Over the years with in-house experimenting and working with over 20,000 clients, we arrived to a count of 50 extractions as an average to perform a backflush routine with detergent on a backflush-capable espresso machine. More frequent backflushing without detergent can happen more often, but the frequency needs to be considered as a higher frequency can have a detrimental impact on the internal parts, especially a vibration pump, of an espresso machine.
Again, the count of 50 is an average. Similar to descaling frequency, this count depends upon other, but different driving factors:
- Oiliness of the beans: the more oily the beans, the more rancid oils will accumulate behind and around the dispersion screen. Hence, more frequent backflushing is desired.
- Grind fineness: finer grinds, especially powder resulting from an inconsistent grind, will accumulate behind the the dispersion screen. Hence, more frequent backflushing is desired.
- Amount and type of detergent used: some detergents clean better than others: too much detergent can clog the grouphead and/or strip out the lubrication on the cams in the e61 lever grouphead (other groups may not be affected). Hence, if less or weaker detergent is used, more frequent backflushing is desired.
- If you leave the puck to dry in the portafilter in the grouphead: if you leave the puck in the portafilter in the grouphead, the rancid oils will accumulate with faster and greater intensity and will require a more frequent backflushing routine.
- Technique (short vs long): Typically, a long backflush routine is desired for machines with a rotary vane pump and a short backflush routine is desired for machines with vibration pump(s).