Hi Don,

The link below is to a site with joint designs and weld procedures using the mig, tig, manual, and brazing processes for joining copper and copper alloys that might be helpful.

http://www.brazing.com/techguide/procedures/copper_welding.asp

From what I've read in Volume 4 of The Welding Handbook, Materials and Their Weldability, bronze isn't mentioned except in the following: "Copper alloys in which zinc is the major alloying element are generally called brasses. However, some alloys are known by other names, such as commercial bronze, Muntz metal, manganese bronze, and low fuming bronze. For joining considerations, brasses may be divided into three groups: Low zinc brasses with a maximum zinc content of 20%, high zinc brasses containing more than 20% zinc, and leaded brasses." Since you specified bronze with 90% copper and 10% zinc, would this fall into the low zinc brass category or bronze? I did a search and couldn't find any material specifications with the 90/10 composition under bronze or brass. I checked Jefferson's Welding Encyclopedia, and it states the following: "Bronze is a large group of copper, zinc, and tin alloys". "In general, these constituents are distributed in the following range: 70-90% copper, 1-25% zinc, and 1-18% tin". It also states that "brass is a generic name for alloys consisting essentially of copper and zinc". Please understand, I'm not trying to dispute you, I'm just trying to learn something new.