CaptainPlanet

I have a bike with chromoly 4130 frame, and there are some paint chipping and subsequent rusting on the frame, fork, riser, and handlebar. The riser and handlebar are probably made of some other material. I would like to try remove the rust and then paint over it with some primer rust paint combo.

When I looked up rust removal for bikes, the first results are always coke/vinegar with aluminum foils. Do they work for chromoly as well? Or should I stick to sander paper method that this forum suggested in other threads? Any other compound worth trying?

Hopefully with the screenshots of the rust in the album below I can get the info I need to make it work.

bikeforums.net/g/album/17610520

dsbrantjr

I would suggest taking off the heavy rust with sandpaper, steel wool or similar means, then using a rust converter to convert the remaining rust to a hard substance which will impede further rust and take paint well. Corroseal, Ospho and Evaporust are frequently recommended.

HillRider

The coke and/or vinegar (both weak acids) treatment is usually recommended to remove superficial surface rust from Chrome plated parts. For steel, including Cr-Mo steel, sanding followed by priming and painting is the better treatment. A rust conversion treatment of the bare spots before priming is useful but not essential is you do a good sanding job.

sced

Evapo-Rust works much better than vinegar in my experience https://www.amazon.com/dp/B00M0TLQ66/ref=emc_b_5_i

berner

Try it on corona virus. If it works you'll be a hero.

Iride01 

IMO, you don't have to remove all evidence of rust before painting. If the areas are large you can take a wire brush to it and knock all the loose off. Don't have to get to shiny metal. If it's just a spot or so here and there, then sand it to get rid of the loose paint and any scaly rust. Decent primer and paint will seal up and cover it for many years to come.

Automotive sanding primer can be used to build up areas that are lower than the rest of the surface around where you may have taken out a lot of old pant and rust. Wouldn't be a bad idea to clear coat all of that tube or part when you finish with your final paint color. They have all that and many colors in the touch up paint section at more auto stores.

davidad

https://www.nationalsupplydirect.com...SABEgIDIvD_BwE
Leaves iron phosphate that is like galvanizing. Then paint it.

bikebikebike

There is a Youtube comparing coke vinegar and Evaporust, that is amusing.
It has Good demonstrations that are pretty real world.
All three work.
Comes down to time and money.
Evaporust is pretty cost and time effective. though I would start with mechanical debulking of the corrosion and consider chemical removal an adjunct to that.

Andrew R Stewart 

When we were kids we needed a new washer installed. The service guy came out and after a short time in the basement he came upstairs and asked our Mother for some Coke. being the wise and frugal Mother she offered juice, water, milk, even her Earl Grey tea. he replied he wasn't thirsty but needed to remove the rust from the water connections. Andy

CaptainPlanet

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Should I get both rust remover and converter? Or just one of them will do and then prime and paint over them?

My local shops don't have evaporust, but they do have these in stock

Krud Kutter The Must For Rust, 946 mL, $15
local brand rust remover 236ml, $7
rust check rust killer 236ml, $11
rust check rust converter 236ml, $12

The only place I can find evaporust is online, and it ain't cheap, would cost me $30 minimum. They don't sell it in smaller containers.

I already have rustoleum rust paint, just need to decide which anti-rust strategy to go with.

Rust remover comparison, but I don't know how safe it is to use the more powerful ones. Is Krud Kutter more dangerous than Evaporust?
youtube.com/watch?v=6-MC_ZEXQbw

coffeesnob

And maybe President

sced

I bought a the 32oz container of Evapo-Rust on Amazon for less than $10 and did a bunch of small parts. Amazon sells a gallon for $20 with free shipping. I've used rust converters many times and the Evap-Rust makes them obsolete in my opinion. If you are going to do a whole frame I'd spend the $20 and rig up something to soak it, maybe a section at a time. Then you can finish the frame rust-free.

CaptainPlanet

Amazon only sells the 30 dollar Evaporust where I live, so I ended up getting Krud Kutter for 15. Feels bad for spending so much, but will see how it goes.

bikebikebike

PRODUCT SHOWDOWN! :
https://mechanicshub.com/toolbox/rust-remover-showdown-will-evapo-rust-prevail

This is what I had seen originally Tests coke, vinegar Muriatic acid , CLR, Evaporust and Krudcutter
More than you need to know ,but I have OCD and it is mother's milk to me
I won't cheat you out of the thrilling conclusion (at 10:00 in the vid)

sorry about the underlining, formatting never was my strong suit.

grizzly59

Oil, wd-40 etc., then elbow grease with a brass brush / fine steel wool. Clean it up, see what you got. Tubes are thin, gotta be careful with chemicals.

CaptainPlanet

Damn, I had a couple droplets of phosphoric acid (Krud Kutter must for rust) down the seat tube. Not a lot, but I didn't let it dry out before I put the seat tube back in.
Probably don't need to neutralize it with baking soda when a lot of people leave their frame in these things overnight and then rebuild their bike again.