Hello fellow home barista,

I need some help diagnosing a potential problem of using bottomless PF. I had recently tried bottomless PF and found that some of the portafilter holes did not pour out liquid (espresso). Im pretty sure the grind is fine enough for espresso (triple checked on that). It would be great if i have a photo of it but didnt get the chance to take one, i'll see if i can post it tomorrow.

Some of the parameters that i can share are as follow:
1. Brew temp : 92.5 C
2. Pressure : around 9
3. Pre Brew : 14-16s
4. Standard basket

I had a perfect blonding of espresso on the naked pf when the pressure was going over 10/11, but it was with different coffee beans. I did tweak on the brew pump pressure so it goes around 9 bar now.

I havent got the chance to tweak the machine to go over 10 bar again. Probably will try to when putting new batch of coffee beans; but for now do you have any inputs on this? Any comments are welcome.

Thanks a lot!

I would assume this is an issue of either channeling or uneven distribution in the puck. Essentially, water will always find the path of least resistance through your puck. So if parts of your puck are significantly (or insignificantly) more or less dense than other parts, water will not penetrate the denser parts. This will leave "dead spots" or dry spots in your bottomless PF, which is why they are so great for diagnosing user error. If the uneven distribution is TOO bad, the shot can be palatable.

Channeling is a little different but works on the same concept. If there spots in your puck with structural issues, water will create small burrows or fissures in the puck. Essentially the same effect, but more drastic. If channeling occurs, most shots will be very sour and unpalatable.

I don't know how increased or decreased pressure can effect channeling, although I imagine that higher pressures will accentuate the negative effects of poor distribution.

How does the espresso taste? If it tastes good then some dead spots shouldn't matter.

IF you're using VST or other straight edged baskets, this is a non-issue assuming it tastes fine. There's this whole science about the increased surface areas of these baskets that makes this more common. Ultimately, there is uneven distributions because it's impossible to achieve perfections. However, if the taste is bad then it might be too uneven...

JerDGold wrote:I would assume this is an issue of either channeling or uneven distribution in the puck. Essentially, water will always find the path of least resistance through your puck. So if parts of your puck are significantly (or insignificantly) more or less dense than other parts, water will not penetrate the denser parts. This will leave "dead spots" or dry spots in your bottomless PF, which is why they are so great for diagnosing user error. If the uneven distribution is TOO bad, the shot can be palatable

Thanks for the input JerD, i did try to dose and distribute evenly (i forgot to mention i use a funnel); and just as you mentioned the espresso is quite palatable (not that sour). I did notice that the shot still stay around the center though (not gushing etc etc)

estib wrote:How does the espresso taste? If it tastes good then some dead spots shouldn't matter.

It tastes good but i was under the impression that it can go better, maybe im that obsessed with the espresso porn shot :p

brianl wrote:IF you're using VST or other straight edged baskets, this is a non-issue assuming it tastes fine. There's this whole science about the increased surface areas of these baskets that makes this more common. Ultimately, there is uneven distributions because it's impossible to achieve perfections. However, if the taste is bad then it might be too uneven...

Hello brianl, i tried brewing one with standard PF basket, will try changing it to VST tomorrow. Again, it tastes fine but just as you said, maybe i was aiming for perfection.. thanks for pointing that out!!

I would venture to guess that a literal perfect distribution is physically impossible to achieve. As you get closer with better technique and higher end equipment, the law of diminishing returns takes effect. I experienced a similar frustration as you at one point, and learned eventually that while I should keep trying to perfect my technique, it is also important to top and enjoy what you have at the same time.

You can try different tamping/distribution techniques to improve your flow, but I assure you that if you do, your shots will get worse before they get better, because new techniques are...well...new.

If your stream is staying around the center, that's pretty good. If the stream is dancing all over the place and/or you're getting multiple streams dancing all over the place then you have more room for improvement.

Might sound odd from a person that has a thread open about perfecting bottomless pours, but I don't have any taste issues with mine, I just want the pours to look prettier... anyways onto the actual point. I'd say getting dose, yield, time, and temperature dialed in will get you 95% of the way, I'm not sure if minor channeling (If you just have a spurt or two, or maybe some dead space, Major channeling is more like wobbly off center cones with a dirty shirt) actually makes a HUGE taste difference.. I'm sure it makes a difference, but we might just be over analyzing it.