Reference extraction log from Bunker Company's Seungkyu Park. Despite the very fine grind, I increased the dosing to prevent overly large headspace. On a manual slayer machine, I did a generous low-flow pre-infusion via the needle valve, checked the machine pressure when coffee droplets formed on the bottom of the bottomless, and moved on to the main brew.

The EC log has a unique shape. It's almost linear, 45ยบ, and the fact that the initial EC is not low despite the fine grind seems to be due to sufficient pre-infusion.

The initial flow rate is 0.7 g/sec and the secondary flow rate is 1.3 g/sec, which is a very low extraction flow rate compared to typical brews. The final extraction amount is 45 grams, which is typical. However, the total brew time is very long at 43 seconds. (not including 20 seconds of pre-infusion) It can be seen that the extraction is stable with no noticeable instability, despite maintaining a fairly high resistance for a long time. Stability is also seen in the EC, but the flow rate shows no bumps.

The initial flow rate is 0.7 g/sec and the secondary flow rate is 1.3 g/sec, which is a very low extraction flow rate compared to typical brews. The final extraction amount is 45 grams, which is typical. However, the total brew time is very long at 43 seconds. (not including 20 seconds of pre-infusion) It can be seen that the extraction is stable with no noticeable instability, despite maintaining a fairly high resistance for a long time. Stability is also seen in the EC, but the flow rate shows no bumps.

The second half flow rate is 1.5 g/sec, which is a very slow extraction compared to a typical extraction. The final extract weight is 43 grams, which was extracted for about 38 seconds. (not including 20 seconds of pre-infusion) Compared to the previous extraction, there is a very slight bend in the EC and a slight irregularity in the flow rate, but still no instability for a very long time.

The second half flow rate is 1.5 g/sec, which is a very slow extraction compared to a typical extraction. The final extract weight is 43 grams, which was extracted for about 38 seconds. (not including 20 seconds of pre-infusion) Compared to the previous extraction, there is a very slight bend in the EC and a slight irregularity in the flow rate, but still no instability for a very long time.