Hollowfiber, wadding or silicone fibre: which to choose

A jacket, duvet, pillow or toy needs a filling, and shops offer hollowfiber, sintepon (bonded wadding) and «silicone». All three are synthetic and made of polyester, but they behave differently: one keeps its shape for years, another flattens in a season. Here is how they differ, why, and what to use for what.

Left: fluffy balls of crimped hollow fibre (hollowfiber, siliconised fibre). Right: sintepon, layers of fibre bonded with glue or heat.

Why the same polyester behaves differently

All three fillings are made of polyester, but their properties come not from the material itself but from the shape of the fibre and the way the fibres are joined. Warmth is held not by the fibre but by the air between fibres: the more still air a filling holds in a given volume, the warmer it is. Springiness depends on whether a fibre can return to its shape after compression. And resistance to washing depends on whether the fibres hold together without glue, which breaks down over time.

• Straight solid fibre packs tightly, holds little air and does not spring back by itself after compression.
• Hollow crimped fibre holds air both inside itself and between the coils, and the spiral works like a spring.
• A silicone coating makes fibres slippery: they do not catch on each other and do not clump.

Sintepon (bonded wadding)

The oldest and cheapest of the three. The fibres are glued or heat-bonded into a sheet, so it is sold in rolls of a set thickness. It holds its shape well inside a garment and is easy to cut. The downsides: heavier than hollowfiber for the same warmth, it flattens over time, and glued wadding takes washing less well.

Why it flattens. The fibres in sintepon are mostly straight and solid, and the sheet holds together thanks to glue or heat bonding. Under weight and after washing the bonds gradually break, the fibres pack down, there is less air, and the item loses both volume and warmth. Thermally bonded wadding, where fibres are fused without glue, lasts longer than glued, but does not have the spring of hollowfiber.

Use for: budget outerwear, linings, bags where an even layer is needed.

Hollowfiber

The fibres are hollow and crimped into a spiral, so they hold a lot of air: the filling is light, warm and springy and recovers quickly after compression. It does not absorb moisture or odours, takes machine washing and is hypoallergenic. It comes as sheets and as loose fibre or balls.

Why it keeps its shape. The spiral of the fibre straightens by itself after compression, without glue or extra bonds, so hollowfiber recovers its volume even after many washes. The hollow inside the fibre adds warmth without adding weight.

Use for: jackets and puffers, duvets, pillows, toys, baby sleeping bags.

«Silicone»

This is the everyday name for siliconised polyester fibre: fibre coated with a thin layer of silicone. The coating makes it slippery and soft, the fibres do not catch on each other, and the filling does not clump. It is often sold as balls. Its properties are close to hollowfiber, and it is usually more expensive.

Why it is so soft. Balls of siliconised fibre roll against each other, so a pillow easily takes the shape of the head and just as easily recovers. Hollowfiber treated with silicone gets the same slipperiness, so in shops the line between «silicone» and hollowfiber is often blurred: look at the fibre description, not only the name.

Use for: pillows, duvets, soft toys where softness and even filling matter.

Comparison

What about natural fillings

Down, feathers, wool and cotton are popular too, and each has its strengths: down is very warm and light, wool manages moisture well. But natural fillings absorb moisture, dry slowly, need gentle washing or dry cleaning and can cause allergies. Synthetic fillings are chosen exactly when an item must be washed often, when someone in the family has allergies, or when an affordable price matters.

What to choose

• Clothing: hollowfiber sheet, for a light and warm jacket.
• Pillows, toys: hollowfiber or «silicone» as loose fibre or balls: they make it easy to fill evenly. To refresh an old pillow, see our separate article.
• A budget even layer: sintepon.

How to tell them apart by touch

• Sintepon is dense and even, like felt; stretched, it tears in layers.
• Hollowfiber is fluffy and springy; a squeezed handful springs back at once.
• «Silicone» feels slippery and soft; the balls roll easily between the fingers.

If you buy filling by weight online, look at a close-up photo of the fibre or ask the seller for one: the picture shows straight away whether it is a sheet, loose fibre or balls.

Caring for each

Items with hollowfiber and «silicone» take machine washing at 30-40 °C on a gentle cycle; dry them laid flat and shake them a few times. Sintepon is best washed gently without a hard spin: glued sheets delaminate. No synthetic filling likes drying on a radiator: heat makes the fibre lose its spring.

How long each lasts

Sintepon in pillows and duvets visibly settles within one or two seasons of active use; in garments it lasts longer because it is not pressed constantly. Hollowfiber and «silicone» keep their volume for several years, and when a pillow does sag, the filling can be fluffed or topped up with fresh. Lifespan also depends on care: regular fluffing, drying at room temperature and washing without a hard spin extend the life of any synthetic filling.

Frequently asked questions

Why has my sintepon pillow gone flat and what can I do?

Sintepon fibres pack down over time, and their volume cannot be restored. The simplest fix is to open the case and replace the filling with hollowfiber: we explain how in «How to refresh an old pillow».

Can I wash a hollowfiber duvet at home?

Yes, if it fits in the drum and your machine takes that weight. Choose a delicate cycle, 30-40 °C and a soft spin, and dry it laid flat on a horizontal surface.

Can I mix fillings in one pillow?

You can, but they settle differently, and the pillow becomes uneven over time. Better to fill it with one material.

Which is warmer: sintepon or hollowfiber?

At the same weight, hollowfiber is warmer: it holds more air and keeps its volume longer.

What are «balls» in a filling?

Fibre rolled into small fluffy balls. This way the filling spreads more evenly in an item and clumps less.

Where to buy

We sell hollowfiber in 0.5 kg portions in the Fillers section. How much you need for a pillow, duvet or toy is worked out in «How much hollowfiber you need».