What Mesh Size Should Be Used for Pour-Over Coffee Metal Filters? What Are the Differences Between Metal Filters and Filter Paper? How Many Microns Does 400 Mesh Equal?

Thanks to their all-around performance, paper filters have become the mainstream filter medium for pour-over coffee today. But they're not the only option — beyond paper, there are also filtering tools made from flannel, metal, and other materials.

Each material behaves differently, and to brew a good cup with any of them, you first need to understand how it works. Flannel has been covered at length elsewhere, so today FrontStreet Coffee will focus on how to brew a great cup with a metal filter.

The Pros and Cons of Metal Filters

The metal filter FrontStreet Coffee uses is just a random online purchase, rated at 400 mesh. It's shaped like an inverted cone with a flat bottom and has two layers — the inner one is the 400-mesh filtering screen, while the outer layer simply holds it in place.

400 mesh corresponds to a particle size of 38 micrometers — a very fine pore size. Even if you shake the grounds after pouring, very little sediment makes it through. Still, that pore size is larger than a paper filter's, and this leads straight to one of the metal filter's key advantages: like flannel, it lets coffee oils pass into the cup, which is a real upgrade for the coffee. Those oils carry oil-soluble aromatics, adding fragrance to the cup, and they also build mouthfeel, giving the coffee a fuller body. Paper filters can't do this — they filter so aggressively that they strip the oils out along with everything else.

Metal filters have another selling point: they're reusable, which makes them eco-friendly and economical. Like flannel, they just need a rinse and a dry after use. At one cup a day, the filter pays for itself in about 100 days. Now for the downsides — which, like the upsides, come from those pores. The same screen that passes oils also passes fines. Coffee particles smaller than 38 micrometers are plentiful in most grinds, and they slip through easily, muddying the texture and taste of the cup.

If your grinder isn't especially consistent and you plan to brew with a metal filter, it's worth sifting out some of the fines with a flour sifter first — the negative impact of excess fines is not to be underestimated. With that covered, let's brew a cup and walk through what to watch for along the way.

Brewing Guide

One thing to know before you start: a metal filter's flow rate increases as the water level rises. In other words, the higher you pour, the faster it drains. FrontStreet Coffee's testing found that at high water levels, metal filters drain much faster than a V60 — and too fast a flow cuts the contact time between water and grounds, easily leading to under-extraction. So during brewing, keep your pour gentle and don't let the coffee bed and water level climb too high, or you'll risk a thin, bland cup.

For this brew, FrontStreet Coffee used a washed Yirgacheffe — Guddina — with the same parameters as when brewing it on paper:

• Coffee dose: 15g
• Grind size: EK43 setting 10, 80% pass-through on a #20 sieve — roughly fine sugar texture
• Coffee-to-water ratio: 1:15 (15g coffee with 225ml hot water)
• Water temperature: 92°C
• Pouring method: three-stage pour

Step one is still the bloom: twice the coffee's weight in water, for 30 seconds.

After the bloom, pour the second stage — 120ml total, in wide circles. Since we need to keep the water level from rising too high, use a small flow here, and when circling, avoid hitting the edge of the filter, which causes bypass water.

Once the liquid has fully drained, pour the third stage — 75ml, again with a small flow. This stage's target is the bottom layer of grounds, so narrow your circling range and focus on the center.

When the liquid has fully drained, remove the filter cone and the brew is done! Total time: 2 minutes 5 seconds — about 10 seconds faster than brewing Guddina on paper. The cup was lovely: delicate white florals, fresh lemon, and a clean green tea finish — a very true-to-type Yirgacheffe. And thanks to the oils, this Guddina had an even more impressive body and a longer aftertaste than usual. Quite excellent.

FrontStreet Coffee Recommendation

The star of this brew, FrontStreet Coffee's washed Yirgacheffe Guodingding (Guddina), comes from Ethiopia's top G1 grade and is a classic choice for pour-over: after a medium-light roast it shows elegant white florals, citrus, and orange with a green tea finish — clean, bright, and perfect for showcasing delicate aromatics through a metal filter.

If you'd like a bolder cup to contrast, FrontStreet Coffee's PWN Indonesia Golden Mandheling brings herbal, spice, and dark chocolate depth with a rich, full body — and those oils a metal filter preserves would suit it beautifully. For something in between, the sun-dried Ethiopia Huakui (Flower Queen) offers lush tropical fruit — strawberry, passion fruit, jackfruit — with very little bitterness, great for pour-over or cold brew.