Dark roasted oily sticky coffee beans AND channeling?

Beginner and pro baristas share tips and tricks for making espresso.
fdoenz

#1: Post by fdoenz »

I have the feeling that dark roasted oily and sticky beans are more prone to channeling than lightly roasted beans?
Anybody the same suspicion, feeling or experience?
I am in the espresso hobby for now five years and I got a maniac in preparing my puck:
I start using the blind shaker, pour the grind into the portafilter with circular movements, then use the WDT, again circular movements, then level it and tamp it...yes nearly five minutes in all but the channels are exceptionally rare, but still more common with the above mentionned grains!
I use 20g for a shot of 30ml, I have less channels with this relatively heavy load, I am quite sure about this one!
Why oily beans? Well I love napolitan style espressos with a fair amount of robusta!
MANY THANKS ALREADY FOR YOUR INPUT!