Oh No !!! Another old chestnut rears its ugly head.
Kurt Sperry wondered "what empirical, quantifiable . . . ways silver brazing is better than brass brazing . . ." in reference to some recent posts on the subject.
Blah Blah Blah ! This is one of those MANY bike related topics that have virtually NO link to empiricism or measure or quantifiable reasoning. Nope. Nada. Zilch. Sort of related to the old "how many angels can dance on the head of a pin ?" unanswerable dopey question that once pestered theology for so long. Maybe the two topics originated with the same writer ?
When brazing a steel frame there are so many variables in regards to the skill and methods of the builder, what filler metal is used, what base metal alloy and heat treat, the length and temperature of the heating AND cooling cycles, drafts, etc. etc. that simple comparisons and generalizations that "one is better than another" just make very little sense. And all the variability ensures that there is virtually NO way to easily measure and or quantify differences except in a very general way. Which is why most framebuilders shrugged their collective shoulders and realized LONG ago that (once you get good at brazing) you can acheive good results with a number of different filler rods in a wide variety of ways with few failures that can be clearly linked to the filler rod alone. The filler metal is usually chosen more by what the builder is familiar with and prefers, and what works well for the particular joint and brazing operation chosen. Sub-optimal results usually only arise when a builder tries some new combo they are not familiar with, or their skills are not good enough to do the job properly in the first place.
And in the end after all the horseshit being flung around finally settles from this debate, after hearing this stuff for over two decades, the simple truth IMHO is that the better method depends on whichever method YOU WANT to believe AT THE TIME ! If you are riding a brass-brazed job then you can marvel at how "snappy" and "extra-stiff" the slightly higher temperatures have supposedly made your frame. Yep. If you are riding a silver-brazed frame then you can marvel in thinking that your frame has an extra bit of "liveliness" or "stiffness" or fatigue life or whatever due to the slightly lower temperatures that it was brazed at. Yep. Whatever the small differences might exist they pale in regards to so many other MAJOR differences in design, geometry, materials, and MOST IMPORTANTLY the skill of the builder, that as long as the bike doesn't fall to bits as you ride it, they in effect do not add up to the proverbial "hill of beans". Well-designed and built bikes exist in both forms, silver and brass. Why I've even heard a rumor that some modern bikes can even be welded up with STEEL filler rods ! But that can't possibly work ! <G>
The point is to RIDE the bike isn't it ? Don't get bogged down in the silly and the trivial (Which is better - side pull or center pull ?). Listen to the endless passionate opinions that rage back and forth and then laugh and shake your head and do the only thing that makes sense - Go for a bike ride !
Empiricism (and opinion) is great - thats why Red bikes are so much faster than Blue ones ! <G> Cheers, Mike Fabian (prefers blue bikes, actually) San Francisco