Unexpected results when forgetting to tamp

[darrensandford]

This morning, in my sleep-addled haze, I dosed my double basket, smoothed off the coffee as usual (N-S-E-W), then for some reason I locked it straight into the macine without tamping.

What was unexpected was the result, which was it choked the machine, the spout was dripping very slowly.

I dumped the lot, dosed the same and tamped hard. This gave me my usual 30-second pour.

I normally tamp quite hard, but this is making me wonder if I am missing something. Was it because the grounds, although loose, were pushed against the shower screen?

I am half-tempted to play with using the tamper very lightly to give some headroom, but no more. Given the choking I got this morning, I may need to go coarser on the grind.

Thoughts?

[kahvedelisi]

probably because the grounds were loose, they absorbed water easily and all swelled instantly, that may be the reason why your machine choked (ie. pourover coffee)

[mrgnomer]

Could be as you suspect you did what I think is called a showerscreen tamp that compressed the grinds a bit but left no headspace. What kind of machine do you have? Is it preinfusing? Is your roast pretty fresh?

I'd guess the blooming grinds without any headspace for expansion locked into the pf and offered enough water pressure resistance to choke your machine.

Interesting, though. The advice I've heard often enough for channeling problems was coarsen the grind and/or lighten the tamp which seems counter-intuitive. It wouldn't work if your technique is right on, I assume, but if it's your technique that's the cause of channeling fast pours not your grind size then indeed coarsening up or lightening your tamp would be the way to go. Bad technique with too fine of a grind or too hard of a tamp encourages channeling, I find.

I've often wondered if I'm really grinding too fine or tamping too hard and just getting controlled channeling extractions more than good, even ones. More than once I've choked a machine with same grind and same tamp and it led me to wonder if maybe at those times my technique was on and that's why the machine choked.

[darrensandford]

The machine is a cleaned-up used Rancilio Epoca, HX with a vibe pump and tank. It doesn't pre-infuse, but it does go a good 6-7 seconds from pump-on before you can hear the pump quieten from the pressure build-up and coffee start to appear on a normal extraction. The beans are about 4 days from roasting, and are no where near darkly roasted.

I hadn't considered that what I thought was a good pour was actually a choke with a bit of chanelling all adding up to a 25 second extraction. I think I need to try and replicate all this with my naked portafilter, but I think I will need a good few more beans first!

[Randy G.]

This morning, in my sleep-addled haze, I dosed my double basket, smoothed off the coffee as usual (N-S-E-W), then for some reason I locked it straight into the macine without tamping.

A few years ago, during an early, sleep-fogged prep, I was refilling Silvia's reservoir and nearly poured the water into Rocky's bean hopper!

[TrlstanC]

I've been meaning to make a post about a similiar tamp vs. no tamp surprise. I was curious about the effects of preinfusion, and after playing around a bit pulling shots ended up dosing, leveling and tamping, but instead of locking in, and pulling a shot, just pouring a couple onces of water in to the portafilter - just to get an idea of what was happening. I then dug around in the wet grounds with a toothpick to see how deep the water penetrated and if it soaked in evenly or not. I then did the same thing, but without tamping, just dosing and leveling.

The surprising result was that the water in the tamped shot soaked through noticeably further then the untamped, the opposite of what I was expecting. The tamped grinds were wet about 1/2 way through, maybe more, and the untamped grinds were always less then 1/2 way soaked through. I tried it out a couple times, keeping the dose and grind consistent, and got the same results.

A few theories on what was happening:

1. It was just a freak occurance.
2. The tamp 'locked in' some bad distribution and allowed water to seep down through little channels
3. The tamp 'locked in' the distribution of the fines in the puck, while the fines in the untamped pucked all got funneled down and clogged up any passages through the grinds.

After inspecting the grinds from my grinder (Gaggia MDF) I'm guessing that option 3 is most likely. After sifting a dose of ground coffee it was clear that there were a decent amount of fines. Now I'm wondering if this could be one of the advantages of conical grinders, if the way that they initially shear the beans down to grinding size may prevent the creation of a lot of fines, and that gives you a more consistent puck, and shot.

[darrensandford]

The surprising result was that the water in the tamped shot soaked through noticeably further then the untamped, the opposite of what I was expecting. The tamped grinds were wet about 1/2 way through, maybe more, and the untamped grinds were always less then 1/2 way soaked through. I tried it out a couple times, keeping the dose and grind consistent, and got the same results.

