Martin Jungfer
Product test

Sembella Geltex: mattress foam still can’t match a good old pillow

Martin Jungfer
19.7.2024
Translation: Patrik Stainbrook

Sembella’s Geltex pillow comes in a unique shape. For side sleepers in particular, it’s apparently the perfect companion. But is this true? I’ll figure it out in a test.

A good pillow is essential to healthy sleep. Plenty of people go through a bunch before finding the right one for them. As a result, manufacturers come up with ever-new ideas – like this Geltex pillow, which I’ve been testing over the past few weeks.

I start by looking at Sembella’s product description. Here’s each point:

A specially shaped pillow

Well, that’s obvious. The dimensions of the Sembella pillow don’t fit any of the current standards. It’s 68 centimetres long, 34 centimetres wide and around eleven centimetres tall. It won’t work with any common pillow cases.

The shape should serve your needs if you sleep on your side.
The shape should serve your needs if you sleep on your side.
Source: Martin Jungfer

A 100 per cent GELTEX® core

Remember: it’s always best to use capital letters in marketing. They make a word stand out from the uniformity of text. NOPE. Even with a trademark symbol behind it, Geltex isn’t any better or more important than anything else. After all, it’s nothing more than a specific polyurethane foam, combining the properties of open-cell cold foam and elastic gel. And while the «100 per cent» could suggest purity, it actually only means that the core is made from this one material. Lowering production costs. These marketing drones are pretty clever…

Ventilation channels for pleasant sleep

Ooh, now we’re getting fancy. You could also simply call these «ventilation channels» what they are: holes cut into the foam block. They ensure that the centre of the pillow is slightly softer, so your head sinks in more there. However, ventilation is physically restricted since your head is at one end of the tunnel and the other end is on the mattress. More like congested ventilation, then. In any case, I didn’t feel any cooler than with a pillow without ventilation. Even Swiss cheese probably has better aeration than this pillow. Stronger smell, though.

Photographed against light, the holes, i.e. «ventilation channels», become visible.
Photographed against light, the holes, i.e. «ventilation channels», become visible.
Source: Martin Jungfer

A washable cover

Thank goodness, for once they’re not being obtuse. I can remove the cover of the Geltex pillow and wash it at up to 60 degrees. Pretty important too, since I only have this one cover. I can’t fit anything else on because of the special shape (read above section). When attaching the cover, I notice I can only use it on one side. There’s a zipper on the back. Lying on it would prove pretty uncomfortable. But I don’t think the intended side is ideal either. The cover has a clearly perceptible structure to it. Even the word Geltex (in capitals, of course) is emblazoned. It’s very possible the brand name could imprint on my cheek overnight if I position my head the wrong way. No thank you.

There’s a thin layer of cellulose between the Geltex core and the cover. It’s pretty low-quality, there’s already loose thread on either side.

There’s a thinner cover underneath the actual pillowcase, which mainly wraps around the foam.
There’s a thinner cover underneath the actual pillowcase, which mainly wraps around the foam.
Source: Martin Jungfer

How did I sleep on the Geltex pillow?

The shape of this Sembella Geltex pillow kind of reminds me of a bone-shaped dog treat: narrow in the centre, wider at the ends. Here’s why they did this: as a side sleeper, my head lies in the middle, while the wider sides support my neck and shoulders. Broadly, this works quite well for me. However, I find the centre section of the pillow too soft; the ventilation tubes in the foam noticeably reduce stability here.

The pillow has two heights, eight centimetres on one side and 11.5 centimetres on the other. However, height alone says little about whether you’ll be comfortable lying on it. Material strength is another important factor here. And compared to other pillows, Sembella’s Geltex foam tends to be on the softer side and offers little support.

My kettlebell serves as a prop head. Four kilograms of weight clearly compresses the pillow. The pillow even lifts slightly at the side.
My kettlebell serves as a prop head. Four kilograms of weight clearly compresses the pillow. The pillow even lifts slightly at the side.
Source: Martin Jungfer

This could also be due to the fact that Geltex was originally a foam developed for mattresses and toppers. It’s found, for example, in mattresses from Schlaraffia. Until recently, like Sembella, it belonged to the Belgian Recticel Group, whose polyurethane foams are used for insulation, noise protection and bedding, among other things. Schlaraffia and Sembella have been part of the Portuguese Aquinos Group since 2022.

However, pillows have slightly different requirements than a mattress. From a business point of view, putting foam you already produce into a pillowcase and selling it may sound convincing.

But I’m not convinced. Even the higher side is too low for me. The pillow cover is too rough in my opinion, and the Geltex lettering on it is completely unnecessary.

The cover is highly textured. You might even have marks on your face when you wake up.
The cover is highly textured. You might even have marks on your face when you wake up.
Source: Martin Jungfer

In a nutshell

A pricey chunk of foam

Sembella’s Geltex pillow is priced at over 150 francs/euros – too much for what’s essentially just a piece of foam. It looks ergonomic, but doesn’t actually stand up to scrutiny here. It’s too soft and doesn’t offer enough support. On top of that, it’s included pillowcase is questionable at best.

Pro

  • pillowcase machine-washable at 60 degrees
  • ventilation holes in the foam core
  • variable heights with a simple turn

Contra

  • highly textured pillow cover leaves imprints on face
  • shoddy slip cover
  • foam very soft, lacking support
  • weird dimensions prevent using a different pillow case
Sembella Geltex Premium (34 x 68 x 11.5 cm)
Pillows

Sembella Geltex Premium

34 x 68 x 11.5 cm

Header image: Martin Jungfer

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