There are a number of ways to join various types of brass, bronze or copper materials. The most popular method, especially with artistic work, is to “silver solder” (technically – silver brazing) the alloys together. It’s generally recommended you use a brazing product with at least 15% silver as this will allow you to join almost any copper or brass alloy to another. Some will use a silver brazing alloy with up to 56% silver content. But with that much silver, the brazing rod will be very expensive. Most people use an oxy-acetylene torch for brazing.
For a secondary choice, many artists use TIG welding, although this requires more skill than brazing. A silicon bronze filler material is often used. Some prefer to Stick weld which is a good choice for particularly thicker sections over 1/8″. For Stick welding, a silicon bronze or aluminum bronze electrode is a popular choice. If color match is critical, then finding the right filler material can be very difficult and time consuming. For lighter color bronzes, use an aluminum bronze, and for more of a reddish bronze, use a silicon bronze filler metal.
Any time you are working with copper or brass products that are thick or large, preheat is often used since copper has such a high thermal conductivity.