Origin of the Polishing Twirl

by **cafeIKE** on Tue Nov 17, 2009 9:07 pm

Imagine my surprise :shock:

With a polished 57mm tamper, not cleaned after the previous shot and an ~8.5g dose.

A slight twist of the wrist stops the lift-off :oops:

by **JimWright** on Tue Nov 17, 2009 9:18 pm

LOL... was the tamper wet or something? I wonder why the grounds would adhere to the tamper surface strongly enough to stick notwithstanding the much greater surface area in the PF...

by **cafeIKE** on Tue Nov 17, 2009 10:03 pm

The tamper was definitely not wet. The relative humidity at the time was ~10%

by **JimWright** on Tue Nov 17, 2009 10:56 pm

Hmmmm. Was it your first shot of the day?

Wondering if some slightly damp grounds might have stuck to it harder than expected from the day before or something - otherwise, reaching for an explanation for this level of adhesion...

by **gyro** on Tue Nov 17, 2009 11:50 pm

Looks familiar...

by **mivanitsky** on Wed Nov 18, 2009 1:02 am

I did exactly the same thing day before yesterday. Grind was very fine, humidity was high, and I was building a single. I pulled the tamper straight out, a bit too quickly. My effort looked exactly like the two above. The shot was salvagable. I put it back in the PF, twirled and did a nutating tamp to reseat the puck, gave another tamp, and removed the tamper. Decent looking extraction, which tasted ok, not great.

I have never done this with a larger basket.

Mike

by **cafeIKE** on Wed Nov 18, 2009 1:07 am

JimWright wrote:Hmmmm. Was it your first shot of the day?

Wondering if some slightly damp grounds might have stuck to it harder than expected from the day before or something - otherwise, reaching for an explanation for this level of adhesion...

No, 2nd shot. I always clean up at the end of the day. If I don't the missus does.

I [always] wipe down the tamper after every shot and place it on a towel. :oops:

What's really interesting, I was able to replace the puck, apply a little pressure, twist to remove and the shot flowed beautifully.

by **JimWright** on Wed Nov 18, 2009 1:34 am

At high humidity, this seems more likely, but at 10%, surprising! In any event, even if it doesn't pull the puck out of the basket, the tamper only has to pull off a tiny bit of coffee to problematically disrupt the uniform puck surface - to the extent the twirl can dislodge any mildly adhesive grounds from the tamper and keep them in place with the rest of the coffee, the polish makes sense to me.

by **Psyd** on Wed Nov 18, 2009 8:04 pm

JimWright wrote:At high humidity, this seems more likely, but at 10%, surprising!

Nah, we have 10% and less around here all the time.
It's the static electricity that holds the puck to the tamp! ; >

by **Randy G.** on Wed Nov 18, 2009 9:33 pm

I had to check the calendar to make sure it wasn't 4/1.


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