> There are obviously marks a ways away from both the
upper and lower head tube lugs on the appropriate tubes. Must these
marks have come from flexing or bending, though?
> could these marks have been made by an improper brazing temperature and
what we are seeing is the limit of travel of too high a temperature?
Perhaps even something on the surface of the tube that overheated and
caused these marks?
Tom Sanders Lansing, Mi
I've only done a little metalworking but from my experiences the discoloration you refer to (as when metal is brazed or when, say, a tool is reheated for tempering) is a surface effect. It probably would have been removed when the frame was cleaned up for painting or repainting, or when the present owner removed the repaint.
If you'll look again at the photos Dale posted, not only are the tubes discolored at the arrows Dale added, but if you look closely you will see that there are also distortions in the light reflections indicating that the surface is not flat. This is most visible on the downtube in the very last photo... see how the otherwise smooth edge of the hotspot of reflected light dips in at the top and pops out at the bottom? Since those distortions in the light reflections line up perfectly with the other discolorations (indicated by the arrows), that's a good indication that they are ripples, not oxidation colors from heat.
Bob Hovey
Columbus, GA