Better Understanding of Percolation Brewing Dynamics, Burr Geometry and Coffee Selection

[JonathanMichael]

Hello All,

I hope this thread can become a useful place to share one another's thoughts and experiments regarding percolation brewing methods for filter coffee. This may sound like basic or well-worn territory but I actually feel it's quite the opposite and takes a tremendous amount of testing and tasting to arrive at meaningful and robust conclusions.

As we all know, some of the key variables that impact an extraction are as follows:

-Coffee used
-Water used
-Grind size
-Grind geometry/texture resulting from how different burrs cut coffee
-Brew water and Brew slurry temperature
-Agitation
-Dripper design / flow rate
-Filter material / flow rate
-Bed depth / dose

In particular, I would like to better understand grind size optimization for a particular burr geometry and coffee.

A questions that often nags at me is how to best approach grind size and corresponding brew techniques. For example, you can arrive at similar TDS with a coarse grind size and aggressive agitation as you would with a fine grind and limited agitation. Or you could have a similar TDS with using a very fine grind using a fast flowing dripper and filter combo vs a slow flowing dripper design with longer contact time and coarser grind. Also, of course, pouring structure is another variable here. We all know that you can get to roughly the same point using a very coarse grind and multiple pours as you can with a single pour and a finer grind. We also know that they will taste quite different. Along these lines, I have been wondering if there are certain approaches that play to the strengths of particular burrs sets? For example, a Fuji Royal with its shark teeth burrs might be extremely well suited to a coarser grind size and higher agitation creating lots of vibrancy and complexity. On the other hand, 98mm Brew or Shuriken Coarse burrs might be more optimized for finer grind sizes and higher extraction brewing approaches. These are not suggestions or conclusions...just an example of how we can look at these types of questions and try to test them.

It seems so many push finer grind sizes and higher EY brews. However, I often find them less interesting even using really high quality grind texture, good water and good technique. Currently my main filter brewing grinder is a MAX with Shuriken Coarse. I primarily use April Brewers (with Patrick's technique), Kono drippers, and plastic v60s. I have two of each these and two scales. Typically if I try to compare a variable I'll brew simultaneosly then pour into cupping bowls labeled on the bottom with a dry erase marker.

For the purposes of these discussions, and to eliminate some variables, perhaps we should focus on high quality light roast washed process coffees.

So just to kick things off, fine and fast or coarse and slow? What are your preferences? Do you prefer certain burrs with coarser grind?

I hope we can cover some interesting experiments and share each others thoughts here.

Jonathan

[soulson]

TDS is Total Disolved Solids. Disolved Solids are Magnesium, Calcium, Sodium, . . minerals that ARE ATTACHED to the water molecule. Removing them requires Reverse Osmosis filtering.

TSS is Total Suspended Solids which is what you get when using water for extraction. The suspended solids CAN BE filtered out using fine filters (not coffee filter which are designed to let some solids thru).

TSS & TDS have VERY specific meanings in water chemistry and ARE NOT interchangeable.

[EvanOz85]

Great post Jonathan, and I think in an in-depth thread like this is a good idea.

I recently met up with Jonathan and had a tasting at his place. He brewed several small cups for us with an extremely coarse grind size that I *never* would have even considered for single cup pourover. We used both 98mm SSP Brew on a Titus Nautilus and 98mm Shuriken Coarse on a Max for the cups. I was shocked by the depth of flavor and sweetness that these brews produced.

I've since started using much coarser grounds in my own pourovers at home with fantastic results. Much better cups than I was getting at "traditional" V60 coarseness levels. However I have only tried this so far with brew-centric 98mm burrs and SSP Unimodal V1's...all high clarity/high extraction burr sets. Not sure how well this would translate to other burr styles.

[JonathanMichael (original poster)]

Thanks Evan! It was fun getting together.

There's no question the coffees you are working with and your grinders play a huge role here. I hope, over time, we can figure out how to play to the strengths of certain grinders/burrs and drippers.

[jesse]

I think dialing to a burrset is a valid approach, especially for lower-end grinders that produce greater amounts of fines: This principal is kind of what Lance built his latest hand-pour technique around.

Once you move into higher end equipment and fines are a matter of choice, I guess the idea would be to target what appears to be a grinder's distribution sweet-spot, then dial your brewing variables accordingly for the desired EY & TDS?

This topic would gain a lot of traction on the Espresso Aficionados discord, by the way.

[JonathanMichael (original poster)]

Good idea Jass. Maybe I'll just let me know it exist over there.

Thanks