Puly Caff powder Industry standard for group head cleaning. For back flushing espresso coffee machines, price shown is for a 900 Gram tub.
If the coffee machine in use has a three way solenoid then it theory can be back flushed. Near on all commercial machines use a three way solenoid.
Some domestic machines like the Gaggia Classic and the Rancilio Silvia also have three way solenoids.
Back flush with Puly Caff powder give three advantages:
Better tasting espresso.
Better Aroma no espresso.
Cleaner tannin free pipes resulting in better heat transference, consequently better Crema layer !