# Over extraction problem



## Milesy (Mar 8, 2012)

I have been experimenting with grinding finer and tamping less but I have got to the point where I think I am over extracting.

18g grounds into 36g liquids in 35 seconds.

I want to stick with the 18g and 36g as fixed variables as I like the dose and volume I enjoy.

At the moment I am maybe tamping with 10lbs of pressure and I am getting extraction quite far into the pour now with blonding not happening, however I might be going to far in the wrong direction. The result had a burnt looking crema before stirring. The taste was pretty bland in the mouth with not much happening. I have lost the fruity sourness (good sourness that is).

Should I back of on the grind or the tamp?


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## garydyke1 (Mar 9, 2011)

Keep the tamp as a fixed variable ....Back off the grind until your desired output is 32 seconds and taste & see if is what youre looking for, if try 28 seconds , and so on


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## Milesy (Mar 8, 2012)

Got it down to about 30 seconds and getting more fruityness now. The beans are quite gassy still which is complicating it though.


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## MikeHag (Mar 13, 2011)

Temperature too high perhaps?


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## tribs (Feb 21, 2012)

I see you have adjusted your pressure and I'm guessing you have a fairly new Classic. I have a suspicion that the new models have been designed to run hot and the higher stock pressure in some way cools them down quicker. Since I adjusted my pressure I tend to over extract and have to compensate by doing a much larger flush prior to pulling a shot to bring the temp right down. The upside is recovery is quicker, the downside being it harder to temp surf and using much more water. As such I am going down the route of DIY PID.


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## fatboyslim (Sep 29, 2011)

I have a PID and lately at 101 degrees, which equates to 92 degrees brew temp, I've noticed a lot of steam coming from the group head whilst purging. I'm wondering if the offset value is wrong.

I think if you are getting a PID you need a way to calibrate it.

Same thing goes for temperature surfing, you need a way to check what temp you are brewing at.

Bulk Scace buy anyone?


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## garydyke1 (Mar 9, 2011)

fatboyslim said:


> I have a PID and lately at 101 degrees, which equates to 92 degrees brew temp, I've noticed a lot of steam coming from the group head whilst purging. I'm wondering if the offset value is wrong.
> 
> I think if you are getting a PID you need a way to calibrate it.
> 
> ...


You need to establish the temperature reading which results in just about 'flashing to steam' if this isnt 99c then your offset is incorrect.

Check this out


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## Milesy (Mar 8, 2012)

I have not taken any temp readings but I seem to get the same results whether I just pull without a cooling shot than with.

I have managed to get my extraction at 18g into 30g output to 25 seconds just now with about a 10lbs tamp (estimated). 30g just seems a little too short a shot for me though and that is me stopping when it blondes to my eye. If I run it to 40g output the crema has a large blonde spot in the middle indicating it has definately blonded and the result tastes watery in the mouth.

The cone actually seems larger than when I was doing courser grind and heavier tamp? Is my lighter tamp actually encouraging channeling?

I have managed to get a full flavourful 40g out of 18g beans in the past (a few different favourite blends) so it would be good to be able to figure this out.









thanks


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## MikeHag (Mar 13, 2011)

As always, tough to diagnose over the forum. A flush will make a difference to the extraction, so when you say you get the same results no matter whether you flush or not then that suggests a few things... one of which (of course) is that temperature isn't the issue, so let's look elsewhere.

What I suspect is that this is a grinder issue. I've said this several times, and others will disagree, but I just think that the grind from an Iberital MC2 isn't conducive to a good shot of espresso. Something about the way it grinds means that you have to grind finer than you should to achieve a shot time within the usual time range and with mousetails that look right. It may look ok but those finer grinds result in more migration of fines from the top to the bottom of the basket, and also passing through the basket and into the cup. The result is an uneven extraction (some grinds under, some grinds over) that tastes poor in the cup.

So given the grinder's limitations, what can you do to work around this? Grind coarser, as you were doing previously. Of course this will speed up the extraction, so to slow it down you should do two things. (1) Tamp a little harder... 10lb is very light, so go up to the standard 30lb. (2) increase your dose to 20g. If that means buying a 20g VST basket then I'd say do it, as it will (IMHO) help you get better shots from the MC2 and alleviate the need for a grinder upgrade. The occasional person will laugh derisively at the thought of a 20g shot but the fact is that 20g is the standard in many great coffee shops throughout the US and Australia now, and it is also now the default basket size used in the World Barista Championships. Vince Fedele, who invented the VST baskets and the VST Refractometer recently advised me that (to cut a long story short) this is a good route to achieve the magic extraction yield of 19% for espresso, at which point espresso reportedly tastes sweetest. And a larger dose will also help you attain the volume of beverage you seek.

The other thing, of course, is that it may just be the beans.


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## fatboyslim (Sep 29, 2011)

MikeHag said:


> As always, tough to diagnose over the forum. A flush will make a difference to the extraction, so when you say you get the same results no matter whether you flush or not then that suggests a few things... one of which (of course) is that temperature isn't the issue, so let's look elsewhere.
> 
> What I suspect is that this is a grinder issue. I've said this several times, and others will disagree, but I just think that the grind from an Iberital MC2 isn't conducive to a good shot of espresso. Something about the way it grinds means that you have to grind finer than you should to achieve a shot time within the usual time range and with mousetails that look right. It may look ok but those finer grinds result in more migration of fines from the top to the bottom of the basket, and also passing through the basket and into the cup. The result is an uneven extraction (some grinds under, some grinds over) that tastes poor in the cup.
> 
> ...


That is interesting Mike but I faithfully stick to my 15g VST as I like the lower dose, lower beverage weight/volume and also the economics of using 5g less coffee each time.

Unless roasters would address the issue of using 20g each pop by selling larger packs (but keeping postage low), I'll stick to my 15g VST and get no where near 19% extraction yield









Obviously a good grind consistency would improve yield using the 15g VST? New genuine burrs show real promise, grind is so fluffy and not clumpy (not even seasoned them yet).


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## MikeHag (Mar 13, 2011)

Sorry Mark, was aimed at Milesy really, with his MC2


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## garydyke1 (Mar 9, 2011)

The smaller the dose the closer attention to distribution is required, less room for error. I too love the 15g VST, (the finer grind allows some real intensity and depth of flavour and produces a yield perfect for myself) but im finding using a EP HQ basket with 17-17.5g does not require such obsessive preparation for a good pour (Funka aside) and produces a 'safe result' rather than the potentially exception result from the VST. Must get round to trying an 18g VST for comparison.


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## RolandG (Jul 25, 2010)

Milesy - are you using WDT/yogurt pot & paperclip technique before tamping? My personal experience with an MC2 was that clumping was the biggest issue in terms of extraction.


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## garydyke1 (Mar 9, 2011)

Personally I thought the MC2 produced a pretty good grind quality, the issue as Roland says is clumping/distribution. Saying that now I have moved onto one of the 'big flats' I prefer the flavour profile over conicals


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