Wetting the filter

[Curlz]

When I was in Chicago a couple of weeks ago, I bought a pound of Intelligentsia coffee. Was actually reading the bag yesterday, and it says to wet the paper filter with hot water before putting the coffee in. I had never heard of this, and wonder why they recommend it. All I could think of was that there was somehow less shock when the water hits it, but I'm just making sh*t up, so I'm turning to you all for the real answer!

[JayBassin]

If you percolate water through dry coffe grounds in a dry filter, the water "wets" grains and follows inter-grain channels to the filter. Water will flow through these wetted channels preferentially. The first patches of filter that feel the water will wet, and due to surface tension, subsequent water will flow through the initially wet patches. The rest of the filter may take a few minutes to saturate. Therefore, the initial flow of percolated water will follow the same narrow inter-grain channels rather than spreading out evenly to saturate the dry coffe quickly.

[phaelon56]

I'll give you my educated guesses but undoubtedly there are more complex reasons than I'll offer up. Keep in mind that many of the recommended practices for brewing coffee are based on years of trial and error experiments and data logging by folks far brighter and more patient than I am

It's an accepted fact that paper filters trap some of the essential oils that can provide certain flavor components of coffee. A primary benefit of press pot and vacuum pot coffee is the presence of such oils. But many of us prefer drip coffee based on taste profile or convenience factors.

It's also an accepted fact (but a more subtle difference and not as detectable to everyone) that paper filters impart a subtle "papery" taste to the coffee. Additionally - white paper filters have been whitened by a bleaching process.

Unbleached (brown) paper filters avoid possible taste artifacts due to the chlorination of the bleaching process.

And what of pre-wetting in general? What's the dillio?

1) pre-wets the paper so that any essential oils which can pass through a paper filter are less likely to be trapped during the onset of the brew process

2) pre-wetting and waiting a few seconds before adding the coffee also should lessen any possible impact of the "papery" taste by allowing a few volatile production residue components in the paper to be activated by the hot water and released into the air before coffee is added. Especially important for bleached (white) paper filters.

It's also recommended, when brewing drip manually (e.g. Melitta or Chemex) to pre-saturate the coffee with a small initial amount of water and then finish pouring in the balance a moment later.

Disclaimer: this info is not in the widely accepted Coffee FAQ but it's what I believe to be the case based on reading I've done. I also accept many such practices as valid because if I follow them all my coffee seems to taste better and if I don't... it's not as good!

[GordonCooks]

That's good info - Something I've always meant to ask

[phaelon56]

If you percolate water through dry coffe grounds in a dry filter, the water "wets" grains and follows inter-grain channels to the filter. Water will flow through these wetted channels preferentially. The first patches of filter that feel the water will wet, and due to surface tension, subsequent water will flow through the initially wet patches. The rest of the filter may take a few minutes to saturate. Therefore, the initial flow of percolated water will follow the same narrow inter-grain channels rather than spreading out evenly to saturate the dry coffe quickly.

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There you have it. When I said this...

I'll give you my educated guesses but undoubtedly there are more complex reasons than I'll offer up. Keep in mind that many of the recommended practices for brewing coffee are based on years of trial and error experiments and data logging by folks far brighter and more patient than I am 

Jay must have already been posting. It would seem that the more complex explanation makes more sense (at least to me) and I defer to the more sensible answer that Jay offers.

I think it's NOT very common in commercial environments to pre-wet the filter - most likley because it takes a few extra seconds. That might also be why some of the "extractor" units such as the Fetco CBS 32 series have a programmable delay time between the end of initial grounds saturation and the time that brewing actually starts.

Jay - do you think a slightly prolonged delay after initially saturating the grounds might help to reduce the "channeling" effect?

[JayBassin]

Jay - do you think a slightly prolonged delay after initially saturating the grounds might help to reduce the "channeling" effect?

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Saturating the grounds before brewing starts would ensure that the entire volume of grounds contributed to the brew for the entire brewing time. Wetting the filter helps speed up the flow of water through the grounds. Wetting both the filter and the grounds before brewing would be ideal.

[Curlz]

You guys ROCK! Of course, I figured there was a great explanation for this, but this info has really opened my eyes. I can't say that I'm a serious coffee drinker/maker, but I do enjoy the daily cup (or two), and when I have great coffee when I'm out (i.e. the Intelligentsia--I drank 4 cups--both reg and decaf that day), I realize how EH my coffee is at home. I do own a press pot and will try making the Intelligentsia in it this weekend. I thought you had to have a special grind of coffee to use it, which is why it sits in the cabinet for long stretches, but that's obviously not the case. Thanks again for some great info!

Curlz

[JayBassin]

If you have potted plants in the window sill, you've probably read that it's best to water them by putting them in a dish of water and allowing capillary action to draw the water up from the bottom. If you pour water from above into a pot with dry potting mix, the water will trickle through fissures and flow out the bottom without wetting all the soil It's the same principle in a coffe filter. Ideally, you'd saturate the filter and grounds from below and allow capillary action to pull hot water up, but I don't know of any coffee machines that operate that way. Second best is to allow the water to sit in the filter, saturating the grounds, before beginning the brew.