E61 Espresso Machines - BackFlushing Instructions:
Back flushing can be done only to semi automatic espresso machines that include a manual or 3 way valve (like Rancilio Silvia or Expobar machines). Backflushing removes coffee oils residue from the grouphead and from parts coming in touch with actual coffee flow such as the valves and grouphead shower screen.
Cleaning frequently is important. The coffee residue built up in these fairly hot areas gets dry and can easily clog the coffee / water passages or make it hard to insert the portafilter handle into the grouphead.
Use 3/4 Urnex cafiza packet for excellent results.
First remove the shot basket from the portafilter and insert the blind filter basket. Pour 3/4 of Cafiza powder packet into the blind filter and close the portafilter tightly into the group head all the way . Hit the brew lever or the brew switch (like you were to brew coffee) for 5 to 10 seconds. Listen for the system to pressurize. You'll know it's pressurized because the noise will decrease. At this point, once the pump noise almost silent, push the lever all the way down. A pressurized stream of water with cleaning foam will shoot into the drip tray below. keep backflushing the system by repeating the process 5-10 times until the water runs clean to the tray and without dirt or Cafiza foam.
Once you rinsed clean the components, repeat the backflushing steps above but without detergent to wash any remains of the detergent. Then remove the blind basket, insert back the shot basket into the portafilter, wipe out your tray and make an espresso shot. Dispose the first two espresso cups, you're now ready to make espressos all over again.
To clean your portafilter, shot basket and drip tray, simply mix the remaining 1/4 of the detergent packet with warm water in a bowl and let them soak for about 10 minutes. There's no scrubbing necessary. The detergent will literally lift the crud right off the components. You can use proper espresso brush if necessary.
It is recommended to use a small Espresso Brush daily to clean inside the grouphead around the gasket to prevent built up since the grouphead is always hot and coffee residue can builtup quickly.