Nick wrote:When the grinder seems slow... make up for it by grinding earlier.

In which case the coffee will start to stale.


Keep in mind - the value of the practice of leaving the portafilter in the group and tamping into the basket will differ from one style of group to another.

Also - if you choose to "overheat" the portafilter with your hot water - keep in mind you'll need to completely dry the basket after doing so, which will eliminate much if not all of the theoretical value.

malachi wrote:Keep in mind - the value of the practice of leaving the portafilter in the group and tamping into the basket will differ from one style of group to another.

Why is that? Is it flush timing you are referring to?

malachi wrote:In which case the coffee will start to stale.

No it won't. I wasn't talking about grinding in advance... I was talking about starting the grinder earlier. The "clumping" that Danny mentions could be an issue for some I suppose. Depends on the grinder.

malachi wrote:Also - if you choose to "overheat" the portafilter with your hot water - keep in mind you'll need to completely dry the basket after doing so, which will eliminate much if not all of the theoretical value.

Why would that eliminate the theoretical value?

It's always fun discussing things with malachi. Too bad he's not real... just an imaginary manifestation of the id of the coffee industry.

Abe Carmeli wrote:Why is that? Is it flush timing you are referring to?

Saturated groups will cool differently from groups that use a thermosyphon which will cool differently from groups that don't use any method to stabilize group temp will cool differently from actively heated (grin) groups.

And some groups, of course, do not require a flush at all.

Nick wrote:Why would that eliminate the theoretical value?

You heat the portafilter up.
Then it cools off again as you dry it.

The honest truth...

I'm sure there are baristas out there for whom the small change in portafilter temp, even if skilled enough to build a shot in less than 30 seconds, is going to represent a limiting factor. For those people - there are so few areas for improvement that they have no choice but to focus on these types of techniques.

For the other 99.9999999999% of us, however, there are other limiting factors and issues that are far more worth focusing on as improvement in these other areas is going to have significant results in the cup.

malachi wrote:Saturated groups will cool differently from groups that use a thermosyphon which will cool differently from groups that don't use any method to stabilize group temp will cool differently from actively heated (grin) groups.

And some groups, of course, do not require a flush at all.

I don't see how that is related to the question at hand, re: the P/F cool down when detached from the group. It will cool down regardless of the technology used to heat the group. Am I missing something here?

You mentioned the group cooling as well. This is, of course, in reference to the group not the PF. And, as Barry notes, the group is what is important in this case.

i'm not sure the group cools significantly when the portafilter is removed... there's no doubt that heat radiates from the showerscreen, but that happens with or without the portafilter in place, so i guess for there to be significant cooldown the rate of heat loss through the showerscreen would have to increase with the portafilter removed. i'm not sure that happens.

I have seen the effects of locking a cool PF on my group temp and the effect is surprising but with my crummy technique, I know it didn't affect my shot at all


Sean

lennoncs wrote:I have seen the effects of locking a cool PF on my group temp and the effect is surprising

but, in that case, you've introduced a heat sink. i would expect a bit of a cooldown then, although at a slower rate than most folks expect (the conductive transfer points are fairly small).

malachi wrote:You heat the portafilter up.
Then it cools off again as you dry it.

It cools off if you don't heat it up too, and a dry-wipe takes 0.5 to 1.5 seconds. If you heat it up, it'll end up at a higher temperature when you're pulling the shot... no?

I'm still not clear on what effect taking the PF away from the group head has on the temp that the coffee sees.

So far I've seen two measurements for the portafilter, Andy's and Barry's posted earlier in this thread.

They do not show the same result, but both agree to-

1. 10-20 degree F heat loss over a minute.

2. 5-10 degree F heat loss over 30 seconds.

3. ? degree F heat loss in the first 5 seconds. (Andy says rapid temp drop, Barry's chart shows no change)

The three time frames roughly correspond to 1. A leisurely grind, dose and tamp into the portafilter. 2. Quite fast dose and tamp into the portafilter. 3. Taking out the pf only to drop in the filled basket.

According to Abe Carmeli and Barry (earlier in this thread) the group head would not cool down much. A little heat would be drawn from it when the now-cooler portafilter was re-attached, perhaps negligible?

I'm thinking the next step would be to measure (how?) the effect on the temperature of the brew water (or coffee puck) as the portafilter warms up again.

Sorry I don't have the tools or know-how to help with this, but I would love to see the results! Although at the same time I am thinking that most people have figured out how to compensate for this . . . the important thing being a constant routine.

Henry

hbuchtel wrote:I'm still not clear on what effect taking the PF away from the group head has on the temp that the coffee sees.

After the coffee emerges from the bottom of the basket... and before it hits your (hopefully preheated) cup.

Again, negligible with a crotchless/naked portafilter... but not with a "normal" spouted one.

hbuchtel wrote:3. ? degree F heat loss in the first 5 seconds. (Andy says rapid temp drop, Barry's chart shows no change)

actually, the chart shows immediate change. i just forgot to mention that the pf was pulled 10 seconds in (iirc). i usually let the datalogger run for at least a few seconds to establish the baseline condition. sorry for the omission.

hbuchtel wrote:I'm thinking the next step would be to measure (how?) the effect on the temperature of the brew water (or coffee puck) as the portafilter warms up again.

i have some data on the puck. i'll try to look up the details this evening. sorry, it's really the wrong time of year for me to be doing this.


--barry "roasting in a mall"

Barry, when you have time can you post some of the warming/cooling portafilter test results that you mentioned earlier in the thread?

Much appreciated,

Henry

barry wrote:i'm not sure the group cools significantly when the portafilter is removed... there's no doubt that heat radiates from the showerscreen, but that happens with or without the portafilter in place, so i guess for there to be significant cooldown the rate of heat loss through the showerscreen would have to increase with the portafilter removed. i'm not sure that happens.

Funny, I always kept thinking that heat transfer is proportional to ΔT. And that would make for a big difference for the group whether or not the PF is on or off (roughly some 40°C)...

recall that the portafilter radiates heat to the atmosphere, so with the portafilter installed the group heat loss is group + portafilter. removing the portafilter may or may not increase the heat loss (more direct radiation to atmosphere, but smaller total surface area radiating).