Inconsistent flow rate (slow then very fast) & channeling

#1: Post by **NickWillWright** » March 10th, 2023, 6:30 am

I've been trying some new beans recently and I'm getting a very inconsistent flow rate. Shot starts off looking decent but then goes fast and watery looking at about the 10s - 15s mark. I can

My recipe is 17g in, 34g out (1:2) and at present that's about a 22s shot. I usually get this yield at about 27s for beans that I know and use often (and feel confident in). For sure I think the culprit is channeling as you'll see in the video. But I'm not sure what I'm doing wrong in the prep that's causing it? The beans also look dry to me as they are retail store bought and not freshly roasted, but they are a reputable coffee house in South Africa.

Beans:

Dose pre tamp:

Dose post tamp:

Extraction:

Any tips would be appreciated!

#2: Post by **erik82** » March 10th, 2023, 6:53 am

That's what happens with stale beans. Fresh beans are your solution. They're dried out and lack any form of resistance causing this. Crappy gear with pressurized filter baskets can mask this by trading in for a loss in taste. You can try grinding finer and see what happens but that's not a very good solution as the basics are lacking here.

#3: Post by **boren** » March 10th, 2023, 8:26 am

Short answer: Ditch those beans and get freshly roasted ones instead.

Long answer: Before you do, it might be interesting to try to compensate for this by increasing the dose until it just clears the shower-screen when you attach the portafilter (a couple of millimeters of headspace). This way, when the puck expands during extraction it would start pressing against the shower-screen, increasing pressure and reducing flow. You won't get good espresso out of it, but at least it should look closer to a proper shot

#4: Post by **Milligan** » March 10th, 2023, 9:43 am

I'd try going a bit finer first before throwing them in the garbage. I agree stale beans are hard to control. You can get them to extract usually with a bit of diligence. I've dug into stale Lavazza plenty of times in a pinch. Yours are still providing a little crema so they aren't as stale as my terrible Lavazza stash that looks like a dark brown laser coming out of the portafiler...

#5: Post by **zefkir** » March 10th, 2023, 1:04 pm

How does it taste? This is the only thing that matters.

#6: Post by **Nunas** » March 10th, 2023, 2:32 pm

Been there, done that. It's one of the reasons I got into home roasting...always fresh beans. Rather than bin store-bought the beans, which might not be totally stale, given the amount of crema, I'd first do both, up dose a bit and grind slightly finer.