Chemex brew stalling

[JPDyson]

Weirdly, my Chemex brews have started taking WAY longer than when I started. I think the first time I ever brewed in the thing, I got almost exactly 4:00 (which I hear is long for this method). Not changing any variables other than coffee variety, my brews this past weekend took 6 and 7 minutes!

I did some reading, and depending on who you believe (namely, Chemex or SCAA) I should be using 40g to 50g of coffee in my 6-cup (30oz) Chemex. Welp, maybe there's a problem - I'd been using between 55g and 60g. Would that cause super slow brew? I did notice that after I bloom the coffee, I'd barely get more water in the funnel before it was "full" (1/2" from the top). I've checked my grind size, and it's on the coarse end. I've also tried stirring, and that doesn't seem to speed it up.

Drip Experts - would using a significantly excessive amount of coffee cause this? FWIW, I'm pre-wetting the filter thoroughly, and using water right at 205. I pour on enough to bloom, wait until about the :40 mark, and then top off the cone by pouring slowly in circular motions. Adding back water when it gets a little low until the desired brew volume is reached, total time seriously between 6 and 7 minutes.

 

[renoles]

I'm some distance from expert but am a big Chemex fan/advocate/user...

I've used slightly more coffee than recommended to no real trouble - biggest causes of stalls to me are too much "dust" in the grind and the filter forming a soft seal in the spout. How fresh is your coffee? I homeroast (from time to time) and have had occasions where really fresh coffee makes for a slow brew.

 

[JPDyson]

I'll check the filter/spout issue; do you think it's back-pressure? As for dust/fines, I suppose it's a possibility. It's just weird that it came on so quickly. Do freshly-roasted beans (I home roast, so they're typically 2-3 days old) gum up a grinder more quickly?

Are folks still using minute rice for that?

 

[Jasonian]

When nothing has changed except for the day, this is most often to do with pour technique.

Pouring down the sides of the filter tends to wash the accumulated fines towards the bottom, thus stalling the flow.

Normal time is 4-5min. It's just a balancing act between grind size and brew time. The finer the grind the slower the flow, so it takes a little experience before you get it right.

Of course, without having watched you brew with a Chemex, it's a guessing game on our end until one of the suggestions works.

Just my $.02.

 

[JPDyson]

Thanks, Jasonian. It could definitely be my pour technique, but wouldn't you agree that a grind with fewer fines would be less susceptible to this type of problem? Perhaps I can clean my grinder and reduce the likelihood of fines (if cleaning your grinder does such a thing). I did two good pours in a row one weekend, and then three bad ones (I did another batch this morning, still 5+ minutes) so it's either my pour or an acute-onset grinder issue.

I'll start w/cleaning my grinder and pouring more carefully.

 

[renoles]

I'm putting forward a hypothesis here...the very fresh beans are still degassing - they do so more rapidly once they bloom and these gases both lift and compress the brew mass (I'm not sure what else to call it) as they are expanding in all directions simultaneously. This may also push the "dust" or "fines" into the filter. I've noted that the occasional stir helps. I also recognize that this may be so much bunk as I haven't tested it in the least.

 

[JPDyson]

If it's a degassing thing, I'd be surprised. I roasted on Thursday evening and brewed Saturday and Sunday morning. Sunday was no better than Saturday (worse, even). Previous weekend, I roasted Thursday and Friday evenings and brewed Saturday and Sunday mornings, both with perfect results. This morning, I brewed beans roasted barely 18 hours before with results better than yesterday (two notches coarser on the grinder - forgot to mention that) but worse that the first two attempts.

I'm starting to side w/Jasonian - I'm a poor pourer (or I'm getting more fines lately). However, can anybody speak to whether cleaning a grinder would reduce the amount of fines, or if minute rice is still a recommendable method for cleaning?

 

[renoles]

I've used rice and grape-nuts to clean grinders. Cleaning the grinder can't hurt.

 

[SiBurning]

I don't think the amount of coffee is the problem, not directly anyway. Different roasts and grinds just work different, and change as they age. They have different amounts of fines and loose oil, and wet differently, and these affect how the grounds work in the filter. If I see a coffee running slow or fast, I use a spoon to nudge it along. Either scraping the sides, or loosening up the sludge. The idea is to disperse the fines and keep them from settling on the filter or causing a heavy sludge. Once you start this, you can't just walk away, but you need to keep at it. For a really slow brew like you're describing, I'd avoid scraping the sides because it only adds more fines into the mix. Another thing I do in a pinch is to lift the filter by two sides, sort of squeezing the coffee out of the bottom, then stir after that. Sometimes I'll use the handle end of the spoon to get further down into the cone of the filter. Just some ideas. To get a grip on it, you'll just have to play with your food.

 

[Jasonian]

If it's a degassing thing, I'd be surprised. I roasted on Thursday evening and brewed Saturday and Sunday morning. Sunday was no better than Saturday (worse, even). Previous weekend, I roasted Thursday and Friday evenings and brewed Saturday and Sunday mornings, both with perfect results. This morning, I brewed beans roasted barely 18 hours before with results better than yesterday (two notches coarser on the grinder - forgot to mention that) but worse that the first two attempts.

