Clumping and Tamping

#1: Post by **cai42** » June 1st, 2008, 7:22 pm

Greetings,

Why doesn't tamping with the usual amount of pressure eliminate the clumping problem? It would seem to me that all that pressure should compress the ground coffee and eliminate the clumps.

Cliff Isackson

#2: Post by HB » June 1st, 2008, 7:39 pm

The pressure of tamping is small compared to the pressure of 9 bar, so the problem isn't "squishing" the space between clumps. The problem is that clumps have variable size and density, resulting in uneven distribution of coffee. In other words, if you sliced a puck formed from clumpy coffee into perfectly pie-shaped wedges, the wedges would not weigh the same.

#3: Post by **Randy G.** » June 1st, 2008, 7:54 pm

Dan said: "The pressure of tamping is small compared to the pressure of 9 bar..."
A 35 pound tamp with a 58mm tamper is only 8.75 pounds/sq. in. of pressure on the coffee.

...and why doesn't the last post in a thread have a "Quote" button.. Quite inconvenient.. or is it just at my end?

#4: Post by HB » June 2nd, 2008, 6:42 pm

Randy G. wrote:...and why doesn't the last post in a thread have a "Quote" button.. Quite inconvenient.. or is it just at my end?

Follow-on discussion split/merged to Last post does not have "quote" option.

#5: Post by **malachi** » June 3rd, 2008, 12:38 am

Tamping is purely intended to preserve your dream "perfect density" bed of coffee.
Using pressure to create this "perfect bed" from uneven distribution is somewhere between challenging (and requiring far more power than a human is likely to be able to exert) and simply impossible.

June 3rd, 2008, 1:06 pm

How would you characterize the importance of tamping? Does it do much useful beyond mashing the grounds below the shower screen if the initial distribution is good?

eric

#7: Post by **cannonfodder** » June 4th, 2008, 10:07 pm

Tamping is important, but less critical than distribution and dose in my opinion. A good tamp is the icing on the cake. It will not make a bad distribution or dose any better but a bad tamp can destroy a good dose and distribution. It simply helps to ensure an even density devoid of, well, voids. Light tamp, heavy tamp, does not matter just as long as it is consistent.

June 7th, 2008, 1:34 pm

Greetings,
Do baristas in a competition mix the ground beans with needles, pins, and other pointed objects? If not, why not?

Cliff Isackson

#9: Post by **Marshall** » June 7th, 2008, 1:39 pm

This isn't mentioned very often, but a firm tamp allows you to turn the portafilter over and shake off loose grounds around the collar, instead of bumping it with the tamper and unseating the puck.

#10: Post by **Marshall** » June 7th, 2008, 1:41 pm

cai42 wrote:Greetings,
Do baristas in a competition mix the ground beans with needles, pins, and other pointed objects? If not, why not?

Cliff Isackson

No. The judges would laugh themselves silly and forget to take notes.