Soft soldering on gold

But still: What can be done or used to have prettier soft soldered
joint? 
  1. Use as little as possible. TIX brand soft solder is a bit
    harder/stronger than some of the others, and melts lower, so it may
    let you use less. Plus, it tends to stay brighter than some others.
    But it’s still a white soft solder.

  2. Do the job some other way. Laser welders and PUK welders, for
    example, can often directly weld things that one used to have to use
    soft solders for. Even if you don’t have the equipment, some pieces
    are worth jobbing out so someone who does have the equipment, in
    order to avoid the unfortunate use of soft solders. Other options may
    include cold joints, like rivets or screws, or the like. A few cases
    might even be appropriate for some glues, which aren’t much better
    than soft solders for strength, but at least, can sometimes be less
    visually obvious.

  3. And if you must use soft solder, it can often be gold plated
    (brush platers are good for such spot plating. Not always a great
    quality plate, but you usually only need a bit of coverage to mask
    the obvious color difference. There used to be, and may still, be a
    product specifically marketed to give a copper plate to soft solder
    just by brushing on. You might even get the same thing just with
    copper sulphate solution or well used (bluish color) pickle. Not
    sure about that, but try it. The copper color isn’t a match for
    yellow gold either, but is closer, and might be less obvious.

Hope that helps.
Peter Rowe