New Reg Barber tamper base:

https://www.instagram.com/p/BFhdZZqE-ff/

(yes, worth the click through)

Now, how about THAT for a tamper? Double blind, anyone?

Hope you don't polish. (or is it Polish?)

nurxhunter wrote:There are believers who do not believe data.

Data free observations are occasionally entertaining, but in general more data is more good! Hope to see more especially if it can overturn the current trend of information that pressure isn't as important as superstition indicated.

JimF wrote:Since I ham-handed my experimental control, I did a third shot with the same grind, beans, dose, etc., but with a better execution of my usual tamp, measured to 30 lbs +/- .5 lb

Result: 30.7 g extracted. Taste: rich, buttery, chocolatey, with balanced sweet-bittersweet flavors.

So the 83g extraction of experiment 1 was not due to the grind, and the tamp wasn't so loose in that experiment that there would be air gaps, either.

I don't doubt the findings reported in the pdf, but I don't think the conclusion is correct because I can't reproduce their results on my equipment. Perhaps a highly consistent grind, a high precision basket, pre-infusion, carefully controlled temperature, and maybe other factors all combine to make the tamp insignificant in a commercial setup.

Interesting...Sounds like your setup is *slightly* inconsistent? I have never seen such a huge variation due to tamping alone. To compare/attempt to reproduce the test in the PDF, you have to settle the basket/portafilter by tapping on the counter, and then tamp straight down (that's what they did). If you have to nutate, NSWE etc, it seems like it is compensating for other aspects. In my experience, nutation etc do affect the flow. If you tamp straight-down-no-fuss, tamp pressure doesn't matter much. What's your 'usual' tamp technique btw?

Imho tamping is more of a way to cram all 14 or more grams of very fluffy ground coffee into a filter basket as not to loose half of it when locking in the PF.

Not saying tamping doesn't serve other purpose(s) but that IMO is the biggest reason as filter baskets would need to be notably larger without tamping and that would likely mean different extraction dynamics (larger volume of water etc) .

After that goal was met the 'tinker and tweak' minds of the (male) baristas turned it into something else...at least that is what I suspect

Well I can make a binary input, its only relevant to my setup of course, Izzo Pompeii with an HG-One. Tamping pressure, within reason, makes no difference. No tamp, doesnt work! Horrific, gushing spritzing pour that I would be unable to replicate other than massive under dosing or very coarse grind.

My tamper is a 'click' type and I have it set pretty light, I blind tasted a range of pressures and couldnt taste any difference, it was only the absense of any tamping that caused a complete fail!

I have always suspected the pressure was pretty irrelevant, consistency seems desirable to me as thats what I am striving for in my prep across the board, consistent dose, grind, level in the PF, consistent tamp, cue another god shot!

My experience, the experience of many others, and the physics of the situation, all seem to agree that fussing over the nth degree of precision tamp force is a wasted worry.

An analogy I like to use is, that tamping is like the light tapping a carpenter does when he starts a nail into the wood. This stands the nail up straight and square so that it has a better chance of going in straight without bending when he starts to hit it with real force. Tamping does the same thing to the puck... It starts the puck out level and straight so that when it's hit with the real force, there's less chance of a channel. Not zero chance though... As someone here once said, "spritz happens", It just improves your odds.

What a specific tamping force does not do, (becsuse the physics don't allow for it), is directly correlate either the flow rate or the quality of the shot, except again that starting as level and homogeneous as possible gives a better chance of an even extraction. Pre-infusion and slower pressure ramps purport to do the same kind of thing... To better prepare the puck before the hard pressure hits it.

-Peter

I (carefully) replicated JimF's results this morning. Baskets were prepped with Nossa Familia Full Cycle espresso blend, ground on a dosered Robur, and divided into 15.0g doses.

No tamp and 30# tamp.

The 30# tamp (using a flat Espro tamper) produced a lovely 28.6g extraction in 30s on my Spaz S1V1. No tamp produced a gusher/spritzer, which I tossed. Light tamping (weight of tamper) was almost as bad.

Typical extraction with 30# tamp.

Different equipment may produce different results. The Spaz S1 has a rotary pump, no preinfusion, and a 53mm basket. But these results are in line with my experience: tamp pressure matters, up to a point. I don't see much difference in "hard" tamping pressure (20#, 30#, 40#, etc.), but no tamping and very light tamping increase the likelihood of channeling.

Fortunately, tamping is relatively easy to get right. Keep it level, keep it consistent, and you should be fine.

RapidCoffee wrote:Different equipment may produce different results. The Spaz S1 has a rotary pump, no preinfusion, and a 53mm basket. But these results are in line with my experience: tamp pressure matters, up to a point. I don't see much difference in "hard" tamping pressure (20#, 30#, 40#, etc.), but no tamping and very light tamping increase the likelihood of channeling. Fortunately, tamping is relatively easy to get right. Keep it level, keep it consistent, and you should be fine.

Thanks for great information!

I was listening to the Sprudge Podcast this morning and they mentioned an article they did on the Puq Press:

The Puq Press, spotted on the bar at the UNIC booth at the 2016 Specialty Coffee Association of America Expo, delivers an automated and adjustable tamp. The user can input a specific weight of pressure... In a very loose demonstration, we were given shots of espresso at 15, 25, 27, and 30lbs of pressure with noticeable differences.

Frankly, these claims surprise me, but as a previous poster pointed out it could depend on the equipment used.

They have no data at PuqPress. I sure can see how this might be great for a commercial environment because it seems efficient and consistent.