Needle spray and worm holes

[Buschy Senior Member Find all posts View Profile Close Buschy]

Does anyone know what could be causing the fine spray towards the middle > end of an extraction, and the partial worm hole in the puck shown below? Ive never had it before. It doesnt happen all the time. Pours are pretty good otherwise. Thanks.  

Beginning


Middle


Towards end


Note: this puck belongs to a different pour (taken a couple of shots before), but result is always the same. Hole ends up on the perimeter but at different locations - 1 oclock, 5 oclock, etc.).

[blanyon Senior Member Find all posts View Profile Close blanyon]

Re: Needle spray and worm holes

Two possibilities I can think of off the top of my head, dosing technique needs improving or your tamping is slightly off. I wouldnt worry about it too much if you are still happy with the coffee imho.

[espressed_is_best Member Find all posts View Profile Close espressed_is_best]

Re: Needle spray and worm holes

Looks like uneven dosing/tamping technique to me. Im no expert but I had a similar problem when I first got my pullman and naked group handle and once I sorted these two things out, no more tunneling in the puck and no spray while extracting   Hope this helps.

[espressed_is_best Member Find all posts View Profile Close espressed_is_best]

Re: Needle spray and worm holes

I should add tho that the extraction does look pretty damn tasty!

[gregpullman Senior Member Find all posts View Profile Close gregpullman]

Re: Needle spray and worm holes

Pin sprays can be caused by uneven tamping but looking at the puck theres a specific point where the channelling is coming from rather than one whole side being light-on. That indicates a single point which had insufficient coffee, which suggests a distribution problem. Clumping of the coffee grounds can cause this.

Doserless grinders are more prone to clumping than dosered ones because with a doser you can dose the coffee out as it comes off the burrs before it has time to stick to other bits of ground coffee. Some coffees / climates are more prone to causing clumping than others. So if thats part of the problem try to break up any clumps before tamping - http://www.home-barista.com/weiss-distribution-technique-steps.html describes the Weiss Distribution technique which can assist in breaking up clumps. A dosered grinder would be a quicker way of achieving the same result but you may have other reasons for preferring doserless.

Either way, once youve got the coffee all powdery and clump-free, give the pf a couple of gentle taps on your dosing forks to settle out any other voids, refill to the top of the basket, sweep off making sure you fill the edges, then tamp. Id be surprised if you dont see some improvement.

Greg

[Thundergod Sleep is overrated Find all posts View Profile Close Thundergod]

Re: Needle spray and worm holes

The worm hole is a classic example of channeling.
What you see is one end of the channel.
The fine spray is coming from the other end of the channel.

The usual culprit is uneven distribution and tamping.

Ive never had it before.

Youve developed the yips.

[Buschy Senior Member Find all posts View Profile Close Buschy]

Re: Needle spray and worm holes

I think youve nailed it. I suspected it was clumping but wanted to see what others came up with based on the photos. The problem started around the same time I went from doser to doserless grinder. Its also very humid in TSV right now and there are some fairly substantial clumps entering the filter basket. I thought I was removing them before tamping but I guess not consistently. Will try what you have suggested and see if it eliminates the problem. Cheers.

Pin sprays can be caused by uneven tamping but looking at the puck theres a specific point where the channelling is coming from rather than one whole side being light-on. That indicates a single point which had insufficient coffee, which suggests a distribution problem. Clumping of the coffee grounds can cause this.


Greg

[Shilling Member Find all posts View Profile Close Shilling]

Re: Needle spray and worm holes

theres always a possibility of scraping the surface when locking in the group handle. easiest to find out is lock it in as you normally would and then take it out.

i have seen a lot of cases where people will be very precise with dosing/distribution/tamping only to be careless when lcoking it in the group head.

luke