Peppersass wrote: After WDT, I use my mini-whisk to even the top layer of grounds, and while doing so leave a small depression or divot in the middle of the puck -- i.e., create a slightly concave surface. This has completely eliminated halo extractions. I'm using a flat tamper and have had some thoughts that going back to a convex tamper might have a similar effect.

I've also used a miniwhisk and then a Londinium tool, both for a long time. Now that I've tried thinner pins, I would not like to go back to the previous thicker versions.

Peppersass wrote:I use a BT Wedge distribution tool and no tamper when preparing doubles. It would be nice to see that techniques studied.

The same has been suggested on the Decent forum, so I plan to try this in a future testing round

Peppersass wrote:Finally, does anyone make/sell a Hog? I remember the tease on that but found an opportunity to try one out.

Yes, but I am not sure I am authorized to advertise this publicly on the forum, so if you're interested, I guess that you can contact me with a private message

PIXIllate wrote:Very interesting raw data set. Would be more interesting if a basic E61 profile was tried and then maybe a run with a medium roast.

As it stands it would appear that you can't over tap/agitate the grounds and an even puck is king.

I'll use an espresso roast from April for the next tests: if a classic E61 profile gives good results with these beans I'll stick to it for the tests

Stéphane wrote:... the low extraction pressure has also probably helped avoid part of the channeling of the worst shots.

Welcome to Home-Barista, Stéphane.

Jake_G wrote:Did anyone else notice the "slight" shift in protocol for the shots using the Hog?

The dose was dropped to 18g from 18.5g, but the grind was unchanged and the beverage weight was held constant.

I don't want to diminish the body of work that was done here, because it was clearly a huge amount of work to pull all of these shots and record everything. But I can't help but see the EY and earlier first drops as being rather suspect to the change in dose. Now, the higher peak pressure is rather curious...

[...]

**Edit**
I care because taking the 22.1% EY (the highest of the pack) and "correcting" for the change in dose (which doesn't really work because TDS changes, too but shows how sensitive the EY% is to dose) shifts the outcome by quite a lot.

22.1% * 18.0 (actual dose) / 18.5 (representative dose of the pack) = 21.5%

A good follow up, is Stéphane is willing, would be to cut the Hog shots short to maintain brew ratio. Equivalent yield would be 40g*18/18.5 = 38.9g.
Call it 39g to keep it simple.

I never would have thought that 1g output could really shift the flavor, and I don't imagine it will. But it will certainly impact the EY% in ways that make you go hmmmm...

Well spotted Jake! I have no idea why I forgot this! However I'm not sure that the actual impact is as high as your calculation suggests: extraction is not linear with the dose, so a 3% increase in dose won't result in a 3% increase in extraction yield.

This is visible on the below graphs (sliced espresso shots): my guess is that a 1g output difference could have changed the EY from 22.1% to 22.0 or 21.9%...



In the additional tests that John has mentioned earlier, I did not forget to change the target output when I modified the coffee dose! (but unfortunately, strangely, for the Hog shot, the automatic stop led to a higher output than expected!)





On top of this, here is the first shot with the Hog and same dose as the other tested methods: you can again see an earlier first drop and a much higher pressure peak. EY was 22.3% and it was the best shot of all. Shots without the Hog that led to similar pressure peaks (dialing in phase) were significantly less enjoyable.



The only objective of the dose reduction with the hog was to reach a similar range of pressure. I've never noticed a significant influence of the Hog on the height of the puck. For these tests, the clearance between the puck surface and the shower screen was about 4 mm.

Welcome, Stéphane!

Stéphane wrote:Yes, but I am not sure I am authorized to advertise this publicly on the forum, so if you're interested, I guess that you can contact me with a private message

I don't see any problem with posting a Hog tool link on this thread.

This is a great, and much need discussion. Thank you, John for starting it and Stèphane for participating.

I was very intrigued by the fact that numerous small taps also improved in the flavor profile and, iirc, the EY. Anyone who uses a Shot Collar is probably already doing multiple small taps to try to get all of the grounds below the spinning bar, I know I am, and I've found that once this is done, I haven't felt the need to use WDT stirring. This would probably still benefit from the hog, though, as far as I can see here in his thread. Curious to hear what others have to say about that.

Funny, I tried searching the forums for a thread on the Shot Collar, and the only one I found dates back to 2016. I'd think if they were that unpopular, they'd be off the market by now. I bought mine only about 2 months ago, and after playing with it briefly, it sat in its box, but I've been using it pretty consistently this past week...ever since the Kafatek catch cups were shipped out, and I've been impressed. It really does a great job distributing the grounds. While some refer to it's upper part as a dosing funnel, I find that amusing. It's pretty much straight sided and quite narrow, making it anything but a funnel, but I've figured out a pretty good workflow, setting my stainless canning funnel in top of it.

Some speculation to chew on:
1) Randomizing the grinds and distributing them evenly in the puck is the best way to ensure a good extraction.
2) Stirring the grinds (or shaking the crap out of them in a container) is the most effective way to achieve randomization.
3) Tapping does essentially nothing to randomize grinds or improve distribution. However, vertical taps collapse/compress the grinds, in a slightly different way than tamping. Like tamping, this may reduce channeling and thereby improve water flow through the puck.
4) The Hog tool is intriguing because it provides a mechanism for rapidly wetting ("pre"infusing) the puck. This should reduce the extraction gradient that normally occurs in the puck (upper layers extract more than lower layers), and could account for higher reported extraction yields.

RapidCoffee wrote: 4) The Hog tool is intriguing because it provides a mechanism for rapidly wetting ("pre"infusing) the puck. This should reduce the extraction gradient that normally occurs in the puck (upper layers extract more than lower layers), and could account for higher reported extraction yields.

This makes me wonder whether the Hog could be a substitute for long, slow pre-infusion, ala the Slayer. The drop in dose is counter-intuitive to that idea, but the shot did run faster, which is consistent with possibly being able to grind much finer.

Stéphane, please post your info on procuring a Hog!