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  1. #1
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    Best way to clean frame/flux?

    Relatively new frame builder here. Im wondering if there are any better ways to clean off flux from a frame then soaking it for hours in hot water. Although this gets the flux off it leaves superficial rust all over and inside the frame and is a pain to get off especially in the nooks and crannies and inside the frame. Any suggest or alternatives besides soaking the frame or reliable ways to clean off the superficial rust? My frames look nowhere near this one from the sticky after cleaned ):

  2. #2
    Andrew R Stewart Andrew R Stewart's Avatar
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    You could wrap the fluxed areas with wet rags, the hotter the better. But this won't deal with the insides. You could add a bit of antifreeze to your soak tank. You could soak the frame in Evaporust after to remove the rust. I find that with GasFlux products I don't need hours of soaking. Silver flux takes only 5-10 minutes. Brass flux maybe twp or three times longer. The hotter the quicker. And if you keep the frame hot after the water evaporates faster and there's less rust starting. Finally the slight surface rust shouldn't be a problem unless you're doing a lot of other things wrong. Like using too thin tubes, not rust proofing after the paint job, riding in the ocean... Andy.

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    Hot water and time are about it as far as soaking. The problem areas are caused by too much heat for the flux and filler. The solution is more brazing practice and developing better heat control.

    You can use a brass wire wheel in a drill (please use face and eye protection) to clean up the problem areas.

  4. #4
    Old fart JohnDThompson's Avatar
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    I agree with Andy; Gasflux's paste fluxes are usually easily removed with hot water and a wire brush. Other fluxes can be quite stubborn. Sometimes tapping the blobs with a drift punch will shatter them and make them come loose, but it can be a tedious business.

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    Randomhead
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    the borax based fluxes don't come off very well unless the water is really hot. Gasflux and Cycle Design flux comes off really fast. I think that's the only way to improve flux removal unless you go to chemical means. That would require passivation and multiple dunk tanks. I assume that's not in the cards given the cost of even one frame-size dunk tank

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    The flux comes off but the problem has been what happens to the frame afterwords. How do i get rid of this orange rust and what to do about the inside of the tubes as well?

    0302141224a.jpg0302141224.jpg
    Last edited by NICBIKE; 03-02-14 at 01:47 PM. Reason: 1

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    Randomhead
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    the flash rust on the bb is no big deal. The dropout looks pretty bad, but it has so much extra material that paint prep should take that right off. I wouldn't worry about the inside of the tubes, just use framesaver after paint

  8. #8
    tuz
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    That's not a lot of rust, it'll come off easily.

    Cold water has more oxygen so it'll rust faster, plus flux comes off slower in it. Use hot water. Some people put anti-rust agents in the water; I've heard that molasses works well for that!
    homebuilt commuter, mixte, road and track (+ Ryffranck road)
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    So I didn't do too much wrong, that's good to hear. How would I remove those rusted spots though? getting around the BB and inside is quite tricky. Sandblasting? Thanks for the input guys

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    Quote Originally Posted by NICBIKE View Post
    So I didn't do too much wrong, that's good to hear. How would I remove those rusted spots though? getting around the BB and inside is quite tricky. Sandblasting? Thanks for the input guys
    Build the bike, soak it well, send it to your painter. He/she will have a process for dealing with the tubes inside and out.

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    In theory dilute oxalic acid will take the rust off and slightly etch the frame, making the paint stick better. I say in theory because I've never had the issue; I build with stainless steel tubing only.

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    Quote Originally Posted by Craig Ryan View Post
    Build the bike, soak it well, send it to your painter. He/she will have a process for dealing with the tubes inside and out.
    I plan on being the painter

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    Go over to the Classic and Vintage forum and search for Oxalic acid. They use it all the time with great results. You'll get all the information you need. Where to get it, how much to dilute it, how long to soak, before and after pictures, etc.

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    Quote Originally Posted by NICBIKE View Post
    I plan on being the painter
    In that case I'd just soak it really well, then worry about the outside and paint adhesion. The inside rust flash won't be an issue if you treat it with a product like framesaver. Short of a good soak tank and chemicals you can't do much for the inside other than that.

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    Thanks for the replies guys!

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