The comfort and lifespan of a sofa are decided long before the fabric is chosen — they are decided by what is inside. Foam grade, filling blend, and fire treatment determine how a seat feels on day one and whether it still feels right in year three. For importers, specifying the filling is not micromanaging; it is the difference between a product that earns repeat orders and one that comes back as a complaint. This guide covers what to put in the spec.
1. Foam density: the durability number
Density is measured in kilograms per cubic metre (kg/m³). It is the single best predictor of how long foam resists collapse. Commodity foam around 20–25 kg/m³ is cheap but softens quickly in high-use seats. Mid-grade 30 kg/m³ is the workhorse for residential sofas. High-resilience (HR) foam at 35+ kg/m³ holds its shape under daily contract or family use. When a quote says only ‘standard foam’ without a density, that is the line to push on.
2. ILD: the firmness number
Indentation Load Deflection (ILD, sometimes IFD) measures how much force it takes to compress the foam 25%. Roughly, 25–30 ILD reads as soft, 30–40 as medium, 40+ as firm. ILD and density are independent: a high-density foam can still be soft if its ILD is low. A sensible residential seat sits around 32–36 ILD over a 30+ kg/m³ base — supportive without feeling like a bench.
3. Seat versus back: different jobs
The seat takes the load, so it gets the higher-density, medium-ILD foam. The back can be softer or use a fibre/foam composite because it is not load-bearing in the same way. Specifying the same foam everywhere either wastes money (over-spec’d back) or risks early failure (under-spec’d seat). Vashone typically quotes seat and back foam separately for exactly this reason.
4. Down and fibre blends
A down/fibre wrap over a foam core gives the relaxed, sink-in look buyers associate with premium pieces. The trade-off is maintenance: blends shift and need plumping, and pure down is costly and buoyancy-variable. A common spec is a foam core with a 20–30% down/fibre topper — the look without the full cost or the full fuss. For contract or care-home projects, a fibre-only wrap is often the safer call.
5. Fire compliance varies by market
This is where filling spec meets law. For the US, CAL 117 is the baseline smoulder standard for residential upholstery. For the UK and EU, EN 1021 covers cigarette and match resistance, and the UK adds the Furniture and Furnishings (Fire Safety) Regulations with composite (crib 5) requirements for certain settings. Specifying ‘fire-resistant’ is not enough — name the market and the standard, because the treatment and the paperwork differ.
6. What Vashone puts in the BOM
On a custom programme, Vashone records foam density and ILD per component, the filling blend ratio, and the fire standard by destination market — all in the bill of materials tied to your approved sample. That way the production run matches the sample, and a buyer in California and a buyer in London get foam treated to their own rulebook.
7. Practical takeaways for importers
Ask for density and ILD, not just ‘high quality foam’. Separate seat from back. Choose a down blend only if the product story supports the upkeep. And state the fire standard by country — it changes both the chemistry and the certificate that ships with the container. Specify the inside, and the outside takes care of itself.
Good filling is invisible when it works and impossible to ignore when it fails. Put it in the spec, approve it on the sample, and the sofa will feel right long after the photoshoot.