Just got my bottomless PF back with a LM triple basket over the weekend, and I got to try it for the first time yesterday. I got a spot spraying result of the channeling and 2 spots on my second try. I went back to the double basket on the third try, and it was fine, with the vertical stripping. Chris is right, the triple basket is a lot more challenging than the double basket, but it sure was fun to watch super creamy crema dripping off the PF...
We tried a bottomless PF at my favorite cafe starting last Friday and it certainly seems to make a difference, although we're not sure why. The cafe owner probably has a crook back now from watching the way the pour builds up.
Wow. What a fantastic idea for a modification. I took a drill bushing and a 2 inch hole saw to my La San Marco PF last night after reading parts of this thread and I am super happy. In terms of diagnosing shot problems during the pour, I feel like I have suddenly been granted sight. My shots taste better too (might just be because I am so revved up about how bad-ass the shots look coming out of the basket). I pulled some shots with some just-roasted, unrested, beans to observe the over-gassy nature of the shot. The pour looked like a volcano! Thanks guys for this idea. If you are going to do the mod at home be carefull with the brass as it is extremely soft. It is very easy to gouge the heck out the PF with the hole saw. Don't try it unless you put a bushing in the PF spout hole to fit the 1/4 inch bit of the hole saw. My PF is not as pretty as the pro-job, but it sure was cheap and fast. The La San Marco 85 isn't such a looker anyway so who cares!
Finally read this thread. You guys are nuts. But a good idea is a good idea. Tempted to try. Especially because of all the well-established c-geeks reporting results. As I was reading I was hoping to find more and more blind taste test results. Plenty here I guess, but would like to see more. I think a glass bottom portafilter would be cool. Or for that matter an all-glass portafilter (of course you could only use the knock box once). But some of the photos you guys are taking are great, and if the hype is legitimate this could be revolutionary. I mostly skimmed, but did not notice if anyone did side by side comparison of in-basket and in-cup temperature differences. Is it possible a slight temperature difference accounts for taste difference?
While you're at it with the hole saws, anyone ever try trepanning? It may leave you without future need for a coffee buzz altogether...
i talked with Dr. John at NASCORE. he indicated that (with the bottomless portafilter) you have a measurable increase in TDS (total disolved solids). this would explain the mouthfeel change. in addition, he indicated that a normal portafilter does, in fact, have back-pressure issues and the bottomless portafilter eliminates this.
We just got a crotchless pf last week (kindly organised by kaanage); agree 100% with the improved mouthfeel comment, Chris. Haven't had much of a chance to play around with it yet, but we did split the first few drops off from the rest of the espresso on one shot. Those first few drops were the thickest espresso that I've ever had! Makes me want to make a whole cup of them!
Anyhoo, we should be giving four or so more pfs the chop soon!
Chris,
Thanks for putting up all those pics on the webpage; it's a fantastic resource.
Andy,
Thanks a lot. Your really red pour looked so good that I just licked my screen.
i talked with Dr. John at NASCORE. he indicated that (with the bottomless portafilter) you have a measurable increase in TDS (total disolved solids). this would explain the mouthfeel change. in addition, he indicated that a normal portafilter does, in fact, have back-pressure issues and the bottomless portafilter eliminates this.
I've run a few tests, and they tentatively suggest a different explanation.
I alternated shots through regular and bottomless portafilters using the same double basket. I kept grind, dose (~18g), tamp, temp, etc as consistent as possible. I manually stopped each shot when the total volume (crema + liquid) reached 1.5 oz. The volume was measured with an uncalibrated Starbucks shotglass. For each shot I measured the elapsed time, net weight, and total dissolved solids (TDS).
Compared to the bottomless shots, it took 10-15% longer to get the same 1.5 oz shot volume with the regular portafilter. And the regular pf shots weighed 15-20% more.
It seems clear that the regular portafilter breaks down some of the crema as the espresso trickles through. This is like pouring your beer down the side of the glass instead of pouring it straight into the bottom of the glass. Everyone knows you get more beer in the glass by pouring it down the side.
Consequently, a bottomless portafilter shot (at the same volume as a regular pf shot) consists of more crema and less liquid. Of course it tastes richer and creamier -- it's more concentrated. This observation is backed up by the TDS numbers. They were 10-15% higher for the bottomless shots.
In addition, if the barista takes care to adjust her grind to maintain a fixed shot time -- say, 25-27 secs -- the grind for the bottomless shots will end up a wee bit finer. This will result in shots that are higher still in TDS.
These tentative conclusions are based on very limited testing, so I'd love to hear if others find similar results. Also, those folks with automatic machines can extract a fixed amount of liquid and measure the variation in volume. I wasn't able to do this with my semi-auto machine.
As far as the backpressure issue goes:
If this really is a problem, the tendency of people to stuff triple baskets in regular portafilters certainly makes it worse.
But I'm skeptical that it's really a problem. A quarter inch of water column pressure converts to 0.0006 bar. Hard to believe that tiny backpressure affects the environment inside the basket, except maybe for the last 0.001" of flow.
Of course you could always eliminate all backpressure by making deeper portafilters.
Not yet, so far I've just compared alternate shots with the same grind, dose and volume. Now that I've seen the greater crema retention of the bottomless shots, it's obvious that pulling equal volumes is not the way to go. The next step, when I get a round tuit, is to compare regular vs. bottomless shots prepared with the same grind and dose, cutting the pump at comparable weights.
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