Filter clogging prior to full extraction

(Nickolas Fink) #1

Hey all,

First time poster. I use a Kalita wave, baratza vituoso, 15g coffee and usually 255ml water.

My issue is this: I got a bag of Ethiopia (yirgacheffe) with a subscription this month. I’ve had a hell of a time trying to get a drinkable cup out of it. If I grind it as fine as I want to for extraction purposes, it will clog the filter and the drawdown time goes through the roof; the last 25ml alone takes a good 2-3 minutes to pass through the bed of grounds, and the cup ends up powdery and gross. If I open up the grind, the coffee ends up sour and equally undrinkable.

This isn’t the first time I’ve experienced this problem, where the filter seems to clog before the coffee can fully extract. Very frustrating! Can anyone offer some advice?

(jonny) #2

I’m never seen it with Ethiopians, but it is possible to have a very light roast grind differently than a darker one. I haven’t touched my grind settings and between one roast and another (did em myself), stalled my chemex pour significantly.

Your grinder may be creating too many fines…but it’s a good grinder and maybe you’ve not had this issue up til now.

Either way, try the grind in a different grinder and that may help troubleshoot.

(Mike Ward) #3


The reasoning for the coffee taking forever is it’s moisture content. The fresher the coffee, the more moisture it has. The more moisture it has, the less soluble it is. Thus, the coffee lets less water pass through. A hotter water temp might help break the coffee down and aid in the brew. The down side to this idea is that if it’s too hot, it might over extract the finer granules. I usually use 205 F to brew and just bumped it up to 207 F. I have also been trying hard not to force the water in and over fill the brewer. When it first started happening, I kinda dumped water in the brewer to get to the goal weight then letting it over extract/ go over time. The slow pour seems to be working.

(Nickolas Fink) #4

Jonny- Yes, different roasts will grind differently; as I understand it, lighter roasts will be more brittle and more prone to shattering, so will throw more fines, and I’m sure this is contributing to the problem. You should defintitely change your grind settings at least between new coffees, I usually change them every morning to get a better cup than the day before! I don’t have two grinders, but that’s an interesting idea, I’m sure my local shop would play along one afternoon if it comes to that.

All- This is a light roast, but it’s from a roaster who describes the cup as floral and sweet. I can’t find anything close to those flavors. Is it possible it’s just underdeveloped?

(Nickolas Fink) #5

Mike- This coffee is two weeks old, it’s not fresh off the roaster by any means. I’m curious about the moisture content thing… once the grounds are saturated, it would seem like “moisture content” is no longer a meaningful term. Could you explain “the more moisture it has, the less soluble it is” to me? Are you talking about the moisture content pre- or post- roast? As to the rest… I use water just off the boil for every pourover; this keeps the slurry in the ideal temperature for extraction (~195F) for the longest period of time.

PS, I recently got a flow restrictor for my kettle, it makes consistent and gentle pouring much easier, if you’re worried about agitating the bed too much look into that option.

(jonny) #6

I really like the other answer on the forum about high moisture content.
That sounds like the root issue if you’ve really opened up the grind.

Why not take it to shop and have the barista show you how the house would
brew it?

(Mike Ward) #7


Okay, so by fresh I don’t mean freshly roasted. I mean fresh crop. So coffee when it is picked and processed at origin, has a high moisture level. That is the amount of water that exists in the coffee bean itself before roasting. When roasted, the coffees water is mostly evaporated from the bean, but it does still contain a % which results in different brews. I.e. Brewing a super dark coffee will result in a quicker brew time than a coffee that is roasted at a City level.
As the green coffee gets older, it loses it’s moisture and roasts much quicker thus burning off the remaining water in the beans. The older the green coffee, the faster the brew. The fresher the green, the longer the brew.

(Mike Ward) #8

Side note, when I noticed this happening I switched to a different brewing device to get a proper flavor base. I have been using an aeropress lately that has been coming out really good! I use the Wendleboe recipe of 14g coffee to 200g water. Brew for one minute and press. This method is not inverted.

(Nickolas Fink) #9

Okay, that’s how I’ve understood moisture level in the past, was just confused by the wording.

It seems like you’re assuming the roaster is using the same roast profile for each coffee, regardless of how old it is. In professional operations, wouldn’t a roaster compensate for a relatively high or low moisture content (within reason) by applying heat differently to achieve the desired results?

(Mike Ward) #10

Yes, they would adjust the roast so it doesn’t burn the coffee, but the water levels would still be low. If the levels are high, they again adjust to best roast that coffee. Ultimately the water contents would still change over time. Basically the roasters job is to bring out the best flavors in that coffee. The way that they brew on the cupping table vs. the way that they brew in a brewing device are totally different. Jah feel me?

(Prince tarausai ) #11

if you using the Ek43 grind your coffee quiet come 8 to 8.5 most ethiopian coffee they tend to have more chefs and more fines that end up clogging the path and restrict the flow rate and increase brew time end results of over extracted lack body and sweetness

(Haider Adams) #12

Well, it’s not only about moisture content. You said that you’re using kalita, probably 155, and there is a problm with it - old and new version. The old one has the bottom made of metal sticks, the new one has extruted bottom which is litte bit lower than the old one with sticks and I find it easier to clog cause filter is nearer to the hols.

(Nathan DeRuvo) #13

Underdevelopment is what it sounds like to me! Or they are roasting to very different water.

(Eric Nadler) #14

If you are stirring the coffee you could try not stirring. Sometimes I’ll see super long draw downs if I stir too hard, but I do usually see that more on my Clever than on my Kalitas.

Just, curious, which Kalita are you using and what grind setting? I have two Baratza Preciso grinders so I was just curious if you use a lot finer grind than I normally do. I probably grind coarser than most. With my Kalita 155 I’m usually in the 18 to 24 grind setting with my current staged pour recipe.

(Nickolas Fink) #15

Ok, got this worked out. You nailed it actually, I was grinding way too fine. I contacted the roaster, and he said he grinds this coffee fairly coarse in general, a little finer than French Press. It was really strange, I usually end up around 15-20 (out of 40 on the Virtuoso) for a pourover, but this range was producing SUPER sour flavors, so I kept tighting up the grind to extract more. Once I tried opening it up more, it was up to a 30 before it tasted good and a 35 before I got any sweetness out of it! Never would have expected that from a dense, light roasted bean, especially one that was so sour at finer grind. Where’s my understanding failing me?

PS- Mike I feel ya, they can adjust somewhat but can’t compensate for all of the effects.
Prince- That makes sense with the chaff.
Haider- I have both, at around 20g dosed I’ll upsize, depends on how much I’m making

(James Bodington) #16

@nickolas.fink I’d be interested to hear where people think Nick’s understanding is failing him.