Under the cover

Materials & technology

No mystery fabrics, no invented trademarked layers. This page lists what is in our products, in the words our suppliers use, with the numbers that matter.

Open-cell memory foam

All Onmin mattresses use open-cell viscoelastic foam. "Open-cell" means the bubbles inside the foam are connected rather than sealed, so air moves through the material instead of being trapped against your body. That is the difference between the memory foam of the 1990s — which slept hot — and the material we use today.

Density matters more than marketing names. Our cores run at 35–40 kg/m³ and the comfort layers at 55 kg/m³: dense enough to hold their shape for a decade, soft enough at the surface to let a shoulder sink. Anything firmer than about 65 kg/m³ in a comfort layer tends to feel like sleeping on a yoga block; anything softer than 30 in a core starts to sag inside three years.

The Cloudform's seven zones are cut, not glued: one block of foam profiled with different channel depths from head to thigh, so the zones cannot separate over time.

The gel layer in the Deeprest

Gel-infused foam is ordinary viscoelastic foam mixed with phase-change gel beads. The beads absorb heat while you fall asleep and release it slowly through the night, taking the edge off the first-hour warmth that foam is known for. It does not refrigerate anything — if a mattress claims to be "cooling", the honest translation is "less warm" — but our testers consistently rate the Deeprest surface one to two degrees cooler than the Cloudform under the same duvet.

Pocket springs

Each spring in the Deeprest is individually wrapped in a fabric pocket, so it compresses on its own instead of dragging its neighbours down with it. Two people of different weights can share a king without rolling toward the middle. Our springs are tempered twice — once when drawn, once after coiling — which is the boring detail that stops them losing height in year six.

Covers and fibres

The Cloudform cover is knitted from eucalyptus-derived lyocell fibre with a polyester stabiliser, chosen because it moves moisture away from the sleeper and feels cool under a bare arm. The Featherline's quilted cover uses the same fibre in a simpler weave. Both meet the UK flammability requirements for domestic sleep products, and we publish the test certificates to anyone who asks — [email protected] gets you the PDFs.

The Wingback, materially speaking

The chair's back is a tensioned elastomeric mesh — the same family of material used in high-end task seating — chosen because it gives support without a foam pad to compress and crack. The frame is glass-filled nylon at the stress points and recycled aluminium in the base. The arm pads are a soft polyurethane that survives being leaned on for years; the castors are soft-floor as standard, with carpet castors in the box.

Spare parts stay available for at least seven years after a product is discontinued: covers, castors, gas lifts and lumbar pads can all be replaced at cost by post. A chair that can be repaired is a chair that doesn't need replacing.