impossible to properly strip with sand paper. It’s very important to strip all the rust and bad primer off the target metal, then clean, then primer. Mistake people make is to concentrate on the final appearance but the most important part is before the primer is put down.

Find a place that can media blast, or build a cabinet yourself.

In my case root problem was an innovative zero voc water based paint process from ppg that would fail 5% of the time.

Added more pix so you can see what grey metal looks like. Again once stripped you wash with thinner and then again with isopropyl alchohol. The epoxy primer takes 3 weeks to fully cure.

 

[brocklanders023]

What can I tell you? Had plenty of retro bikes with it and non have failed because of it.

 

[retrobikeguy]

What can I tell you? Had plenty of retro bikes with it and non have failed because of it.

And have you lived with it, or resprayed?