Illums Bolighus' guide


Do you know how to wash your duvet? Why do we talk about a duvet’s insulation and absorbency? What is fill power exactly? Find the answers below.

Duvets & pillows

Insulation & absorbency

Down are one of the best insulation materials, as they can obtain and absorb moisture. A down consists of a microscopic core from where thousands of small soft rays are attached. Small air pockets are created between the rays, wherein air stand still and thus insulate.


Often pillows have a mixture of down and feathers. Feathers are part of the filling to give your head support.


A duvet is filled with down to create insulation which in return holds on to your body’s heat.

Fill power

Ringsted Dun explains, ”fill power is an expression of the insulating properties of the down, and thus their quality. A high fill power means that the filling is light, airy and insulates well”. The air between the down, and not down itself, is what makes a duvet warm. In other words, with a high fill power, you need less down for an optimal insulation. Her are 2 other tips:

- Higher down percentage = higher fill power

- Better down quality = higher fill power

In practice

The fill power number is a technical expression for how many centimetres filling is needed to press up a stamp in a cylinder container. Thus, fill power explains down’s ability to rise after pressure.

Care instructions

- Down products can be washed at 60° C – house dust mites die at around 55° C

- However, we recommend tumble drying your duvet or pillow at high heat, as it is more gentle on the dow

- If you want to wash your duvet or pillow, you need to use an enzyme-free detergent i.e. wool wash

- We recommend tumble drying your duvet every second month and your pillow every month

- We recommend changing your duvet every 5-7 years and your pillow every 2 years



Are you looking for a featherless duvet or pillow? Fossflakes’ filling is invented by entrepreneur and civil engineer Lars E. Foss. One day, during a film production he saw how employees were taking naps on bags with artificial snow, and so he developed the filling which is composed of 100% extended polyethylene polymers.

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