Down & Feather Terminology

Baffle Box Construction

In a baffle box construction, the product has boxes sewn into it, but the boxes have vertical strips of fabric sewn to the top and bottom fabrics, creating baffled walls between each box. The baffles allow down to move into the boxes initially, but help prevent the down from shifting from the boxes later.


Down is the soft undercoating of waterfowl, which is comprised of individual down fibers that are connected to one another at a central point.

Down Cluster

A group of components including down, nestling down and plumules.

Fill Power

Fill power is a measure of loft, or the insulation ability of down products in cubic inches per ounce. The higher the number, the more fill power there is.


Down products are often described as having "loft" which, essentially, refers to the fluffiness of the product. The three dimensional nature of the down itself is what gives it loft. When a down comforter or pillow becomes flattened with use, its loft can be easily restored with plumping or shaking.

Nestling Down

Underdeveloped down made up of soft fluffy barbs radiating from a sheath is called nestling down. Nestling Down does not have quills.

Oxygen Number

Oxygen number indicates product cleanliness. Down and feathers are soaked and agitated in a solution of pure water, which is then measured for organic material. The lower the number the better; the cleanest samples measure 1.6-3.2, and the highest number allowed is 10.


Plumage consisting of soft quills and barbs.

Sewn-Through Construction

The top and bottom fabric of the product are stitched together, helping to prevent the down from shifting. A product with sewn-through construction may have boxes, channels or other patterns. While all sewn-though constructions help prevent the down from shifting, a multiple-box construction generally will prevent more shifting than an end-to-end channel construction.

Species Identification

Feathers and down are tested to determine what species of birds they come from.

Thread Count

The thread count is the number of threads per square inch of fabric, measured at least five times and then the results are averaged together. Two-ply yarns are counted as one thread and may not be used to double thread count. Generally, the higher the thread count is, the more down-proof the fabric.


Turbidity helps determine if dust or dirt (organic and inorganic) is present in the down and feather. A sample of down or feathers is soaked and agitated in pure water, then the water is measured for clarity. U.S. and European standards require a result of at least 300 mm. Very clean samples register at 550 mm or higher.

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