Ruby Fluid® soldering and tinning paste flux. 2 Oz (56.7g). Plumbers, workers in brass, copper, tin, steel and stained glass will achieve superior results with this easy to use product. Produce strong, neat and durable joints. Ruby Fluid® allows solder to flow in a thin film. Adheres quickly and stays where it is applied. Also available in liquid (Forney 38120). Carded version is Forney 60303.