Hi everyone,

I'd like to talk a little bit about pulse pours, and gather your thoughts. I'd like to explore three variables of interest: total bed height and it's relation to temperature and drain rate

My observations are that manipulating pour technique, and specifically small vs. large pulse pours and slurry height, can have a drastic effect and extraction, and ultimately what ends up in your cup. My primary experience is with the Kalita 155, which may have a different choke point (the small holes) compared to the V60, where the flow rate is more impacted by grind size.

My current thoughts are that smaller (20ml or so) pours are better because this maximizes heat in the bed (more hot water more often). However, one could also argue that 60 or 80 ml pours and heating up the kettle between pours (if you have a variable temp kettle) may also be an effective way to do this. I believe that keeping the bed high allows for higher total thermal mass in the bed as well. Hence my current technique is no bloom/stir, +50, +100, then a number of small +20 pours to keep the slurry at a constant, high height.

I've also noticed that if I keep the water level higher the total drain rate is faster, and if the total water level stays lower the total drain is slow. This makes me think that the water level of the bed has an impact on drain rain, and that keeping the water level within a smaller range will result in a more consistent drain time.

Of course there's also coffee age to consider, as I've observed that this has an impact on drain time as well.

Essentially, I'd like your opinions on whether
1. bed height has an impact on drain rate
2. coffee age has an impact on drain rate (older coffee= slower? possibility due to the coffee becoming brittle and giving a wider distribution of particle sizes?)
3. bed height has an impact on temperature in the slurry
4. pour frequency has an impact on temperature in the slurry

If you've observed these variables impacting one another as well, what has been your technique to manipulate them to get the best cup possible?

"Pour", or "pull"?

If you're referring to pulls, you need to consider what happens when the 3-way valve opens.

Edit: Sorry, disregard. I was thinking this was espresso.

Jack

I aim by looking at how the beans are laid after the coffee has strained. Nowadays I find that having a conical shaped bed of wet grinds at the end. With as much creme/foam staying in the bed as possible and not transfer through in the cup. This has not only cleared up the cup but also taken away bitter notes so actual fruit can be tasted. I also don't pulse I pour continuously medium rate of pour at one line stretching from the start (edge of the dry beans, creeping up so the force of the water churns the beans, to the top of the filter until the entire filter is full. I feel that this increases the maximum rate of outflow and gives the most ability for the beans be dissolved in the water. by increasing the rate of contact with water.

When the water reaches the top I stop pouring, I have averaged the timing and pace of the pour so its almost exactly 18 or 22g for 250mL. I don't presoak and when I start pouring I am mixing the dry grinds and water with a spoon. Usually takes 1:30. It's very quick and very clean. I don't feel it takes away from the body, I've found that issue to be more of the bean characteristic than something I can coax out.

tldr; I think the flow rate is dependent of the grind consistency and height of water in the cone.
The coffee taste, is finding the grind size, flow rate that matches contact of water to end drips around 1:30
Slurry temp variation isn't the issue it's your starting temp in the kettle. (by the time you finish pouring the water may have lost a degree or prob 2. I use temps of 198-202*F

There is a post over at the Brewing sub-forum detailing Scott Rao's single pour and stir method.

I have been trying that, and other than that I need to grind finer, it's much simpler and hassle-free. Works for me when I don't feel like doing kungfu when I'm half-awake.

I do single pour. Its always tasted better to me.

I mostly do 28 g coffee / 450 g water, i end up with 15 oz in my travel vacuum mug


Different batch size requires different style of pour, and grind.

1. bed height has an impact on drain rate
Of course it does; compare a single cup Kalita to a 3 gallon batch brew. But what can you do about the volume of your coffee bed? If you need 24 grams of coffee ground at a certain coarseness and it has to fit in the shape of your brewer, there isn't a whole lot you can do about it

2. coffee age has an impact on drain rate (older coffee= slower? possibility due to the coffee becoming brittle and giving a wider distribution of particle sizes?)
Within the course of a couple months I have not observed this. The process and variety of the coffee has a much greater impact. Example: A very dense Ethiopian bean may take a whole minute or two longer to drain after the last drop of water has been poured compared to a big spongey pacamara.

3. bed height has an impact on temperature in the slurry
No idea but I challenge you to find a way to effectively measure this!

4. pour frequency has an impact on temperature in the slurry
This is the big one, and it depends on a few things. Here at Denver's altitude where water boils at a lukewarm 202 Fahrenheit we have to reheat the water after the bloom and after each of our ~100g pours. There's a lot going on to require this:
A. As you debit water from the kettle the smaller thermal mass retains heat less effectively so you're losing temp fast, and that matters for dense lighter roasted coffees!
B. If you're using a gooseneck kettle, that neck is like a giant heat sink pulling temp from the water.
C. Then, that tiny stream has to fly through the cool air, and then it hits a cooler coffee slurry.

You definitely don't want your slurry level to be rising and falling a lot throughout the brew, but we have to deal with it a bit so we can reheat our water. I imagine there are some takeaways even with hotter sea level water! If you are curious, you can read a bit about the exact way we brew single cups in a blog post I wrote a few months back on our website under the "education" tab.

Thanks for the interesting thread!

Continuous slow single pours seem to net the st consistent cup for me. Just an observation.