Backflushing
Backflushing is an important cleaning process for any espresso machine, however it is often NOT recommended by manufacturers. This is due to the risk of damage to the machine if it's done incorrectly, therefore if you choose to undertake this procedure you do so at your own risk. That said, it is performed by many professional and amateur baristas and can be done safely so long as a few important guidelines are followed.
I would recommend reading Randy Glass' Backflushing Guide in conjunction with this page as it is more detailed, and links are at the bottom of the page to a couple of other resources; this page is intended to show the basics of how it's performed on the Quaha / Imat machines and the technique I personally use.
Disclaimer:
Note: Your machine MUST be fitted with a 3-way valve to perform this operation without damaging your machine! The series 1 machines do not have the 3-way valve. A 3-way valve releases pressure from the portafilter when the brewing cycle is stopped and allows this to drain into the drip tray. Backflushing involves pumping water into a filter basket with no holes, so the pressure can quickly build beyond what the machine was designed for if care is not taken.
Perform this at your own risk. The operation listed below has been performed with no complications other than those described, and has yielded satisfactory results, however basic mechanical skills are required to do this. It should be simply a matter of following the instructions, but since manufacturers can change their specifications over time and since I can make no guarantee as to the skills of the person performing it, I can take no responsibility if your machine is damaged during the operation.
Description
Whenever you brew a shot of espresso, invariably some coffee grounds and the associated oils will be left on the showerscreen, or even below the showerscreen. Over time these oils get deposited all through the grouphead, leading to unpleasant flavours in your coffee. Backflushing is the process which removes these oils and returns your machine to a clean state.
Method
Tools required:
- Espresso machine cleaning detergent (available from many coffee supplies retailers)
- Blind filter basket (a filter basket with no holes. Otherwise packing tape to cover the holes as shown if you don't have a blind filter basket)
Remove the showerscreen and screw and sit them in the bottom of the drip tray.
The base of the group head after removing the showerscreen. Plenty of dirty old coffee grounds here!
The showerscreen (r) and custom-made diffuser disc (l), both coated with stale oils.
Turn the machine on for a few minutes. The detergent in the filter basket ready to go.
Load the portafilter onto the grouphead and run the pump very briefly, about 0.5 seconds max, and then stop. Repeat this process until you see some white foam exiting the 3-way valve exit into the drip tray and then leave for 5 minutes.
Some of the froth exiting the 3-way valve outlet
...and bringing with it plenty of muck and grunge
No it's not some failed latté art - that's what was left behind after the group was cleaned!
Repeat the process with new detergent a few times until the suds are all clean and white with no oils.
The base of the group after the clean - still looks brown but that's just tarnish of the brass. Importantly, it's clear of any old oils.
Now repeat the process with the portafilter only just locked in and jiggle from side to side so the areas around the portafilter are cleaned, e.g. the gasket. A little should overflow around the portafilter during this process.
Finally, clean the blind filter basket thoroughly and repeat the above processes with just water to clean everything of the detergent.
The showerscreen and diffuser disc after sitting in the drip tray for a few minutes with the detergent
The finished product!
Finally, brew a shot of espresso with some old beans and discard the brew just to make sure there's no detergent left in the system.
More information:
