What Is Coffee Chaff? (And Where Does It Go During Roasting?)

If you grind your own beans at home, you’ve probably noticed those pale, papery flakes mixed in with your ground coffee or tucked inside the center seam of the beans.

In the industry, we call it chaff.

While it might look like random dust that doesn’t belong in your bag, it’s actually a completely natural part of how coffee grows and roasts in our drum.

Here is what chaff actually is, where it fits into the stages of roasting, and why it's nothing to worry about.

What Actually Is Chaff?

To understand chaff, picture a coffee cherry on the tree. Deep inside the fruit, wrapped around the green coffee seed, sits a razor-thin protective layer called the silverskin (or epidermis).

When green coffee beans arrive at our, that thin silverskin is still tightly bound to the raw seed.

To get rid of it, the beans have to go through the heat of the roaster.

Where Chaff Fits Into the 5 Stages of Roasting

In the roaster, every batch moves through precise stages. Chaff makes its big appearance right at the pivot point between drying and browning:

Drying: Raw green coffee enters the drum containing 7 to 11 per cent moisture. Before any browning can happen, we have to drive that water out using heavy heat energy.

Yellowing & Chaff Release: As the water evaporates, the beans turn yellow and expand. The dry silverskin cracks open and flakes off as chaff. Air flowing through the drum pulls the floating chaff into a collector to prevent fire risk inside the roaster. (Proper drying here is critical: if beans aren't dried evenly, the core stays undercooked, resulting in a cup with unpleasant outer bitterness and inner grassy sourness.)

First Crack: Pressure from carbon dioxide and steam builds inside the bean until it pops open with a distinct snapping sound, nearly doubling in volume. This is where signature coffee flavours rapidly develop.

Roast Development: The surface of the bean smooths out. Here we balance acidity and bitterness, as the roast continues, bright fruit acids degrade while deeper, caramelized tones build up.

Second Crack: A quieter, snappier crack where structural walls break down and oils are pushed to the surface. Pushing past this point burns away the intrinsic characteristics of the origin in favour of dark, smoky roast flavours.

Most chaff is pulled out by our roaster’s airflow during stage 2, but because coffee seeds fold inward along their center seam, a tiny bit of silverskin stays trapped inside that inner fold all the way through the roast.

Why Do Some Bags Have Way More Chaff Than Others?

Ever notice how a bright, fruit-forward African coffee has more visible flakes than a dark roast?

It comes down to roast depth and bean density:

  • Darker Roasts: Coffees taken into or near Second Crack expand more, sweat oils, and spend more time at high temperatures, which incinerates almost all remaining silverskin.
  • Lighter & High-Altitude Roasts: Coffees grown at high elevations (like a washed Kenya AA Sondhi or Ethiopia) are dense and hard. Because we roast them lighter to preserve their natural acidity and floral character, more silverskin stays tucked inside the seam.

The Takeaway: You Don't Need to Do Anything About It

Chaff is virtually tasteless and paper-thin. In a pour-over or drip brewer, it simply floats to the top during brewing without altering your extraction or flavour.

When you see those pale bits in your coffee, don't sweat it or try to pick it out—it just means you’re drinking dense, high-elevation beans roasted with enough care to keep their natural origin intact.

Got questions about a specific origin or roast profile on our shelves? Drop by the shop in Kensington and ask us while we pour your morning brew!

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