Do wet filters change the hand brewed coffee methods you use?

Wetting the filter paper before pour-over serves three main purposes: rinsing away off-flavors the paper may have absorbed, preheating the dripper and server, and helping the paper sit flush against the dripper walls. It is not mandatory. A barista at Front Street Coffee was once asked why one brewer rinsed the paper while another started pouring straight in on the same bar.

Rinsing has trade-offs. A wet filter can hinder degassing during the bloom, start extracting grounds early and absorb some water, which shifts the hand brewed coffee methods you rely on. Hot pour-over usually calls for a rinse, while iced pour-over is often brewed directly, so the beverage filter paper market keeps offering choices for each recipe being followed.

Should you wet the filter paper before pour-over coffee or not? This question seems simple, but behind it lie multiple factors such as filter paper odor, dripper preheating, and extraction uniformity. A barista at Front Street Coffee was once asked by a customer why, when brewing iced pour-over and hot pour-over simultaneously, one had the filter paper wetted while the other was brewed directly. This article will start from the three main purposes of wetting the filter paper—rinsing away off-flavors, preheating the dripper and server, and helping the filter paper adhere to the dripper—then further analyze the possible effects of wetting the filter paper, such as hindering degassing during blooming, premature extraction of coffee grounds, and water absorption by the filter paper. Finally, it will explain why hot brewing and iced brewing handle the filter paper differently, helping coffee enthusiasts make more suitable choices based on actual circumstances.

One day, when a barista at Front Street Coffee was brewing iced pour-over and hot pour-over at the same time, a customer curiously asked, "How come one of you wet the filter paper while the other started brewing directly without wetting it?"

So, is wetting the filter paper really a mandatory step before brewing? If it is not mandatory, under what circumstances should the filter paper be rinsed? To understand the reasons, let Front Street explain them one by one below.

What exactly is the purpose of wetting the filter paper:

1. Rinse the filter paper and remove off-flavors

Some friends might think 🤔️, aren't there already paper-taste-free filter papers on the market that use bio-enzymatic bleaching? As long as the filter paper brand you choose is reliable enough, this issue should not be a concern.

But one point is easily overlooked—how do you usually store your filter paper? What are the storage conditions like? Front Street has encountered situations like this: a friend left the filter paper openly on a shelf, and he himself smoked heavily, often smoking alone at home, so it is obvious what smell the filter paper would end up absorbing.

It can be said that "paper-taste-free filter paper succeeds because of being odorless, and also fails because of being odorless." Precisely because the filter paper itself has no smell, it more easily absorbs surrounding odors. Of course, if you always keep the filter paper sealed and stored separately, there is no need to worry about this.

2. Preheat the dripper and server

The necessity of this depends on the material of the dripper you use. If you use a resin dripper, it does not absorb heat itself and has weak heat retention, so whether you preheat it has little effect on the extraction result; but if you use a ceramic dripper, then preheating the dripper while wetting the filter paper is very necessary. (Friends who want to know about the heat retention of dripper materials can: click here)

Preheating the sharing pot, meanwhile, can ensure that the temperature of the coffee liquid does not drop too much after extraction is completed, so you can better appreciate the coffee's flavor.

3. Make the filter paper fit the dripper

If you are not very confident in your filter-paper folding technique, you can press the filter paper with your hand and then pour water to wet it, which helps the filter paper sit more snugly against the dripper. Of course, if your technique is not up to par or the filter paper and dripper themselves do not match, it still will not adhere firmly even after wetting.

If you pursue more uniform extraction and want to reduce interference caused by the filter paper, then the following three points about filter paper are even more worth carefully weighing.

1. Blooming and degassing.

After the filter paper gets wet, it becomes soft and clings tightly to the dripper wall. The dripper's grooves can no longer prop up the filter paper, which affects the degassing effect during blooming.

2. After the filter paper is wetted, adding coffee grounds will cause premature extraction.

"Extraction" begins the moment coffee grounds contact water. If you first wet the filter paper and then pour in dry coffee grounds, the portion of coffee grounds near the filter paper will be moistened by the remaining water. Doesn't that mean part of the coffee grounds starts extracting early?

3. The water absorption of the filter paper.

A sheet of filter paper can absorb about 8g of water. If it has already been fully moistened with water, the brewed coffee liquid will no longer seep upward, so after wetting the filter paper and then brewing coffee, the filter paper basically remains close to white; conversely, if the filter paper is not wetted, the coffee liquid will seep into the filter paper. This phenomenon is especially obvious when brewing dark-roasted beans, and you can see the coffee-colored liquid creeping upward little by little.

Returning to the customer's question at the beginning, now you should understand why Front Street handles the filter paper differently for hot brewing and iced brewing, right?

Front Street Coffee

No. 10, Baoqian Street, Yandun Road, Dongshankou, Yuexiu District, Guangzhou, Guangdong Province

The above content is compiled by CoffeeHunters, a coffee news website.