I work primarily in Brass, Bronze and Copper, making jewelry and sculpture. The best alloy for my work is Low Fuming Bronze Brazing Rod. Your local welding probably has some you can try, but it must be the Low Fuming type. Try some bare rod not the flux coated. This alloy is low in copper, so tarnishes very slow (about 1/4 the rate of sterling silver). I order in large quantity from one of the manufactures like Aufhauser, who sells in minimum 50 lbs per diam. It is a bit more expensive than the others recommended here but worth it, especially for wearable items and small casting. Use a Boric Acid base flux not a Borax base. I buy the Roach Powder stuff at the Dollar Stores and mix it with water in a tall Olive jar till pancake batter consistency and dip the rod in it for a light flux coating when gas welding.