Re: [CR]brazing...brass...silver...solder

Example: Racing:Jacques Boyer

Date: Wed, 12 Mar 2003 13:59:51 EST
Subject: Re: [CR]brazing...brass...silver...solder

Quick partial answer, Dale.. The term "silver soldering" is not a correct or accurate one but it's usage is widespread and is known to mean the brazing process (As contrasted to welding) with a brazing filler alloy that has a high percentage of silver. (the s=actual silver content can vary widely from around 20% to high 50s%) Silver brazing or soldering is versus brass brazing, in which it's filler material presumably has no silver content, but is brass rod or wire.

The heat ranges vary considerably too and lower percentage silver brazing material has a pretty high range, negating that benefit but aiding in flow/capillary action. The bit about brass frames breaking because of over heating versus silver holding up is not supported by the empirical evidence. The exception might be in the case in butted frames of really thin steel in the middle of the tubes where the gauges are thinnest. A well made frame by an experienced craftsperson does just fine in either mode. Most of the classic bikes we talk about here on the CR list are brass brazed together, be it fancy lugs or plain, and if correctly made and used, they keep on ticking for 100 years!

To further complicate the terminology is the phrase "Bronze welding" which is what many of us call filet brazing, i.e., building up artful puddles of liquid brass in a joint where no full lug is used...

Clear as mud?

Dale Brown
Greensboro, North Carolina