Chemex

Why the filter matters more than the glass

Tendency, not a guarantee

The filters are made for this brewer and are heavier than standard papers. Thicker paper holds back more oil and more fine particles, so the coffee is clearer and lighter in texture than the same recipe through a thin cone filter. It also slows the flow, which is why the usual advice is a somewhat coarser grind than for other pour-overs.

Most are supplied as a folded square or circle that opens into a cone with three layers on one side and one on the other. The three-layer side goes against the pouring spout. If the paper collapses into the spout it seals the air channel and the brew stalls, so the thick side is there to bridge it.

Sizes, collars and handles

Widely documented

It is sold in several sizes, labelled in cups that are small ones rather than mugs. The larger sizes share a filter; the smallest takes a different, smaller filter, so check which you are buying papers for. A large Chemex brewing a single cup works poorly, because a small dose makes a thin bed in a wide cone.

The classic version has a wooden collar tied on with a leather cord, which is the heat-proof grip. It comes off for washing. Other versions have a glass handle instead and can go into the sink without being dismantled. The glass is thin and the vessel is tall; treat it as breakable.

Keeping the inside clean

Widely documented

1. Lift the filter out by its edges once it has drained and compost or bin it with the grounds.
2. Rinse the vessel with hot water straight away, before coffee oil dries onto the glass.
3. Use a long bottle brush for the lower chamber. A hand does not fit through the waist of most sizes.
4. Remove the wooden collar and its tie before washing with detergent. The maker says the glass can then go in a dishwasher; it also sells a brush for washing by hand.

A brown film inside the lower chamber is dried coffee oil. It taints later brews and comes off with a brush and a little detergent.

Faults that come from the design

CoffeeHQ explanation

The brew slows to a drip and will not finish

Usually because: The filter has sealed against the spout, or the grind is too fine for thick paper.

Change first: Put the three-layer side over the spout; if it still stalls, grind coarser.

Pour-over stalling

A papery taste

Usually because: There is a lot of paper, and it has not been rinsed.

Change first: Rinse the filter thoroughly with hot water and pour that water away before adding coffee.

Coffee is lukewarm by the second cup

Usually because: Thin glass loses heat, and a slow brew gives it time to.

Change first: Preheat the vessel with the rinse water and pour into warmed cups.

Who gets the most from it

CoffeeHQ explanation

It suits someone who brews two or more cups at a time, likes a clear, tea-like cup and enjoys the ritual. It is a poor match if you want body and weight in the mouth, since the thick paper removes exactly that, or if you brew one small cup at a time.

It also needs the same supporting kit as any pour-over: a grinder, a scale and ideally a pouring kettle. And it ties you to one kind of filter, which costs more per brew than ordinary papers. That is the price of the cup it makes.

What to do next

• How to brew with a Chemex — Grind, ratio and pouring for the thick filter.
• Pour-over dripper vs Chemex — What the thicker paper changes compared with an ordinary cone.
• How brewing methods change the taste — See thick-paper brewing set against other methods, with the reasons.
• Become a barista — A structured programme from dose and grind through milk, drinks and maintenance.