Diagnosing channeling using a bottomless portafilter

This video shows how to use a bottomless portafilter to diagnose channelling. This is when water doesn’t evenly flow the the puck but exits through fractures in the puck causing channels. This causes over extraction from some parts and under extraction from others. The initial flow is acceptable. At about 23 seconds you can see a small jet lasting for 1 second indicating that the puck preparation could be improved. A jet lasting for longer would indicate significant issues with puck preparation. The flow is relatively fast as I aim for 1:2.5-3 ratio in 25-35 seconds. Overall the flow from the portafilter is just about acceptable. #espresso #coffee #coffeeaddict #coffeelatte #channeling #barista #baristaskill #homecoffee #lelitbianca #flowcontrol #coffeelover #baristaskills

[@dinsy512]

That looks like the channeling I get with my Flair 58: the coffee will not come through the middle of the coffee, only around the edges. I’m back with my Silvia whilst I figure out my next steps.

[@UnderstandingCoffee]

Interesting! For light and medium roasts, especially at lower pressures, the extraction may not look pretty. I’ve learnt that there generally little correlation between how the flow looks and taste!

[@mryoyo7741]

Thanks. What does mean shot coming from one spot and other spot dropping while other spot flow continues in the basket?

[@UnderstandingCoffee]

If this happens in the first few seconds, that’s ok. If it continues, then it indicates channeling. Note that a pretty looking shot doesn’t guarantee great flavours. Also extractions from light roasts and turbo shots don’t always look good.

[@mryoyo7741]

@@UnderstandingCoffee 🙏

[@JakubTarnawski]

Apart from that small jet, many of the holes seem to be untouched by water even by the end

[@UnderstandingCoffee]

Thanks for your comment. The coffee not coming out of some holes doesn’t necessarily indicate channeling. Medium and light roasts have thinner body so just don’t have the viscosity. The coffee flows just collect into streams on the basket due to surface tension.
You get better looking flow with coffees with better body , generally darker roasts, as they are thick and foamy which covers everything up.

[@alainreyers]

For me you need to grind finder….. the flow (imo) goes too quick

[@UnderstandingCoffee]

Thanks for your comment. I think opening up the flow and going for longer ratios prevents channeling and gives more predictable results (at the cost of lesser body which for me isn’t a compromise). A tighter grind might result in better looking flow but not necessarily a better tasting brew.

[@alainreyers]

@@UnderstandingCoffee just FYI since I use a puck screen I have no channeling anymore

[@UnderstandingCoffee]

@@alainreyersyes, a puck screen does help. I’ve used one in this video