Thinking about it, untamped coffee probably has a lot of air between the particles, meaning that there is less contact between the grains of coffee. I think that this would give the pre-infusion unpressurised water a harder time, as the water would have to overcome surface tension to pass from one particle to another across an air gap, but would soak easily between touching particle, meaning that the water would soak through a tamped puck more quickly.

...maybe.

[darrensandford]

A few years ago, during an early, sleep-fogged prep, I was refilling Silvia's reservoir and nearly poured the water into Rocky's bean hopper!

Eep! Not the way to start the day!

[mrgnomer]

The machine is a cleaned-up used Rancilio Epoca, HX with a vibe pump and tank. It doesn't pre-infuse, but it does go a good 6-7 seconds from pump-on before you can hear the pump quieten from the pressure build-up and coffee start to appear on a normal extraction. The beans are about 4 days from roasting, and are no where near darkly roasted.

I hadn't considered that what I thought was a good pour was actually a choke with a bit of chanelling all adding up to a 25 second extraction. I think I need to try and replicate all this with my naked portafilter, but I think I will need a good few more beans first!

Diagnosing extraction and playing with variables I find hooked me on espresso and makes it really fun.

I don't know the design of the Epoca but I wouldn't be surprised if it has a solenoid to control preinfusion. 6-7 sec is about what I get with what I believe is the lever actuated preinfusion of the Vetrano I've got.

As far as too fine and controlled 25 sec choke I've wondered about that when looking at my pucks after extraction. Even stopped before any naked pf squirting or significant blonding I find signs of channeling, mostly holes near the center of the puck. When I don't see holes is when a once in a blue moon shot chokes with no flow or the extraction tends to a deep charactered ristretto where it once was an average tasting normale.

Could be a it's a God Shot factor where God Shot is just variables that need to be tweaked more precisely come together every once in a while by chance. Something to have fun with for sure.

[The_Mighty_Bean]

A few years ago, during an early, sleep-fogged prep, I was refilling Silvia's reservoir and nearly poured the water into Rocky's bean hopper!

I was cleaning the grouphead with a wet toothbrush, and then sleepily poked the same dirty, wet thing up the clean, dry spout of my grinder. Swearing and scrubbing ensued.

[mrgnomer]

Hey, that's some good responses. More stuff to consider.

Surface tension of un tamped vs. tamped grinds relative to a preinfusing wetting. Fines migrating down to clog the basket in an untamped dose. Or just accident.

The factor of fines in the grind was discussed in quite a few topics, I think, with relation to grind quality. I'd forgotten about that. Quality/type of grind/grinder would make a difference if fines are a significant variable relative to an un-tamped or a very lightly tamped puck.

[cannonfodder]

A similar discussion from a couple of years ago Purpose of the Tamp. A search on tamping will bring back pages of information. As I understand, our obsession over tamping is unique to America. Most of Europe does not tamp, or they use the grinder attached tamping thingamajig. I have had good shots using both techniques, you just have to adjust your grind the method you use. Your dose is also very important, a half gram off either way will make a noticeable difference in the shot timing. I would suspect that some machines work better than others using the no-tamp method. The slower infusing E61 type groups may work better than the fast infusing solenoid controlled groups. On my Elektra, headspace is very critical and a no tamp shot is usually a meltdown with coffee spraying everywhere.

I once forgot to put the cup under the portafilter while stumbling around in a sleep deprived state.

[Bertie Doe]

A similar discussion from a couple of years ago Purpose of the Tamp. A search on tamping will bring back pages of information. As I understand, our obsession over tamping is unique to America. Most of Europe does not tamp, or they use the grinder attached tamping thingamajig. I have had good shots using both techniques, you just have to adjust your grind the method you use.

Carlo Odello, an influential figure in Italian barista standards and co-author of the book l'Espresso Italiano Tasting. When talking about the L'Espresso Italiano Certifico, mention was made of the absence of tamping in these guidelines, his responce was :-

Regarding tamping, I can quote the book "Espresso Italiano Specialist", which is an official book from the International Institute of Coffee Taster and of the Italian Espresso National Institute. It is suggested that its force should be not less than 5 kgs. Regarding tamping in Italy, I agree you usually see a very quick, and sometimes light, tamping. Beside the technical parameters, I think a good barista has mainly to evaluate its espresso from a sensory point of view. You can use more or less force in tamping: the most important think is that you get a valid espresso. I refer in particular to the profile indicated by the Italian Espresso National Institute (which you can find here)

[KillerQ]

A few years ago, during an early, sleep-fogged prep, I was refilling Silvia's reservoir and nearly poured the water into Rocky's bean hopper!

