Issues working with brass

About brass and what it does for metal art

In metal art one of the coolest metals to work with is brass. It has a golden color and is stronger than copper yet melts or softens at a somewhat lower temperature. The golden color does darken with time but this easily remedied with copper/brass polishes. Brass is a copper/zinc alloy that has other metals added to contribute specific properties to the alloy depending on its end use. There are over 400 brass alloys in use. The most common brass available is 260 cartridge brass. This is called this since it is used for casings on ammunition. It is the cheapest brass and has a brilliant yellow color when clean and polished.

Challenges in Torch Braze/Welding of Brass

One problem I encountered early on in my artist endeavors was trying to brazing brass to steel or to brass for that matter with ordinary bronze brazing rod. Problem with this is your common brass has a melting point approximately the same as your brazing rod. That is somewhere in the 1700 to 1800 fahrenheit neighborhood. Another peculiarity about heating brass is that it does not "flow" or liquify like bronze, silver or iron for that matter. At bright red heat it oxidizes extensively and gets a coating of black,green, and brown oxides. Whats more, is that if you are not diligent when heating the brass, after the oxidizing begins the metal will either collapse into a puddle or shrivel into a hideous form simular to what aluminum does. Another dilema is that you may inadvertly burn a hole in the brass if it is a relatively thin plate or sheet metal.

Types of brazing alloys for brass

One solution would be to use ample supply of flux to dissolve away oxides as they form. But a better and simpler solution is to use a brazing or soldering alloy at lower temperatures. Ideally, one would use one of the quality silver bearing brazing alloys yet these are prohibitively expensive for most artists.

An inespensive alternative is copper/phosphorus brazing alloys. These melt at about 1300 fahrenheit and the joints are stronger than the parent metals. There is one caveat of coarse. That is you cannot use them with ferrous alloys. The reason being the phosphorous from the brazing alloy will form extremely brittle phosphides with the iron possibly causing joint failure. One way to get around this is to braze "copper coupons" to the steel and use the copper/phosphorus rods to braze the copper to the brass. This mainly applies to joining brass sheet to steel sheet or rod or vise/versa where the copper joining is hidden. If you wish to join brass rod to a steel rod where the joint will be clearly visible from all angles then soldering with lead/tin solder might be the best bet. More on this later.