How sleeping bags are made
In a good down bag, each chamber is filled to the gram, then the fill hole is sewn shut by hand.
- stations
- 6
- things upstream
- 47
- raw sources
- 17
- steps from the ground
- 9
The short version
Down sleeping bags are a quilt of fabric chambers called baffles that keep the down from sliding to your feet. Makers treat the down to repel water, cut and sew the shell, liner and mesh baffle walls, fit the zipper, then blow a weighed charge of down into each chamber through a tube and stitch every opening closed.
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Treat the down
Duck or goose down, mostly a byproduct of birds raised for meat, gets a water-repellent finish before it reaches the sewing floor. Soaked down can insulate worse than no bag at all.
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Cut shell and liner
Light synthetic fabric is cut into the outer shell and inner lining, plus strips of mesh for the internal walls.
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Sew the baffle walls
Mesh walls are stitched between shell and liner to make box-shaped chambers, often offset so each one is a trapezoid. Cheaper and lighter bags sew shell straight to liner, which leaves cold lines at the seams.
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Fit the zipper
A long zipper runs down one side. Mummy-shaped bags usually stop it short of the feet, since every zipper leaks heat.
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Blow in the down
Compressed air pushes down through a metal tube into a small opening left in each chamber. Computer controls release a weighed charge per chamber, with more around the torso and feet than elsewhere.
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Close the fill holes
A skilled machinist stitches every insertion hole shut by hand on a sewing machine.
Goes in
Worth repeating
- Fill power is measured by dropping a small weight onto an ounce of down in a graduated cylinder and reading how high the fluff holds it.
- Eiderdown has the highest fill power of any down, at 1200.
- Rab's old filling stations needed three people each, and one operator on the new computerized line fills more bags than they could.
Back to the ground
Follow every input upstream and sleeping bag starts as these 17 raw sources.
Everything it is made of See it on the map
Open the whole family tree
Keep walking
Sources
- Sleeping bag
- How Do We Build a Sleeping Bag?
- Why Does Rab Still Fill Its Down Sleeping Bags in the UK?
- Baffled By Baffles? Understanding Sleeping Bag Baffles
- Down feather
Cite this page: "How sleeping bags are made." Assembly Line, 2026-11-03. https://assemblyline.org/make/sleeping-bag