Haha -- absolutely classic!

[CafSuperCharged]

probably because the grounds were loose, they absorbed water easily and all swelled instantly, that may be the reason why your machine choked (ie. pourover coffee)

Personally, I find this a very likely hypothesis, but expect grind evenness will play a big role. A grinder that produces relatively much dust as side-effect may cause a different effect.

As I understand, our obsession over tamping is unique to America.

You turned it into an add-on business.

Most of Europe does not tamp, or they use the grinder attached tamping thingamajig.

True. Especially outside Italy (which is most of Europe) this is nuanced. Either they use espresso machines to emulate the national/regional coffee style (e.g. drip filter coffee in the Netherlands), or their own version of what they think is espresso. If a region's customers expect to sit down with a cup of coffee, bartenders may feel the price of a cup of coffee may be too high for a single shot espresso, or they may feel espresso is too strong for national tastes, so in both cases you are likely to end up with either a bad lungo or a small cup of drip filter like coffee at the same price as a larger cup of coffee in that style.
Generally there is a lack of training and tradition and it may well be the grinder is adjusted by the coffee vendor or espresso machine mechanic on an accidental visit. Usually there is no tamping involved here.
But then you may stumble upon an espresso bar that has a high espresso standard and diligently tamps time and again.
On several trips around Italy my experience is they generally (80%) do not tamp at all, not even on the compression disc attached to the grinder. This is based on experiences throughout Italy (North, Tuscany, Roma, Napoli and Sicily) and alike in villages or cities, in restaurants or highway gas station espresso bars, poorer or posher areas (however the coffee taste when changes when going South).
The internet and WBC may cause coffee-cultural changes that e.g. Italy might import from e.g. the U.S. I was a little surprised to see an Italian barista (said to be in the Italian top 5) in a restaurant in Amsterdam distribute and tamp seriously. But, my prejudice/expectation may have to significantly change in a year's time.
I would expect most of the home baristas in Europe to tamp however. At least I do. With flat Reg Barber, concave Espresso Vivace (Schomer) or a spring loaded flat Italian one.

Regards
Peter
Netherlands
Europe

[RapidCoffee]

This morning, in my sleep-addled haze, I dosed my double basket, smoothed off the coffee as usual (N-S-E-W), then for some reason I locked it straight into the macine without tamping.

What was unexpected was the result, which was it choked the machine, the spout was dripping very slowly.

I dumped the lot, dosed the same and tamped hard. This gave me my usual 30-second pour.

...

Thoughts?

Unexpected indeed. Being something of a skeptic, I decided to try this myself. I dosed two ridgeless double baskets at 17g, leveled both, tamped one and left the other untamped.
I then pulled a 30 second shot with each basket on my Vetrano. The untamped basket poured significantly faster, and yielded 46g of espresso for a brew ratio of 37%. The flavor was characteristic of a lungo shot: not bad, but slightly sour. The tamped basket poured as usual on my setup, resulting in 35g of espresso for a brew ratio of 48%. The flavor was typical of my normale doubles: rich, creamy, and much more to my liking.

I have no idea what happened in your situation, but these results make much more sense. An untamped puck should allow the water to percolate through the coffee bed faster, not slower. You can certainly get a decent pour with a light tamp (or no tamp), but in general you'll have to grind a bit finer to compensate.

[CafSuperCharged]

[...] I dosed two ridgeless double baskets at 17g, leveled both, tamped one and left the other untamped.[...]
pulled a 30 second shot with each basket [...]
untamped basket [...] 46g of espresso for a brew ratio of 37% [...]
flavor [...] not bad, but slightly sour [...]

tamped basket [...] 35g of espresso for a brew ratio of 48% [...]
flavor [...] rich, creamy, and much more to my liking.
[...]
I have no idea what happened in your situation, but these results make much more sense.[...]

Very interesting, John.

Now, would you be able to do an additional experiment and find the point where untamped pours the same grams of espresso, and brew ratio gets near your normale value?
Then, what grinder do you use and could you indicate the difference in grinder setting between these two versions?
Finally, how would you qualify the difference in taste?

