I'd be worried about messing up the puck but maybe it's fine. It would have to be a pretty good size pot for dunking, a lot more water than is really necessary.

I spent a lot of time fooling around with measuring the effects of various preheating schemes. The easiest method I came up with was using a non-metal piston and heating the portafilter with a flame (our gas stove). I just needed water for the shot. The temperature would be at around 92°C and maybe drop 1°C after 35 seconds. If I preheated the basket I could push it up a few degrees.

I still want a plastic piston but something about putting the PF on a direct flame made me nervous.

Jonk wrote:Wait, kind of "pre-infusing" both the top and bottom of the puck? please report back with results, if that's what you meant!

I tried this morning just putting basket into the pot of water (about 2-3cm water) without water on top of the basket for about 15 seconds, then poured water over and pulled my shot. These last couple weeks I've learned to pull "blooming" style shots, where I go to 4-5 bar until drip (usually about 10 seconds), pull back to <1 bar, wait as long as my patience holds out usually another 10-30s, then pull and try to hit between 5 and 9, which takes less than 20 more seconds for a 1:3 ratio. That final pull is generally a little spongy, but I think I like the resulting drink.

With the basket bottom-preheat, the basket was hot to touch, the shot began dripping almost right away when I pulled to 4-5 bar, and the pull was super spongy from the start. Overall it tasted comparable to the other shot, but realize, these days most espresso tastes the same to me with major differences only being processing or origin.

Here's where it gets maybe interesting for you all. In my pantry, there's just enough 50-day old light roast for 3 shots that doesn't really do it for me anymore and was headed for the compost. I wanted to do four tests but at the moment the other coffees I have are tasty and I did not want to sacrifice them.

All three tests prep was same: paper on bottom, very fine ground coffee, umikot, tamp, paper and screen on top pressed down carefully but firmly by fingers. Obviously no shots were pulled, I was just curious what impact these preheats had. Didn't measure any basket temps but they were very hot to the touch.

1. basket into boiled water, covered 1 minute
2. water on top and basket into boiled water, covered 1 minute
3. water on top only, 15 seconds

#2 resulted in a floating puck, I wonder if there's a precise moment when everything is JUST saturated we could pull a shot.

Whatever cracks you see are just me trying to handle the semi-dry puck.

Lance Hendricks mentions in his Robot review video that he preheats both the portafilter and the basket on top of his kettle. This sounds very practical to me, as you don't need to mess with hot water or drying the basket, while simultaneously boiling the water for the shot.

That's how I used to preheat, sitting the PF and basket on top of the lid of a small saucepan with boiling water inside. It worked well but I agree with Jon that a double pour is easier. And by my measurements is equally effective.

I burned myself once or twice with boiling water doing extra pours. So I added a silicone cover for the portafilter handle. Even when I was heating the PF directly on the flame of the stove the silicone made it no problem to handle. Seems like an accessory that someone should be selling. Maybe someone does? OE perhaps?

That looks a lot nicer than my $1 silicone cover.

I like the magnets idea, very clever. I recently bought some more of those super strong neodymium mini magnets as I discovered that they are the ticket for keeping the arms up in the simplest, easiest to operate, and least obtrusive way. Maybe with the extras I'll see if I can fashion a wooden handle.

This morning, I attempted to do the double-pour method and I disturbed the coffee puck altogether, resulting in a messy shot. I wonder if I understood the process correctly. Here are the steps I followed:

- I prepared the espresso shot as usual: added ground coffee + shower screen + hot water
- I Drained the hot water, flowing to the walls of the PF.
- I refilled the basket with hot water and proceeded to extract the shot.

Is this the actual process, or did I get that wrong? thanks!

That is the way that some do it, when I do it I do not dump the water out, I heat enough boiling water to continue pouring into the basket and just let it overflow. Sometimes I will tilt slightly, but other times I just pour straight in. This works perfectly for me.

What I 'think' may be happening with your first attempt is that the screen lifted a bit, this can be prevented by pushing the silicone knob that extends past the screen into the puck so that the screen sits tight on the coffee. A few times I got a muddy mess from pouring water into the basket and it was because the water got under the screen and lifted it a bit.

Ken