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Channelling and spray/spritz

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I’ve recently gone over to using my Aergrind until the Niche arrives, and it started off brilliantly with Mystery 8. The pour on my Sage DTP and bottomless PF was even and looked pretty good. The shots also tasted very nice!


I moved onto the ‘free’ pack from coffeelink, and it was just spraying/spritzing all over the place. I couldn’t get one clean pour. I use exactly the same prep with both beans.


I then moved onto some redber beans I had vac sealed in the freezer for a month or so. Same problem, spraying every where. Because of this I’m struggling to dial in, because it’s all over the place..


My prep is grind with Aergrind, tip into PF with funnel, stir a lot with mini whisk (with ends cut off), tap gently on rubber mat to level off, tamp loosely ensuring its level, then tamp again with more pressure, but not seriously hard.


I dose 17g which doesn’t touch the shower screen- I’ve checked that. PF and machine is pre heated. I have the motta tamper which I believe is a pretty good fit.


Sorry for the essay, but I’m getting quite frustrated!



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Some beans are difficult to get a good pour from, especially lighter roasted/tougher beans.


Sometimes you just need a better grinder. However there are other things to try:


Try down dosing to 16g and grinding finer.

Try up dosing to 18g and grinding coarser.

Try a new bag of beans.


Test your headspace with a penny. Place it on a tamped dry puck and then lock in and remove the PF, the penny should have just been ever so slightly pressed into the puck, this is about the right headspace.

Both too much and too little headspace can cause havoc with the pour.

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I did the penny test as you say, and there was no mark on the puck. So all good there I guess. To declump I’ve gone to another level and grind into a cup, shake it about and stir, pour into pf with funnel, then stir again. Still no luck, if anything, it’s gotten worse!


I did notice these beans are harder to grind on the Aergrind, so maybe I should have up and go back to the mystery 8 I have in the freezer..


Unless updosing and grinding coarser will make much difference?

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The penny should make a very slight mark on the puck. If there is too much headroom it can cause trouble.


The lighter roasted/harder to grind beans are also typically less volumous, so they compress more when tamped - so to achieve the same headroom you actually need to up dose.


I should note that having extra headroom is not necessarily a cause for concern, but it is definitely something to look into.


FWIW I am currently using some small (the beans are tiny), lightly roasted beans and I just cannot get a decent tasting drink out of them. I think they would be better brewed!

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  • 11 months later...

About channeling, something that I was said :

a too thin grit or too much pressed puck is prone to channeling, because the puck is too much resisting to the pressure, the water look for any defect to pass.

light roasts are known to be difficult . may be blendinc can  help at times .

A low pressure at the start opens the puck, and it flows more easily then (too fast, for me generally)

too large gap : lot of water motion

Hope that helps

Edited by Olek
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