A coffee blind filter is a tool used to clean the group head of an espresso machine. It is a metal filter with no holes, which allows water to flow through the group head without passing through the coffee basket. When inserted into the group head and combined with a cleaning solution, the blind filter flushes out any buildup or residue that may accumulate over time.

Regular use of a coffee blind filter is essential in maintaining the quality of espresso and prolonging the life of the espresso machine. It is an effective way to remove oils, milk residue, and other impurities that can affect the taste and performance of the machine.

Overall, using a coffee blind filter is an important part of espresso machine maintenance, and can ensure that your coffee is always at its best.