Regards
Peter
Netherlands
Europe

[RapidCoffee]

Now, would you be able to do an additional experiment and find the point where untamped pours the same grams of espresso, and brew ratio gets near your normale value?

Maybe this summer, when things quiet down at work. But please feel free to carry on without me.

I make no claims that my little test is definitive. (For example, the untamped shot might have channeled, leading to the higher flow. There was no visual evidence of this in the naked pour, but it's a possibility.) Still, some claims require a higher level of substantiation than others. If you measured the specific gravity of water as 1.0, I'd accept that without hesitation. If you measured it as 2.0, red flags would go up all over the place, and I'd look for alternative explanations (malfunctioning equipment, operator error, etc.). In this case, the claim that untamped pucks offer more resistance to flow than tamped pucks seems rather unlikely to me. So with just one report and no independent verification, I'm not particularly inclined to spend much more time and energy on further testing.

Then, what grinder do you use and could you indicate the difference in grinder setting between these two versions?

Mazzer Super Jolly with brand new Duranium burr set. Beans were PT's Bella Vita espresso blend. No change in grinder setting; I prepped both pucks and then pulled the shots, stopping to weigh and taste each one. The only difference between the pours was tamping.

Finally, how would you qualify the difference in taste?

I don't have much to add to my observations above. Keep in mind that I'm not an expert taster, I did this test hours ago, and I didn't take notes. The untamped pour seemed slightly more sour and noticeably less rich than the tamped pour. The tamped pour had a creamier texture and better mouthfeel. I attribute this to the pour volume, not the tamp per se. The 37% brew ratio puts the untamped pour near the borderline between a lungo and a regular espresso, and that's where I'd put the taste profile.

[darrensandford]

I only tried it once (and not intentionally!), because my priority was getting a good cup at that time in the morning! I was just surprised at the result. I can't remember now how many days old the coffee was, but I have a feeling that it was a little young (1-2 days).

I imagine that if I tried more times, I would see a -lot- of variation in pour times, as before tamping I imagine the coffee has random voids and clumps, making it very hard to predict exactly what is going to happen. The whole point of the tamp is to remove voids and give an even puck, removing these uncertainties

Anyway, it's just another odd thing to make me go "Oh!" and not worry too much about.

[CafSuperCharged]

Maybe this summer, when things quiet down at work. But please feel free to carry on without me.

Thanks John.
Understand/appreciate the message. Reason I asked is your photos suggested you might have more serious kit and hence capable of an experiment with less variability in unwanted places.

I make no claims that my little test is definitive. (For example, the untamped shot might have channeled, leading to the higher flow. There was no visual evidence of this in the naked pour, but it's a possibility.) Still, some claims require a higher level of substantiation than others. If you measured the specific gravity of water as 1.0, I'd accept that without hesitation. If you measured it as 2.0, red flags would go up all over the place, and I'd look for alternative explanations (malfunctioning equipment, operator error, etc.). In this case, the claim that untamped pucks offer more resistance to flow than tamped pucks seems rather unlikely to me. So with just one report and no independent verification, I'm not particularly inclined to spend much more time and energy on further testing.

Well, you have been in this forum long enough and contributed so much I would respect your opinion anyhow. Other than that, university professor, in a conversation on "validity" the other day I was searching for the proper English translation of a Dutch word I would paraphrase in English as "repeat precision", but I digress.

I don't have much to add to my observations above. Keep in mind that I'm not an expert taster, I did this test hours ago, and I didn't take notes. The untamped pour seemed slightly more sour and noticeably less rich than the tamped pour. The tamped pour had a creamier texture and better mouthfeel. I attribute this to the pour volume, not the tamp per se. The 37% brew ratio puts the untamped pour near the borderline between a lungo and a regular espresso, and that's where I'd put the taste profile.

Objection! Contradictio in terminis. You start saying "Keep in mind that I'm not an expert taster", and then explain in fact you are.

The relevance of the experiment I proposed was the entire Italian market where caffè is a cheap commodity, yet around almost every corner and can be bought for a small amount. The French have their baguette (bread), the Italians caffè at low prices and national protests are imminent when prices would rise too fast. No tamping, in most outlets. And good to very good quality in most cases, especially when you are the nth in line (n > 1, 2 or 3 depending on the machine and its operator). This, I suppose, explains why it is hard to find espresso machines in Italian shops.
So there is much to be explored in the difference between that approach and the reference approach that sort of hovers over this forum.

Regards
Peter
Netherlands
Europe