Swells in stripes...Channeling?

#1: Post by **TimEggers** » March 22nd, 2007, 1:29 pm

Hello friends,

I have noticed that at times I get swells in my stripes during an extraction. To better describe it the stripes sort of dance or swell in spots. The stripe will be even and then swell briefly then return to a more normal even stripe.

Is this a sign of channeling? I don't get gushers or shooters, but looking at the stripe it appears the flow is uneven in the sense the stripes swell and bulge as if getting moments of accelerated flow before the returning to a more stable flow.

If my descriptions aren't good I'll try to get a video of them, but my camera isn't that good...

#2: Post by **appa** » March 22nd, 2007, 1:32 pm

How do your pucks look afterwards?

March 22nd, 2007, 1:45 pm

#4: Post by DC » March 22nd, 2007, 2:07 pm

You mean one of those stripes suddenly swelling and then going back to normal?

I'd guess it meant faster flow, see it often at the end of shots. Never noticed a taste difference when I do see it though

#5: Post by **cannonfodder** » March 22nd, 2007, 2:11 pm

I believe I have a video showing what you describe in the Dialing in a new espresso machine, a step by step guide. I don't remember which video (I am at work and gvideo is throttled way down) but you may want to give them a quick view and see if you notice the same behavior.

To answer the question, yes, it is channeling. When you have a meltdown you get the jets spraying you in the eye. When you have more minor channeling you will get a bulge from the basket but no squirting. It will also present itself as a sudden large circular blob that appears on the cone and then subsides back to the striping.

March 22nd, 2007, 2:13 pm

My fears confirmed. Thank you. I have much work to do. Luckily I don't see it in every shot. Maybe 25% of them though...

#7: Post by **appa** » March 22nd, 2007, 2:51 pm

Hi Tim

I dont see signs of really bad chanelling (holes in the puck, etc),
maybe its just slight..

Can you taste the difference when this happens?

#8: Post by **cannonfodder** » March 22nd, 2007, 5:49 pm

Around second 25 there is sudden light spot that appears in the front of the cone and then goes away. Is that what you are referring to?

«missing video»

#9: Post by HB » March 22nd, 2007, 8:58 pm

TimEggers wrote:I have noticed that at times I get swells in my stripes during an extraction. To better describe it the stripes sort of dance or swell in spots. The stripe will be even and then swell briefly then return to a more normal even stripe.

Fresh coffee that's degassing can do that early to mid-extraction, or blends with high-crema producing coffees like Robusta. Otherwise I'm with Dave, sounds like (minor) pinholing.

March 23rd, 2007, 12:44 am

cannonfodder wrote:Around second 25 there is sudden light spot that appears in the front of the cone and then goes away. Is that what you are referring to?

«missing video»

Yeah! That's exactly it but mine are usually more subtle and I do see them mostly in the early part of the extraction. And yes the coffee is super fresh (3 days old). The shots do taste great though (but then again I'm still learning thanks to you guys).

I have some more work to do...(but man this is so much fun). I love this place!