What is a Double-Chamber Filter Paper? How to Brew Coffee with "Mandarin Duck Pot Filter Paper"? How to Make Pour-Over Coffee?

Introduction to "Yuan Yang Pot" Filter Paper

Every so often, innovative coffee equipment emerges in the coffee community. Beyond the continuously evolving coffee beans, the arrival of these new tools might be FrontStreet Coffee's greatest interest. They always bring numerous novel approaches, making our coffee brewing experience more enjoyable.

Recently, FrontStreet Coffee's attention has focused on a filter paper launched last year, as its design truly differs from conventional ones. How unique is it? Well, we can enjoy a "yuan yang pot" experience in pour-over coffee. When opened, this filter paper has two separate spaces to accommodate coffee grounds, and since it's identical in shape to the yuan yang pot (split pot) in hot pot, it has been jokingly called the "yuan yang pot filter paper" by netizens online.

Its original name is "Dual Chamber Filter," a product developed by Spanish coffee equipment manufacturer Sibarist. The biggest difference between it and conventional filter papers lies in the "partition wall" designed in the middle of the filter paper, which divides the filter space into two. From the official video released, FrontStreet Coffee discovered that this filter paper's partition wall has a higher density, making it difficult for hot water poured on either side during brewing to penetrate to the other side. Therefore, it can truly be called a "wall." So FrontStreet Coffee planned to order a pack to try, but suddenly, FrontStreet Coffee discovered...

30 sheets of dual chamber filter paper, priced at €37.44... which converts to about 283 RMB, averaging "9.4" yuan per sheet! Just think how many bags of coffee beans that could buy!!!

No wonder there are hardly any reviews of this filter paper online. For a disposable consumable like filter paper, this price is indeed somewhat outrageous and not suitable for ordinary consumers. If you're also struggling like FrontStreet Coffee with whether to spend so much on filter paper, why don't we first create a budget-friendly version to experience it and see if this "yuan yang pot filter paper" is truly worth the high price?

Creating a Budget-Friendly Alternative

Making the budget-friendly version is very simple—just use two size 01 filter papers in a size 02 conical dripper. The specific method is to fold two filter papers normally, then insert them face-to-face into the dripper, and voilà—your budget-friendly "dual chamber filter paper" is complete.

However, if we want better isolation effects, like the filter paper partition wall in the official images that can prevent coffee liquid penetration, we can use non-woven filter paper made of special materials, because filter paper is difficult to penetrate when not in contact with coffee grounds.

What to Consider When Using "Yuan Yang Pot" Filter Paper

After we replicated the filter paper, we'll find that the problems to face are much more than imagined. You can try to imagine online—how should such a unique filter paper be used and brewed?

As you can imagine, the "yuan yang pot" filter paper was obviously invented so that beans with different characteristics (such as different roast levels) could be concentrated in one brew. After all, if all coffee beans have consistent characteristics, we could simply mix them together after grinding and brew them, without the need to deliberately separate them. However, coffee beans with different characteristics require different extraction parameters, and among all parameters, the one we most need to solve is water temperature.

Because water temperature cannot be frequently adjusted during the brewing process, if we're brewing two coffee beans with significantly different roast levels, we need at least two kettles. Preferably temperature-controlled ones, because if they're not temperature-controlled, our water temperature control will be very troublesome. That's the first point.

After solving the water temperature issue, we then face brewing problems, which are also the main issues. For brewing, since we need to brew two different coffee beans simultaneously, we need to continuously switch kettles during brewing. At the same time, we need excellent calculation skills, because both beans are in the same dripper, sharing the same electronic scale, so the water amounts for both beans will be cumulative.

Therefore, before brewing, we need to list the brewing plan in advance; otherwise, it will easily lead to deviations from the target coffee-to-water ratio. Because of this, the "dual-person pour-over" (two people brewing the same pot of coffee together) mentioned by netizens in the comments section cannot be implemented (unless using some seasonal brewing method). The above are the points to note when using this unique filter paper (just things to note—specifics should still be determined based on actual brewing situations). Next, FrontStreet Coffee will demonstrate the unique brewing method for this "yuan yang pot filter paper," for reference only!

How to Use the "Yuan Yang Pot" Filter Paper

Since the two coffees to be brewed will mix directly (that is, blend), we need to find two beans that can match and complement each other in flavor and mouthfeel. The blending techniques FrontStreet Coffee shared before can be useful here! Here FrontStreet Coffee tried three blending combinations and shared them with customers and friends in the store for tasting. The combination that received the most praise was: Mozart * Kaffa (Mozart 13g, Kaffa 7g). Parameters are as follows: Grind size: Mozart at EK43 setting 9.5; Kaffa at EK43 setting 10. Brewing water temperature: Mozart at 90°C; Kaffa at 92°C. Coffee-to-water ratio: 1:15. Brewing method: Three-stage pour. Dripper used: V60 (size 02)

When all preparations were complete, FrontStreet Coffee chose to start with Kaffa. First, pour 20ml of hot water for a 30-second bloom (start timer when pouring water).

When the time reaches 20 seconds, we start blooming Mozart, so that when we finish pouring water for Kaffa next, Mozart will also complete its bloom. The water amount used for this bloom is 25ml, and the electronic scale will accumulate to 45ml.

After finishing Mozart's bloom water, the time reaches 30 seconds, and now we can pour the second stage of hot water for Kaffa, 50ml (the scale will go to 95ml). Since the dripper space is divided, we need to reduce the water flow and increase the pouring position during pouring to apply sufficient agitation to the coffee. After finishing, the other side also completed blooming, so we switch kettles again to pour Mozart's second stage of hot water, 100ml (the scale will go to 195ml); after finishing, switch kettles again to pour Kaffa's final stage of hot water, 35ml (the scale will go to 230ml); finally, switch kettles again to pour Mozart's final stage of hot water, 70ml (the scale will go to 300ml). At this point, brewing is complete.

Total time: 2 minutes 15 seconds. The coffee's main flavor is still Mozart itself, and because of Kaffa's addition, the coffee's flavor complexity is enhanced, making the mouthfeel rounder and cleaner. (Indeed quite good) Although we ended up with a fairly good coffee experience, the series of preparations from start to finish were very cumbersome. Whether it's controlling water temperature, selecting coffee beans and their ratios (I grabbed a few groups of lucky customer friends to test and error, next time I'll dare again ), parameter calculations during brewing, etc.—no joke, it's very troublesome. Unless using coffee beans with high similarity in aspects like roast level and processing method, you could use consistent water temperature, which would save much trouble. But as FrontStreet Coffee said, if we make such a choice, it would be more convenient to mix them all together and brew as usual.

But this might also be because FrontStreet Coffee hasn't discovered the true potential of this filter paper, so why don't you also imagine and experiment with what other ways this special "yuan yang pot" filter paper can be used~

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