How to Use a Vietnamese Phin Filter

What it is, and what people call it

A phin is the Vietnamese coffee filter, a small metal cup that sits on the rim of a glass and drips coffee down into it. English-language listings rarely use the word: the same object is sold as a Vietnamese coffee filter, a Vietnamese coffee maker, a Vietnamese drip filter and a Vietnamese coffee press.

In Vietnamese the device is a phin, and coffee brewed in one is cà phê phin. The name is generally attributed to the French filtre, though we have not found a lexicographic source for that derivation, so treat it as the common account rather than a settled one. What the word means, how to say it, and why filtre would come out as one syllable are on how to say cà phê sữa đá, and phin.

It is not a French press and it is not a pour-over. A French press steeps and then separates with a plunger; a pour-over asks you to keep pouring in stages. A phin takes one pour, and then you leave it alone for four to six minutes. If you do not have one, Vietnamese coffee without a phin covers what else gets close.

The four parts

Water goes in the top, gravity pulls it through a bed of coffee, and it drips into the glass. The perforated base plate is the filter, so there is nothing to buy and nothing to replace, and the press plate is the only adjustment on the whole device. Which metal, which size and which press to look for are in choosing a phin filter.

The method

Everything below assumes a 120 ml phin: 20 g of coffee, 100 ml of water, four to six minutes. Phins, grinders and roasts all differ, so treat those as starting points. The two sections after the method are how to read what yours is doing.

1. Warm everything

Rinse the chamber and the glass with hot water and tip it out. A phin is a small amount of metal holding a small amount of water, and a cold phin and a cold glass pull a surprising amount of heat out of 100 ml. Warming them first leaves more of that heat in the brew.

2. Dose 20 g, and level it

Twenty grams for a 120 ml phin. That will fill the chamber roughly a third to a half full.

With no scale, use about four level tablespoons rather than the three usually quoted. Even four is approximate, because a spoonful changes weight with grind and roast, so go by the chamber: a third to a half full, whatever the spoon says. How much coffee goes in a phin has the spoon arithmetic, the doses for the larger sizes, and where 1:5 comes from.

Tap the side of the phin to settle the bed flat. Do not tamp it. A phin is a gravity brewer, and a compressed bed will either stall completely or channel — water finding one weak path through and running straight down it, leaving most of the coffee untouched.

3. Set the press so it just touches

Lower the press plate onto the coffee and turn it down until it makes contact. Stop there.

The press plate is not a tamper. It exists to keep the bed level and provide gentle, even resistance, and the coffee does the sealing itself when it swells in the bloom. Screwed down hard, the plate either chokes the brew or forces water round the edges. This is the step that goes wrong most often.

If your phin has a screw-down press, half a turn past contact is plenty. If it has a loose gravity insert, just set it down.

4. Bloom with about 20 ml

Pour just enough water to wet the grounds — about a tablespoon and a half — and wait 30 to 45 seconds.

Carbon dioxide trapped from roasting escapes, which would otherwise push water away from the grounds and give you an uneven extraction. At the same time the bed swells upward against the press plate, and that swelling is the seal that slows the rest of the brew.

Skip the bloom and the drip will run fast and taste thin.

5. Fill, lid on, walk away

Add the remaining 80 ml and put the lid on. The lid keeps the heat in, and a phin that runs cold extracts poorly.

Then leave it alone. Stirring, lifting the lid to look or pushing the plate down to “help” all disturb the bed; phin brew time explains what that does.

6. Read the drip

A good drip is roughly one drop per second at the start, slowing steadily. When it becomes occasional rather than rhythmic, it is done, usually four to six minutes after the main pour.

Lift the phin off and rest it on the upturned lid, which is what the lid’s rim is shaped for.

What coffee to put in it

Any coffee will brew in a phin. Grind is the only thing that has to be right.

Grind medium-coarse. Roughly the texture of coarse sand. An espresso grind will choke the filter and a French-press grind will fall straight through it. Most coffee sold ground in Vietnam is already in this range, because a phin is what the domestic market brews with. See the grind a phin wants for how to judge it by eye.

Robusta is traditional, but optional. The device and the drinks built around it assume dark-roasted robusta (Coffea canephora): the condensed milk in a cà phê sữa đá (Vietnamese iced coffee with condensed milk) needs a coffee heavy enough to come through it. A Vietnamese arabica will brew perfectly well in the same phin and taste like a different drink, which is a reasonable thing to want. Which robusta to buy comes down to three things on the bag.

Read the ingredients on Vietnamese-roasted coffee. Butter, sugar, soybean, corn and “natural flavouring” all turn up in traditional Vietnamese roasting — sometimes deliberately for body and aroma, sometimes as filler at the cheap end. Either way, what is in the glass is not only coffee. Choosing Vietnamese coffee beans goes through what the labels mean.

The three variables, and what each one does

Everything about a phin brew is controlled by grind, dose and press pressure. When something is wrong, the table says which one to move first.

Symptom	Most likely cause	What to change
Finished in under 2 minutes	Grind too coarse	Grind one step finer
Finished in under 2 minutes, grind looks fine	Not enough coffee for the chamber	Add 2–3 g
Finished in under 2 minutes, water round the edges	Bed not level, or press tilted	Level the bed, reseat the press
Took over 8 minutes	Press screwed down too far	Back it off to barely touching
Took over 8 minutes, press already loose	Grind too fine	Grind one step coarser
Never dripped at all	Both of the above	Start over, coarser and looser

Move one of them per brew; the grind guide explains why. The longer version of this table, with the causes in the order worth checking, is on phin brew time.

Water temperature

Just off the boil — roughly 90–96 °C. The range cited as the standard for proper extraction in the drip-brewing literature is 92–96 °C, and boiling water poured straight onto a dark Vietnamese roast can push an already-bitter coffee into acrid territory. Let the kettle stand for thirty seconds.

Temperature matters less than those numbers suggest. A sensory study that brewed the same coffee at 87, 90 and 93 °C, holding brew strength and extraction constant, found no difference a trained panel could reliably taste. Get the temperature roughly right and spend the attention on grind instead.

If you are brewing a lighter roast or a Vietnamese arabica, use water closer to the boil. Lighter roasts are harder to extract and need the heat.

Cleaning

Rinse it after each brew.

Phins are stainless steel or aluminium with no gaskets, so there is nothing to perish. Do not use abrasive scourers on aluminium, because it scratches and then discolours. Every few months, a soak in hot water with a little dishwasher powder will clear any coffee oil that has built up in the perforations, which is worth doing if the drip has slowly got faster over time for no other reason.

What a phin is not good at

A phin is a poor tool for a delicate, high-acidity light-roast arabica. The long contact time, the metal filter and the sediment all push toward body and away from clarity. If you have bought a washed Cầu Đất arabica with tasting notes of jasmine and citrus, a V60 will show you more of it.

What the phin does better than anything else is produce a small volume of very concentrated, heavy-bodied coffee with no equipment, no power and no skill curve. Every Vietnamese coffee drink is built on that.

Ratio, grind, timing and what to do without a phin at all are collected under brewing.