A cover is the part you choose with your eyes. The insert is the part that decides whether the cushion still looks good in two years. People spend an hour on the first and thirty seconds on the second, so here is the thirty seconds done properly.

Feather

Feather is what gives a cushion the soft collapse you get in a good hotel. Each feather compresses under you and springs back when you stand, which is why a feather cushion still has loft years in. The trade is maintenance: it wants a shake and a plump every few days, or it sits flat and apologetic in the corner of the sofa.

It costs more at the start and less over time, because it does not need replacing. The exception is anyone in the house with a feather or dust mite allergy, where it is simply not worth the argument.

Polyester

Polyester holds a shape without being asked. On a cushion that is mostly decorative, sitting against a bedhead or at the end of a sofa nobody leans on, that steadiness is exactly what you want. It is lighter, it washes without ceremony, and it is the kinder choice for allergies.

What it will not do is recover forever. Fibres crush under daily use and eventually stay crushed, so a hard working polyester cushion has a life rather than a lifetime.

The short answer

  • Sofa you actually sit on: feather, and accept the plumping.
  • Bed dressing, or a room used lightly: polyester.
  • Allergies in the house: polyester.
  • A piece you want to last decades: feather.

Blends exist and are a reasonable compromise, with enough feather for softness and enough fibre to hold up between plumps.

The rule that matters more than the filling

Whichever you choose, buy the insert about 2 cm larger than the cover. A 45 cm cover wants a 47 cm insert. Match them exactly and the corners stay empty no matter what is inside, and the cushion looks tired while it is still new. We go into sizing properly in what size cushion do you actually need.

What we put in ours

Where a piece comes with an insert, its page says which one. The covers themselves are in the contemporary cushions and lumbar collections, or the full list if you would rather see everything at once. If you are having something made from your own fabric, the insert question comes up at the same time, and that is a custom order.