plonz 

I am entertaining an addition to the stable. The seat cluster area has a considerable amount of rust as pictured. Rest of the bike and cable guides look pretty clean.

How would this end up looking if I submerge just the cluster area in Evaporust? Totally unsightly or just kind of off? Any other thoughts?

And yes, I confirmed the seat post moves freely.

Nwvlvtnr 

You could try Naval Jelly, I’ve had some success mixing Naval Jelly and Evaporust. A method I’ve used on dropouts and fork tips that would likely work here would be to remove the seatpost and hardware then devise a method for securing the bicycle upside down so the the rusty seatpost collar can be placed in a shallow dish of Evaporust. Make sure the bike is sturdy and not going to fall over and ensure the whole of the rusty portion is submerged, this is much easier on a disassembled frame.

Schweinhund

Someone in another thread suggested that they soak a paper towel in vinegar and then wrap it around the rusted item and then saran wrap it.
It worked pretty good for me..

georges1

I use Rustol alongwith Evaporust

dddd

I had a similarly-bad situation at the upper headset, toptube and headtube area of a Miyata 914 I had purchased cheaply.
I used hot water to mix up a very concentrated solution of oxalic acid, at least ten times the recommended strength.
I used a tiny brush to apply the liquid over a period of a half an hour or so, re-applying as the liquid seemed to thin out or dry.
After that half-hour, the entire area looked great, there was no paint damage. and the remaining chrome on the headset (which was heavily rusted) looked shiny.

I really couldn't believe how well that this worked.

I did have a problem with some tiny bit of spatter that landed on top of my bare feet however, it became red and itchy almost like would happen if battery acid got on your skin!
So be careful about spatter and maybe just lightly spray off the bike afterward since the treated area needs to be rinsed anyway.
I flushed the area on top of my feet with water and lost no skin, so felt lucky about that!

The bike actually looked scary before I cleaned it up, due to the rust near a critical part of the frame. It had sat unsold in the racks of a popular co-op for years because of the rust, despite a low price and Superbe Pro hubs! I got the bike for a negotiated 80 or 100 dollars if I recall.

Oh, and even the shifter's hardware had blotchy rust residues, here are photos (sorry all are post-cleanup).

abdon 

I second the suggestion of using oxalic acid. It is cheap, comes in powder form, and mixed lasts forever. It is particularly useful for filling a large container for dunking large parts. I have one standing by for dipping anything rusty for when I need it.

There is no question whether it would work, there is no chance it will not. The acid react with the iron oxide and turns it into iron oxalate, which is a salt, which is easily brushed off. Works great on aluminum as well.

For grime have a separate bath of lye, sodium hydroxide. That doesn't attack rust but it will eat through the hardest buildup. Think cast iron skillet burned build up level of grime.

thinktubes 

Dunk in a small container of OA

gaucho777 

I would also 2nd the suggestion for oxalic acid. That seat cluster can be hard to submerge, but you should be able to pull the post and get the seat cluster area fully submerged with the right-sized (trough-like) container. You can also build frame or dig a hole and then line it with trash bags, etc.

Oxalic acid is commonly sold in powder form as wood bleach in most hardware stores. For frames, I use about 1.5-2 tablespoons per gallon and let it soak 24-48 hours. For small parts, I have a small soaking container that’s more like 4 tablespoons per gallon. Too heavy of a concentration (or forgetting that you have a frame soaking ) can leave a little film on the frame that needs to be washed/scrubbed off, especially if the surface area isn’t smooth. Wear gloves and use baking powder to neutralize when done.

After you pull the post, clean the excess grease inside the tube so the rust remover works at any rust inside the seat tube as well.

I’ve done the evaporust on a rag, wrapped in Saran Wrap. It works, too. But I find you’ll do a more thorough job with the oxalic acid and it may take a while for evaorust to work through some of the thicker rust buildup around the edge of the collar.

WT160

Where do you buy oxalic acid?

abdon 

Hardware store.

Charles Wahl

It's sold as "wood bleach" because that's one of its most common uses.

jdawginsc 

That's actually a good candidate for an evaporust bowl. It would make quick work of it and not have the hazards of OA. Just my opinion.

randyjawa 

I avoid using chemicals if possible for my bicycle restoration interests. This rusted chrome...



shined up just fine, not perfect, but pretty darn nice, in my opinion...




I was and soft brush the debris off of the chrome. Then I use crumpled aluminum foil to rub off the oxidation (rust), followed by a good cleaning and waxing. Not a show quality way to restore chrome but works good enough for this backyard mechanic. And no chemicals employed other that a few drops of dish soap.

plonz 

Thanks all. I should have been more clear I am interested in knowing what it will look like after treatment. Bare metal, gray, silver, black, etc? I’m guessing it will be a very pitted grayish color. This bike isn’t something I would have painted. Just trying to determine how unsightly the treated lug area will look.

oneclick 

(adding)
a) don't put steel and aluminium parts in the same oxalic acid bath - the ally bits get a dark smudge that can be hard to remove;
b) don't put ally bits in lye, they will get eaten away;
c) yes, big tank made of ply, lined with poly sheet, OA bath for the whole frame (does inside too).

abdon 

Compared to what? The unsightly rust? It would look a whole lot better.

trashbiker

What are you planning to do instead of paint? Its just going to rust again. Find a hobby store and get a matching color enamel. Bring a woman if you aren't one yourself. Women can see color better than men so you'll get a better match that way.

oneclick 

Some women (those with a single but expressed copy of a gene that results in anomalous trichromaticity) have four receptors.

plonz 

This hits on what I was getting at. After doing more research, I’ve studied up on rust converters as opposed to rust removers like Evaporust and OA.

Ideally, I’d remove the rust and use a converter that dries clear. A clear converter doesn’t seem to exist though. Just clear coating the area after using a remover may be the way to go.

Kabuki12

I removed HEAVY rust from an entire frame without using any of the chemicals mentioned above. Fortunately , the entire frame was chrome plated under the paint. I used a very fine steel wool with a dab of Mothers polish and a lot of time. Most of the paint was feathered away with chrome where there is no paint. I like the look after I finished and decided to leave it the way it was. I don’t know if it would have worked out as well on a non chrome plated frame. The exposed chrome areas had places that showed witness of the steel but the painted areas were still good .

As found after years left in a field in a Central Cal. Beach town

This is how it looks today, one year to get it riding again, two and a half years of pedaling and 100’s of miles!

oneclick 

The difference doesn't really matter unless you intend to not do anything to the surface afterwards (and as has been pointed out, it'll rust again).

Anything labelled "remover" is supposed to leave a surface of plain steel.
Anything labelled "converter" is supposed to change existing rust to a less friable material, bound to some extent with the base metal.
This converted layer should be removed before priming & painting (or powder-coating if you have no shame).
So you have to get to bare steel one way or another.

If you want to save as much steel as possible, use electrolytic de-rusting; a car battery charger, water and washing soda - no nasty chemicals, no work, and it only attacks the rust[1].
It changes the rust back to steel; though that is not bound (the rust wasn't, either) so you brush/wash the powder off before painting.

[1] make sure you get the connections correct.

cudak888 

OA on a paper towel. 2 hour soak.

Before:





During:



Progress:



Notice scaling remains on the paint, but it's still a lot more presentable than before:



After:



Also, since some of us are visual learners, this is what it looks like when I buy it locally: