# Does a flat bed/slurry matter for conical brewers?



## the_partisan (Feb 29, 2016)

You can find lots of information online that if you're using V60 or similar brewers that you must have a flat bed at the end of the brew or your extraction will be "uneven". It also seems like a recent thing as the original designers of the device in Japan didn't seem to care about having a a flat bed. Is there any actual testing on this (i.e. by taking dry residue from different parts of the brew bed) or is it just one of those things that people take for granted without giving it a thought? Who is not to say that in drip the extraction doesn't happen during drawndown but when hot water makes contact with the slurry (i.e through washing)?

I did a few brews on a V60 like brewer (Origami) without doing a final swirl/tap but just letting drain and it didn't seem to lower EY when doing bloom + two pulse pours. The one without the swirl salso eemed cleaner likely because you're not kicking more silt into the brew?


----------



## MWJB (Feb 28, 2012)

I'm undecided on this. I have had very tasty brews with uneven/pitted beds. With permanent filters like Kone & Hario Cafeor, these seem to be the tastiest.

Until the liquid drains, I see the slurry as just that, a floating/swirling mixture of particles semi-suspended in the liquid, if you pulse pour at a low water level you can see the whole lot churning as you add water towards the end of the brew.

I think it is important to get the whole bed wet at bloom, especially if using a few pulses (lots of little pulses with a coarse grind seem to do OK without a specific bloom), so that particles aren't left dry & excluded from contributing to the brew.

I think there can also be a trade off when brewing fine, or with larger brews, where silt passing through the paper causes bitterness even at normal extraction levels. Here, it can be advantageous to disturb the bed as little as possible to minimise silt in the cup/server.


----------



## the_partisan (Feb 29, 2016)

Yes agree that obviously if grounds don't get wet at all then it's a issue. However I don't think it matters that some ground got wet 10 seconds after another? I think the bulk of the extraction happens very quickly. I did a test brew with 13.5g coffee, 40g bloom and just pour 110g water (I use a 2mm flow restrictor) as a very gentle stream right in the middle. After diluting it still ended up at 18% EY and was very tasty too. The brew time was something like 1:45 perhaps. Then poured another 75g of water on to the slurry and let that drain too in another cup. This part had lower TDS (0.7% or so) and quite different flavour profile. Perhaps the latter stages of brew do contribute little flavour, but it's not major and act mostly for dilution?

Also pouring in spirals seems only worth while for bloom and not for latter stages.


----------



## the_partisan (Feb 29, 2016)

Some of the stuff I'm referring to:


----------



## MWJB (Feb 28, 2012)

the_partisan said:


> Also pouring in spirals seems only worth while for bloom and not for latter stages.


For finer grinds &/or bigger brews, sure. I used to make large (~650g) Melitta brews & just pouring down the middle after pre-wet worked well, but it can slow down the pour. Now, I make 3x 1 mug brews consecutively & it's a little easier to keep to consistent pour timings with spiral pours & maybe grind just a tad coarser.

Sure, for a single brew, just pouring down the middle can work well.


----------



## Step21 (Oct 2, 2014)

I like using the Bonavita immersion brewer for drip. With the valve shut you can pour a generous bloom (say 50g water to 13.5g coffee) and give it plenty of time to soak making sure everything is saturated before opening the valve for the rest of the pours.

With other brewers a generous bloom can seem to run through very quickly and can force larger particles through the filter.

As the majority of TDS is picked up in the bloom and first pour these stages seem most critical?

If you pour with minimal agitation you tend to get flat beds without trying. The bed settles and you get almost clear water above. A final pour with more agitation doesn't seem to overly disturb the bed (unless aggressively hosing)

The Behmor Brazen can leave indentations where the shower head sprays but doesn't seem to cause any problems.


----------



## the_partisan (Feb 29, 2016)

Scott Rao sells a spray head too

https://www.scottrao.com/products/ufo-upgraded-spray-head



> However, the spray head greatly favors the grounds near the center of the coffee bed (evidenced by the large, depressed area in the center of the spent coffee bed). The result is exceptionally uneven extraction, which yields more bitterness and astringency and less overall extraction levels.
> 
> Our goal was to help the machine reach its full potential by improving the evenness of its extractions. Our device produces better and higher extractions by distributing water more evenly across the entire coffee bed.


I have a hard time thinking the manufacturers/designers of this device couldn't figure this out?


----------



## Scotford (Apr 24, 2014)

the_partisan said:


> I have a hard time thinking the manufacturers/designers of this device couldn't figure this out?


To be fair though, all spray heads bar mayyyyybe the Fetco stupid magnetic thing (which is actually pants) feel like they are afterthoughts to the entire machine.


----------

