Ask a shop for coffee "ground fine for filter" and there's a good chance you'll get espresso grind. It's an easy mistake, and it'll make bad coffee every morning until you spot it.
In short: a South Indian filter needs a grind like fine rava, about 400 to 600 microns: distinct grains with a little powder. Espresso grind is too fine and stalls the filter. Pour-over grind is too coarse and runs through thin. The decoction should finish in 12 to 15 minutes.
Why this brewer needs its own grind
An espresso machine uses pressure and 28 seconds, so it can take a very fine grind.
A pour-over uses gravity over three minutes and needs a medium grind.
A French press just soaks, so it takes a coarse grind and four minutes.
A South Indian filter has no pressure and lots of time. Water seeps through for 10 to 20 minutes, so the grind has to be fine enough to give up its flavour to a slow trickle, and coarse enough not to seal the bed shut.
What the right filter coffee grind size feels like
Rub a pinch between finger and thumb:
You should feel distinct grains with a light dusting of powder.
Not flour or talc. That's espresso.
Not coarse sand or sugar crystals. That's pour-over.
Or tip a spoonful onto a white plate and tilt it. Filter grind slides in a loose heap. Espresso clumps and sticks. Pour-over scatters into single grains.
Grind
Roughly
Espresso
200 to 300 microns
South Indian filter
400 to 600 microns
Pour-over
600 to 800 microns
French press
About 1,000 microns
Why espresso grind fails
Espresso grind has lots of dust-sized particles. Under pressure that's fine. Under gravity, the dust sinks into the gaps and packs the bed tight. Flow slows, then stops, while the coffee sits in water for 25 minutes instead of 12.
You get a harsh decoction and half the volume you expected. Most people then add more coffee, which packs it tighter still.
If your filter regularly takes more than 20 minutes, the grind is too fine. Not your technique, not your filter.
Why too coarse fails
Pour-over or French press grind leaves big gaps, so water runs straight through in three or four minutes. The decoction comes out pale, thin and sour, with an odd bitter finish. Add milk and you get coffee-flavoured milk.
The giveaway: done in under five minutes and see-through in the glass.
Buying it right
Buying ground? Ask for the South Indian Filter grind by name. "Fine" usually means espresso. "Filter" in specialty shops usually means pour-over, which is where most of the confusion comes from.
Of ours, only Velvet Mocha comes in the South Indian Filter grind. The rest come as whole beans or as Powder, an all-round medium grind that's coarser than a filter wants. For a dabara, buy those as whole beans and grind them at home.
Grinding at home? Use a burr grinder. A blade grinder makes dust and boulders in the same spoonful, and in a 20-minute brew you taste both. On 1Zpresso and Timemore hand grinders, start around 40 to 55 clicks from zero. On a Hario Skerton, about two-thirds of the way from fine to medium. Then adjust by the clock.
Buy small. Filter grind stales faster than coarser grinds. Buy what you'll finish in two to three weeks. Here's why the bulk buy doesn't save money: roast date vs expiry date.
Dial it in over three mornings
Morning one. Brew as usual. Time the drip and taste the decoction before adding milk.
Morning two. Under 8 minutes and thin? Go one or two clicks finer. Over 20 minutes or stalled? Go two or three clicks coarser. 12 to 15 minutes and tasty? You're done.
Morning three. Confirm it. Change one thing at a time.
Water temperature, dose and milk ratio are worth tuning once the grind is right, and rarely before.
What to brew in it
Velvet Mocha is the one we built for the dabara, with dark chocolate and a gentle sweetness that survives milk. It's only sold in the South Indian Filter grind, because it doesn't make sense any other way.
For more sweetness and less weight, Toasted Almond and Cookie Bandit both work beautifully in a filter. Buy them as whole beans and grind to fine rava.
