How to Backflush and Clean your Espresso Machine
There are many factors that work together to pull a terrific shot of espresso. When shooting for that we often focus on things like getting the right bean, having the perfect grind, dosing the right amount, tamping evenly at the right pressure and the list goes on. Here in Clive’s Tech Department we believe the most forgotten factor in the realization of a delicious cup is the cleanliness of the machine used and how that lends to even extraction and clear taste. Too often when tuning up a machine we look in the group head, roll up our sleeves and prepare to go to battle with the scourge that is 2 or more years of built up coffee grounds, clogging up the inside of a group head and polluting the taste of the rest of our controlled process that is brewing espresso. We’re here to teach you how to spend five minutes with your machine to clean out your group head and improve your home espresso.
The place we want to start is with water and detergent backflushing. We recommend a water backflush on any day the machine is used, but if you can just manage once a week that will be fine as well. Detergent backflushing we recommend about once every other week on all machines except the machines that use E61 group heads, in the case of the E61 group head we recommend once every one or two months.
- Insert blind filter and add up to 1/2 teaspoon (3 g) of Full Circle wash or espresso cleaning tablets (only use Full Circle for detergent backflush). Lock your portafilter into the group head.
- Activate brew cycle for 10 seconds and allow the machine to release pressure. Repeat 5-8 times, depending on how dirty your group head is.
- Remove portafilter. Activate brew cycle and rinse portafilter in a stream of water from the grouphead. Stop cycle.
- Insert blind filter. Lock your portafilter into group head again, this time with a clean blind filter without the cleaner. Repeat step 2 to rinse and make sure no detergent residue is left.
- Make and discard a shot of espresso (only for detergent backflush).
- Soak filters and the metal portion of portafilter (do not submerge plastic handle) for 30 minutes in 1 teaspoon (6 g) of Full Circle powder per 32 oz. (1 L) of hot water.
- Rinse with water and put filters back (only for detergent backflush).
Once you incorporate backflushing into a monthly maintenance routine, the 5 extra minutes it takes to show your machine some love will save both your taste buds and your wallet but even a backflushing routine can’t clean out everything on the other side of your dispersion screen. However, a little scrubbing or a new dispersion screen can make a world of difference in the cup produced by your machine. The process of removing your dispersion screen and cleaning your machine is a simple one that we recommend once a week as a part of maintaining your machine and creating a quality cup of espresso. Below we will explore the removal of the different kinds of screens, cleaning and reinstalling.
Remove the screen
Central hex screw: Machines hold their dispersion screen in place in different ways. Some espresso machines like the A53 and Vivaldi have a hex screw in the center of the screen, holding it in place. With those machines, you can loosen the nut with the correct size wrench, 7mm in the case of La Spaziale machines, and once it is loosened it will unthread the rest of the way by hand, removing the screen with it.
Central flat head: Other machines like the La Marzoccos and Slayers have a flat head screw that holds their screens in place and requires the use of a short flat head to begin unthreading the screen. Once it has been loosened you can also unthread it the rest of the way by hand and the screen will come out with the screw.
Gasket tension: All machines using the E61 group have their screen held in a little differently though. Rather than use a screw to hold everything in place, E61s use the tension of the group gasket to lock the screen in place. To remove an E61 screen you’ll need a flathead screwdriver to pry out the screen and gasket, using the edge of the group head as counter torque to loosen it from where it is held.
Scrub the screen
Once you’ve removed your screen you can scrub all the built-up grime out of the inside of your group head and screen. To get all the unwanted build up out of your group we recommend a warm, wet rag and a Pallo brush. The rag will help to loosen up any hardened coffee grounds and debris inside the group head and screen. After you’ve scrubbed the screen and group with a rag give them a good scrubbing with a brush and use the rag again to clean out the leftovers.
We definitely recommend watching out to not use a brush with hard bristles on the screen as it can cause inconsistencies in how it disperses the water and give you channeling every time you pull shots with that screen in place.
Some machines have an internal dispersion plate that is removable as well as an external dispersion screen, these plates are removable and also will need to be cleaned as they can have coffee grind build up over time.
After somewhere between one and two years we recommend a new screen entirely for your machine as even with concise cleaning they wear and need replacing. The one exception to this is the dual screens on the La Spaziale A53 and Vivaldi; so long as they are correctly cleaned with a soft brush and not bent when reinserting to the group they are known to evenly disperse water for years.
Once the inside of your group and screen are pristine you can reinsert the screen the same way you removed it. When reinstalling a dispersion screen for a machine with a screw that holds it in place we recommend tightening it as tight as you can with your hand and testing the flow from the group head to make sure it is even. Generally, these screws do not have to be tightened past hand tight and doing so can cause the screen to warp, making them permanently damaged. However, if you notice inconsistent flow from the group after only tightening the nut hand tight go ahead and tighten it a half turn at a time and then retest the flow through the screen until it is even. For E61 groups we recommend using a food safe lubricant, such as Molykote 111, on the gasket to reseat the gasket and screen.
Now that you’ve cleaned your group head rejoice at the clear, concise flavor you’ve helped your machine to produce! Cheers!