Advertise on Bikeforums.net



User Tag List

Results 1 to 11 of 11
  1. #1
    Senior Member
    Join Date
    Sep 2005
    Posts
    3,310
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Stupid mistake - final soak too hot, surface rust - help me treat it?

    Sorry for the length. I'd appreciate help.

    The problem:
    I just finished a frame building course, and soaked the frame to get rid of some big hunks of flux, and the water was too hot. Now, there are little wisps of rust all over the down tube and bottom bracket.

    It's coming off easily with 220 grit, but I'm worried about the inside tubing, where the tubes were prepped for brazing. I'll have it painted in a few weeks, they can probably take care of it, but I want to stop the tiny bit of rust now if I can.

    My plan:
    I picked up some 'Krud Kutter - The Must For Rust' at the hardware store. (It was a choice between this and Naval Jelly, and since I'm trying to treat the insides of tubes I figured the more liquid, flowing stuff would work better.)

    I'll sand off most of the outer rust, and then treat some place inconspicuous - i.e. the inside of a chainstay - to see how this stuff works. Then, get set up with a big bin and a big water bottle with some sort of thin nozzle, spray a bunch of the Krud Kutter into a tubes, wait a decent amount of time, then rinse the snot out of it with room temperature water - through the water bottle braze-ons / bottom bracket drain holes. Probably do one tube at a time.

    Will this work?
    Anyone have better advice? Thanks in advance.

  2. #2
    Randomhead
    Join Date
    Aug 2008
    Location
    Happy Valley, Pennsylvania
    Posts
    12,560
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    don't panic, happens all the time. I wouldn't even mess with it. If you're really worried, get some metal prep. Just tell the painter what you've done.

  3. #3
    Senior Member
    Join Date
    Sep 2005
    Posts
    3,310
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Ok, cool. Thanks. I'll stop stressing and just work on smoothing out the brazes. LOTS of bronze I can focus on there instead.

    Any brand of metal prep stand out for you, or is it all the same?

  4. #4
    Randomhead
    Join Date
    Aug 2008
    Location
    Happy Valley, Pennsylvania
    Posts
    12,560
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    there are many brands, get some that is meant to be painted. I have never bought any.

  5. #5
    Senior Member mudboy's Avatar
    Join Date
    Sep 2008
    Location
    Collegeville, PA
    My Bikes
    Ruckelshaus Randonneur, Specialized Allez (early 90's, steel), Ruckelshaus Path Bomber currently being built
    Posts
    1,353
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Personally, I wouldn't worry about it, the frame should get media blasted on the outside before painting, and then just use some frame saver on those tubes that aren't sealed after you get it back from paint.

    With that said, soaking the entire frame is a bit excessive, I just use the hot water from the spray nozzle on my kitchen faucet to wash the flux off, hitting it with a brass brush, and that does the trick. It also helps me avoid getting too much water inside the frame...some is normal, especially in the BB.

    Pete
    --~--~--~--~--~--~--~--~--~--~--~--~--~--~--~--~--
    Ruckelshaus Randonneur • Ruckelshaus Path Bomber
    Flickr Photostream
    FrameBuilderSource.com Framebuilder Database

  6. #6
    Randomhead
    Join Date
    Aug 2008
    Location
    Happy Valley, Pennsylvania
    Posts
    12,560
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I have a large bowl that I fill with hot water, saves a lot of energy
    Brass flux takes some soaking in very hot water to remove.

  7. #7
    Randomhead
    Join Date
    Aug 2008
    Location
    Happy Valley, Pennsylvania
    Posts
    12,560
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I will admit to running the hot water when I am in a hurry though.

    i was looking at Engin Cycles' pictures, and I found this
    I'd rather it not happen just because it means more cleanup, but it happens to the best of us.
    Last edited by unterhausen; 04-26-10 at 03:50 PM.

  8. #8
    Senior Member
    Join Date
    Sep 2005
    Posts
    3,310
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by mudboy View Post
    With that said, soaking the entire frame is a bit excessive, I just use the hot water from the spray nozzle on my kitchen faucet to wash the flux off, hitting it with a brass brush, and that does the trick. It also helps me avoid getting too much water inside the frame...some is normal, especially in the BB.
    I was just following Mr. Yamaguchi's advice.

  9. #9
    Senior Member
    Join Date
    Sep 2005
    Posts
    3,310
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by unterhausen View Post
    I will admit to running the hot water when I am in a hurry though.

    i was looking at Engin Cycles' pictures, and I found this
    I'd rather it not happen just because it means more cleanup, but it happens to the best of us.
    Oh man that's super excessive. I think I'd faint if I ever saw that.

    Nope, this is just a dusting. Like a pinch of talcum powder here and there.

  10. #10
    THE Materials Oracle Falanx's Avatar
    Join Date
    Feb 2006
    Location
    Finally... home :-)
    My Bikes
    Univega Alpina 5.1 that became a 5.9, that became a road bike... DMR TrailStar custom build
    Posts
    502
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by schnee View Post
    Sorry for the length. I'd appreciate help.

    Anyone have better advice? Thanks in advance.
    Yes, I do.

    STOP using abrasive means to remove it at all.

    Go to your local health food store, or such and buy a tin of blackstrap molasses. Dissolve the contents of the tin in nine times as much water and soak the whole frame in it.

    I know it sounds a little bizarre, but basically, there are a number of complex acids in molasses that chelate iron (ii) and (ii) ions, and will eat the rust off the frame, all the tubes, inside and out but because the sound metal underneath isn't penetrated or pitted, won't cause crevice corrosion or cause the rest of the sound metal to corrode.

    On an object bike-frame sized, you'd need a large vessel, big enough to submerge the whole frame. and then some, so that you can agitate the water and ensure none of the solution becomes stagnant inside the tubes.

    If you want a practical demonstration, the find a couple of rust bolts or nuts and treat them in a jam jar with the same strength of solution - 9:1.
    "While my father fought for you, I learnt. While my father glorified your petty administration, I learnt. While he longed every day for our line, Adun’s line, to be restored, I learnt. He sent me away to bring the Dark Templar back when the time was right!
    "And you tell me that I cannot do this? That I cannot feel the weight of the universe?
    "Damn you, Tellan! Aldaris killed my father!"

  11. #11
    Senior Member
    Join Date
    Sep 2005
    Posts
    3,310
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    That sounds awesome. Thanks.

    FWIW I'm leaving the rust alone and focusing on sanding down the joint brazes. I'm calling the painter later on today (funny enough, Yamaguchi's main painter is local to me in San Diego) and ask their advice. If they want me to treat it before I bring it in, I'll give that method a shot.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •