Filters 101 (Paper, metal and cloth)

Make this into a reference note and compare against James hoffman video on cloth filter.

Less Oil <---------------------------------> More Oil
Paper Cloth Metal

Paper

Flavor Profile: light, crisp, bright, clean
Cleanup: quick, convenient
Waste: high

Paper filters offer a fairly clean cup (oils are full of flavor, sure, but they're not necessarily full of the "best" flavors), which can allow for a great layering of nuances, and many paper brews will pair well with fatty foods like donuts or pastries. One of the main downsides is that many paper filters require a good bit of pre-rinsing to get rid of the paper bag taste, especially unbleached brown filters. Not everybody can detect or actually cares about the papery taste, but I personally can't stand it, so I usually run a liter or so of water through most paper filters before I brew. Protip: Kalita 103 Shop filters are amazing and worth the money. They're a tiny bit dusty, but even brewing with them dry has a significantly lower paper taste than anything else I've tried.

Paper filters are tightly woven and absorbent, filtering out most of the oils and micro-grounds. This is a good and a bad thing. On one hand, the absence of oils and micro-grounds produces a thinner, more approachable drink that’s free of sediment. However, the coffee loses a lot of flavors and aromas without those things present, and the lack of microscopic grounds tends to make the acids seem more pronounced and strong (even though they’re not actually stronger - it’s a perception thing).

Metal

Flavor Profile: aromatic, bold, rich, heavy
Cleanup: 30 to 60 seconds
Waste: zero

Metal filters, depending on construction, add a good deal of body to the brew, and typically some sediment. This is the rich cup you get from a french press or Kone filter, it's got a head of oil, it's possibly a bit more astringent or bitter, and it has the potential to overextract a bit. Still, waking up on Saturday morning to a fresh mug of a really rich brew is a thing of beauty. Plus, metal filters are permanent and easy to maintain, requiring perhaps a bit of brushing to loosen stuck grounds, regular rinsing, and sometimes a soak in detergent of some kind - dish soap is fine.

Metal filters create brews with fuller bodies and stronger flavors, because they don’t filter out as many oils or fines as cloth filters do. The oils contain a coffee’s flavor notes, while the fines enhance a cup’s body. Metal filters may slightly affect a coffee’s taste by imparting their own, mildly metallic flavors. Many coffee drinkers are willing to overlook this slight disadvantage, appreciating the fuller notes and bigger body that metal filters provide.

Metal coffee filters brew coffee on the complete opposite end of the spectrum compared to paper coffee filters. Since there’s no finely weaved paper to absorb the natural oils or catch the microscopic grounds, some of these things end up in your final mug. Coffee’s natural oils are responsible for the majority of the aromas that coffee can have - over 800 of them! These oils are barely noticeable texture-wise, but they contribute a huge amount to the overall flavor experience. Many flavors are only possible when coffee oils are present, including blueberry, rose, and many other lighter, sweeter flavors.

Cloth

Flavor Profile: aromatic, clean, bright, medium body
Cleanup: 30 to 60 seconds
Waste: minimal

Cloth is a happy medium between paper and metal, offering a cleaner cup than a french press, but a bit more body than a Chemex or V60. The cloth will absorb some oils, but it's more porous than paper fibers, and will let more oil through, with typically no sediment. Imagine if that four hour old pot of coffee at the office actually tasted good, and you've got approximately what cloth has to offer - a smoother flavor profile, a good body, traces of oil on the top of your cup, and a great clean finish. I've found cloth brews can have a more pronounced sweetness as they cool, perhaps due to the balance of oils against the tang of the acids that extract, allowing other flavors to show their stripes. Cloth, however, is a high-maintenance product. The absorption of oils means the potential for rancidity ruining your cup. Storage and clean up habits will vary, but some insist you should clean a cloth after every brew, others say after every five, or once a week, something like that. The bottom line is that cloth will need to be cleaned to prevent it from ruining your cup of coffee. I like to store my cloth in the fridge, fully submerged in water (ziploc bag will do it, I use a small tupperware), and clean in unscented Oxiclean once a month - again, this is with low usage, maybe once a week. If you're thinking about a nel dripper or coffee sock, or even a vac pot, keep the filter maintenance in mind, because it will ruin your brew if left to spoil.

Cloth filters produce a lighter, sweeter coffee than metal filters. Although they subdue flavor notes by filtering out some oils, they also catch more small particles, or fines. These particles add a slight sharpness to a cup, a flavor French press drinkers are familiar with. By filtering the fines out, cloth filters both brew a clearer cup of coffee and one where sweet notes aren’t counteracted by bittering particles.

Cloth coffee filters are the least common filters among the three - at least in North America - but they’re no less incredible. The finely weaved cloth catches all of the coffee grounds, even the micro grounds, but barely absorbs and coffee oils. The result is a clean, sediment-free cup with rich aromatics from the oils and a high perceived acidity. Sometimes the oils produce a medium mouthfeel. Cloth coffee filters are a good middle ground flavor-wise between paper and cloth, but they’re difficult to maintain. If you decide to go with cloth filters, you’ll need to make sure you wash them very well between brews and don’t let them dry out too much or stay too moist.