I'm starting to side w/Jasonian - I'm a poor pourer (or I'm getting more fines lately). However, can anybody speak to whether cleaning a grinder would reduce the amount of fines, or if minute rice is still a recommendable method for cleaning?

A fact that every coffee lover must learn is that fines are inevitable. It's less to do with a "dirty" or "clean" grinder, and more to do with the sharpness of the burrs and the density of the coffee being ground.

Lower density coffees are more easily crushed, which leads to a tendency to produce more fines when ground.

Similarly, dark roasted coffees are more brittle and tend to produce more fines when ground as well.

Might I suggest a full 1/3-1/2 total volume of water be used for the initial bloom? I generally don't like manual stirring of coffee, as it can very easily lead to over-agitation (which leads to over-extraction).

Second to the coffee and grinder, pour technique is everything.

 

[SiBurning]

I generally don't like manual stirring of coffee, as it can very easily lead to over-agitation (which leads to over-extraction).

Second to the coffee and grinder, pour technique is everything.

There's the problem with my suggestions about stirring. You need to diagnose the issue. If the filter's clogged with fines, or the grinds are forming a rigid sludge or develops a shiny surface, you'll need to break it up to help the brew along. Otherwise, stirring is better at getting a fast brew time to extract better.

One thing... when you pour, try to stay more in the center. Pouring near the sides will pull the fines on the sides of the filter and move them down towards the bottom, which will stop up the works.

 

[JPDyson]

RE: Stirring, tried that - I used a spoon to scoop grounds away from the point of the filter. This seemed to briefly help but quickly lose effectiveness. I had to do it repeatedly, which sounds like it's no better (and certainly not what I want to do the whole time).

I did a fairly thorough cleaning and exam of the grinder; there's significant wear to the burrs. I can pay $40 for a top burr (the bottom one isn't replaceable) or just double down and get the refurb'd Baratza Barista, which does have replaceable burrs (less than $40 for the pair). I think it's a no brainer - I'll relegate this one to backup/work duty and call it a day.

At least if that doesn't fix it, I eliminated a variable...

 

[JPDyson]

Well that'd didn't go as I had planned...

There's a Virtuoso headed my way.

 

[commanderkeen]

Well that'd didn't go as I had planned...

There's a Virtuoso headed my way.

Congrats!

 

[Jasonian]

Well that'd didn't go as I had planned...

There's a Virtuoso headed my way.

Awesome!

 

[Optionyout]

I was reading online that this is a typical problem. What happens is the wet filter forms a vacuum seal. The solution was just to give the filter a little pull off the sides.

Anyone use a gold mesh filter with their Chemex?

 

[JPDyson]

Some guides say try your best to keep the paper sealed to the brewer. Others say to lift it out of the brewer. I'm at a loss as to which is correct, to logic seems to suggest that lifting it out would allow more area for water to escape the filter AND for pressure to equalize (allowing faster filtration).

BTW, I still have this problem with the paper filters and fresh coffee. I'm using the square, unbleached filters. I bought some whole beans from the grocery store recently because I didn't have any roasted beans on hand and needed to brew some coffee, and I can do an easy 3:30-3:45 brew with those (same volumes, sloppy pour and all).

Is it possible that the freshness of the beans is hampering my brew speed?
Edit: I roasted the beans on Thursday and brewed yesterday and today, at 55g to 1000mL of water

 

[Jasonian]

Some guides say try your best to keep the paper sealed to the brewer. Others say to lift it out of the brewer. I'm at a loss as to which is correct, to logic seems to suggest that lifting it out would allow more area for water to escape the filter AND for pressure to equalize (allowing faster filtration).

BTW, I still have this problem with the paper filters and fresh coffee. I'm using the square, unbleached filters. I bought some whole beans from the grocery store recently because I didn't have any roasted beans on hand and needed to brew some coffee, and I can do an easy 3:30-3:45 brew with those (same volumes, sloppy pour and all).

Is it possible that the freshness of the beans is hampering my brew speed?
Edit: I roasted the beans on Thursday and brewed yesterday and today, at 55g to 1000mL of water

Brewing in a Chemex with very fresh coffee is certainly different. A Chemex brew should normally take about 4-5 minutes.

Yes, this is longer than a French Press. No, it isn't significantly more bitter as a result. The open top design of the Chemex brew chamber means that the more water drips through the filter, the less heat is retained.

Just like in a cupping, a gradual tapering off of thermal energy has an effect on the rate of extraction.

How long are your brews taking, anyway?

 

[JPDyson]

Brewing in a Chemex with very fresh coffee is certainly different. A Chemex brew should normally take about 4-5 minutes.

Yes, this is longer than a French Press. No, it isn't significantly more bitter as a result. The open top design of the Chemex brew chamber means that the more water drips through the filter, the less heat is retained.

Just like in a cupping, a gradual tapering off of thermal energy has an effect on the rate of extraction.

How long are your brews taking, anyway?

6 minutes, from first pour "bloom" to pulling the filter and bypassing for desired volume.

 

[Jasonian]

Grind coarser.