Well I bought a new bathroom scale so I decided to use it to test how hard I've been tamping. Turns out I'm tamping WAY too hard! probably 2x too much! So I backed off the tamp and ground a little finer. At first I found I was getting a lot of spritzing like this. I found that tamping too slowly, trying to hit 30lbs on the nose caused this. I practiced getting the right force in a quicker motion and that seemed to solve the spritzing. Interesting how even after being at this for well over a year now I still find major holes in my technique! Ok, I always knew I was tamping a bit hard but never knew just how much.

You might try reading something written after 1990, since 30lb tamps have roughly the same status today as phlogiston. If your heavier tamping reduced channeling, your technical problem is with the way you distribute the grounds prior to tamping.

Tamping "too hard" isn't a bad thing.
It doesn't (per se) improve your coffee but it's not going to degrade the flavour either.

There are a LOT of more important things to worry about than the amount of pressure you use when tamping (especially assuming you're vaguely consistent with that pressure).

another_jim wrote:You might try reading something written after 1990

ha, sarcasm.

Most of the time an extreme tamp works with a coarser grind and higher dose. If you are having channeling problems try grinding a little finer and drop you dose a half gram, and watch your distribution. I use to use the 800 pound gorilla tamps as well. My kitchen counter would actually creak under the pressure. The tamp is down on the list of importance but a bad tamp will mess up a good distribution, but no amount of tamping will compensate for a bad distribution. The key is just to be consistent. Now a days I use a light tamp, 15-20 pounds I would guess and finer grind and lower dose.

another_jim wrote:You might try reading something written after 1990, since 30lb tamps have roughly the same status today as phlogiston. If your heavier tamping reduced channeling, your technical problem is with the way you distribute the grounds prior to tamping.

I love the phlogiston reference / analogy.

I agree although important tamping pressure is pretty far down the list. If you decide that you want to perfect everything to a T chris coffee sells a tamp mat that you can set to your desired pressure with your bath scale and you will know what your pressure is every time. With practice you will be able to discard the mat since your body will develop a memory for the correct pressure from the constant use of the mat.

Nixter mentioned trying to get the speed of his tamping motion dialed in to get better results. I have wondered if this plays a role as well. In the beginning of my journey I was very particular on position, level maintaining a square bottom surface to the coffee bed etc, and in doing this found that I was gradually tamping to around 30 lbs. Instead of a quick tamp motion like most do. What do you guys feel about this? Any ideas if speed of compression makes a difference?

The first time I ran into the 30 # standard was in Schoemer's book. The reason they chose 30 # was to tamp hard enough to achieve the results they wanted, but soft enough to avoid carpal tunnel for their baristas in a commercial setting. Somehow that 30 # got translated into an immutable standard. Relative to the other things one does to prep the coffee tamp pressure is relatively unimportant and the range of acceptable tamps have been theorized to be between 10 and 90 pounds depending on the writer/coffee/machine/temperature/humidity, etc.

hperry wrote:Somehow that 30 # got translated into an immutable standard.

Along with quite a few other parables and parameters. While they are all somewhat less than immutable, and depend on kit, technique, humidity, and quite possibly the phase of the moon (well, I haven't done any experimentation, have you!?!) the 'Golden Rule' parameters are a really good place to start. If you use these parameters (30 seconds-ish, 30 pounds, thirty ml per shot, 90°C to 96°C or 195°F to 205°F, fresh roasted beans ground straight into the PF) you're almost guaranteed to end up with something that works, regardless of bean, blend, or kit. Or humidity, day of the week, or phase of the moon.
Sure, there are a ton of outliers, and almost every technique could benefit from straying from that set of 'rules', but it's a great place to start a newbie on the path.

The only downside is that it starts, as you indicate, to be a religious dogma, and there are some that have seen a black cat in front of them just prior to a bad shot, and now are convinced that a black cat crossing their portafilter is bad and won't be persuaded otherwise. Apologies to Intelly and their blend.

It's what you do to learn the ropes, and just like any other gig, you have to learn to play within the structure before you start to experiment. Learning this way gets them 'centered', and they can start to learn what happens when each of those parameters is futzed with. Then they can start futzing all on their own.

The point I was making was slightly different. The original reason for the 30 # tamp was that for Schoemer it was a compromise between the 90 # in vogue then and a tamp that would work, but not cause carpal tunnel syndrome. In these forums there has been argument by competant users for anything from practically no tamp to much heavier than 30 #. Of all the "standards" this was one originally established as a practical balance between commercial and quality considerations. It is fine if someone wants to start there, but I find that the pressure and style of tamp needed varies substantially from machine to machine.

I have not noticed that before. I have several different machines, I use the same tamp with each. Each may require a different grind and/or dose with any particular coffee but I always use the same tamp. I am in the 'does not really matter' camp. If you tamp light or heavy is of little consequence, as long as you are consistent, and level. Now a days I tend to grind finer and tamp light, but that is just me.