backing on patches

Discussion in 'General Cycling' started by Adam Funk, Sep 11, 2011.

  1. Adam Funk

    Adam Funk Guest

    Most patches come with a foil layer on the tube side and a thin,
    fiddly, plastic layer on the side that will end up facing out. The
    foil is easy to remove, but the plastic isn't. A page by Jobst Brandt
    on Sheldon Brown's website says:

    The backing paper or cellophane often has perforations so that it
    will split in half when tube and patch are manually stretched. This
    makes peeling the cover of the patch from inside to outside
    possible and prevents peeling a newly applied patch from the tube.

    http://www.sheldonbrown.com/brandt/patching.html

    but I generally find it fiddly. What's the reason for putting that
    plastic layer on patches?
     
    Adam Funk, Sep 11, 2011
    #1
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  2. Adam Funk

    Tosspot Guest

    It's to protect the feathered edge and make it easier to seperate the
    patch from the foil. I've found the perforations often missing and
    either score the cellophane of just leave it on.
     
    Tosspot, Sep 11, 2011
    #2
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  3. Adam Funk

    Adam Funk Guest

    I was hoping it wasn't just a fiendish plot to wind me up. Thanks.
    :)
    If I need to use the patched tube right away, I leave the plastic on too
    (and peel it off next time the tube is out), but normally I inflate a
    patched tube several hours later outside the tyre to check my work,
    and sometimes the plastic loosens up then.
     
    Adam Funk, Sep 11, 2011
    #3
  4. Adam Funk

    thirty-six Guest

    Burnish the patch by rubbing through the plastic and it will fall
    off. Testing patches may lead to their failure. The chemical bond is
    not considered complete until at least 24 hours. It's best not to
    play with them unless you are disposing of the tube anyway.
     
    thirty-six, Sep 12, 2011
    #4
  5. Adam Funk

    Adam Funk Guest

    If I don't test the patch, there might be another (smaller) leak in
    the tube.
     
    Adam Funk, Sep 12, 2011
    #5
  6. Adam Funk

    Dennis Davis Guest

    To further quote from Jobst Brandt[1]:

    That's why the cellophane is split in the middle... so you can
    peel it from inside to outside of the patch periphery with no
    lift-off. This is done by manually stretching the tube and patch
    so the cellophane breaks across its barely visible perforations
    and lifts in the middle. Cellophane is not stretchable and should
    be removed to allow the patch to elastically cover the puncture
    area.

    Aluminum foil is used to keep the 'red' side from losing its
    adhesive quality through evaporation. Cellophane does likewise
    but being less impervious, is on the back side of the patch where
    it is good enough. The foil is easily removed by bending down a
    corner by which the cellophane remains flat and allows pulling the
    patch from the foil. Do not cut off the corners because they are
    there to lift the patch.

    As others in this thread have noted, the perforations often seem
    missing from the cellophane. No problem, you normally have a little
    time to wait while the applied rubber solution dries enough to apply
    the patch. At this point I remove the cellophane by folding the
    patch in half. The cellophane usually splits across the middle and
    can easily be removed before the patch is applied.

    I also believe removing the cellophane is an aid to curing the
    patch, as it allows the rubber solvents in the glue to permeate more
    easily through the patch.

    [1] http://yarchive.net/bike/inner_tube_patching.html
     
    Dennis Davis, Sep 12, 2011
    #6
  7. Adam Funk

    Rob Morley Guest

    Hah, we agree on something. :) After sticking a patch I lay the
    tube on a hard flat surface and rub the patch hard with the rounded end
    of a plastic tyre lever to ensure good contact. That usually splits the
    clear backing and makes it easy to peel off later, after the repair has
    had a chance to cure.
     
    Rob Morley, Sep 12, 2011
    #7
  8. Adam Funk

    thirty-six Guest

    Or not. Test it in the wheel/tyre.
     
    thirty-six, Sep 12, 2011
    #8
  9. Adam Funk

    Simon Mason Guest

    I get so few punctures these days, I never patch a tube but bin it and
    use a new tube every time.
     
    Simon Mason, Sep 12, 2011
    #9
  10. Adam Funk

    thirty-six Guest

    Please don't quote Jobst Brandt on this, he has managed to find the
    most convoluted way of patching tubes wrong. The cement you apply to
    the tube must be dry before applying the patch and the patch should be
    burnished. There are no rubber solvents left over if the cement is
    dry as every patch kit manufacturer intends. These chemical cure
    patches are safe to use immediately but the full cold cure is not
    thought complete for 24hrs which is why it is important not to inflate
    the tube unless within a tyre during that time. I think it is prudent
    not to install a freshly repaired tube, when the tube is undersize.
     
    thirty-six, Sep 12, 2011
    #10
  11. Adam Funk

    Rob Morley Guest

    That doesn't really add much to a discussion about patching tubes, does
    it?
     
    Rob Morley, Sep 12, 2011
    #11
  12. Adam Funk

    Mike Causer Guest

    But perhaps if those of us prepared to patch tubes were to send Simon an
    address label and some stamps he'd put the old tube into the box the
    new tube came out of and send the old one to us? Recycling is good, the
    gummint say.



    Mike
     
    Mike Causer, Sep 12, 2011
    #12
  13. Adam Funk

    Mike Causer Guest

    I like to put the newly-patched tube into a tyre and inflate it right
    way. That way the repair is checked, there's confirmation of no other
    holes, and if another tube has been taken out then it's known to be good.
    A patched tube that hasn't been tested is a liability.



    Mike
     
    Mike Causer, Sep 12, 2011
    #13
  14. In uk.rec.cycling.moderated on Mon, 12 Sep 2011 18:14:40 +0100
    I use a new tube on the rear, but getting suitable ones for the 24"
    front has proven tricky, so I put the spare tube in and patch the
    holed one when I get home.

    I haven't had a puncture for some time, but I do recall the day I got
    two on one ride home.

    Zebee
     
    Zebee Johnstone, Sep 12, 2011
    #14
  15. Adam Funk

    David Guest

    I haven't had a puncture for some time, but I do recall the day I got
    On my old commute of 23 miles round trip all on rough tow paths I never had
    a puncture but I'd go out in the evening and was almost guaranteed to get
    one. My 'best' was 7 in one ride!!

    D
     
    David, Sep 13, 2011
    #15
  16. In uk.rec.cycling.moderated on Tue, 13 Sep 2011 11:14:08 +0100
    My worst was 3 in under 10 mins.

    After #3 I decided this was God telling me not to go to work today, so
    I turned for home and rang in sick.

    No punctures on the way home....

    Zebee
     
    Zebee Johnstone, Sep 13, 2011
    #16
  17. Adam Funk

    Adam Funk Guest

    I agree with that last sentence in particular. The reason I don't
    normally test patches in a tyre (although I admit that it's a better
    practice) is that I normally put a new or previously patched spare
    tube in to save time in the short term, and patch the swapped-out tube
    later.
     
    Adam Funk, Sep 13, 2011
    #17
  18. Adam Funk

    Rob Morley Guest

    What an excellent idea. :) Probably better to pack a few together,
    though, to reduce the number of trips the postie makes and thus the
    carbon footprint.
     
    Rob Morley, Sep 19, 2011
    #18
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