Soft soldering of copper tubes with copper, red coppercast and brass fittings for cold and hot water installation, heating installation 110°C (230°F). Lead-free, harmless to health and environment. No additional flux consumption, paste contains flux already. Thus less danger of corrosion. No overheating of tube and fitting because the melting of solder and the required temperature for soldering is clearly visible through the change of colour of paste. High filling level of soldering joint, thereby good stability. Easy cleaning of remnants which are soluable in cold water. Plastic bottle with brush integrated in cap which cannot get lost.