Compressed sofas are judged twice: once in the showroom after the foam has recovered, and again eighteen months later in the customer's living room. The material specification you sign off at sampling determines both outcomes. This guide gives you the four numbers that matter, what to ask your factory for, and how to read the test reports you receive.
Material Specification Sheet
Use this as a request list when you brief a supplier. The acceptable ranges below are typical for mid-to-high volume export programs and should be tuned to your retail price band.
| Parameter | Test basis | Recommended range | Reject if |
|---|---|---|---|
| Seat foam density | ISO 845 / GB/T 6343 | 28–35 kg/m³ (1.75–2.2 lb/ft³) | Below 25 kg/m³ |
| Support factor (65%/25% IFD) | ISO 2439 | 2.0–2.6 | Below 1.8 |
| Compression set, 24 h at 70°C | ISO 1856 | ≤ 5% | Above 8% |
| Fabric abrasion | Martindale, ISO 12947 | 25,000–40,000 cycles | Below 20,000 cycles |
| Fabric pilling | ISO 12945-2 | Grade 4 or better | Grade 3 or below |
| Flame retardancy | CAL TB 117-2013 / BS 5852 | Pass, with test report | No report on file |
Reading Each Number
Foam density: the load-bearing baseline
Density is mass per unit volume, not firmness — a common confusion in buying conversations. Two foams can feel identical in the hand while a 28 kg/m³ grade loses height far faster than a 32 kg/m³ grade under daily seating. For compressed packaging, density is also a compression-limit input: below roughly 25 kg/m³ the cell walls do not reliably survive a 60–70% volume reduction and slow recovery becomes visible to the end customer. Ask for the density of the recovered block, not the pre-compression block, and specify seat and back separately — back cushions at 22–25 kg/m³ are normal and save cost without hurting the experience.
Support factor: where comfort actually comes from
Support factor divides the 65% indentation force by the 25% value. A low ratio means the foam collapses progressively and the frame is felt through the seat; a ratio near 2.2–2.6 keeps the first centimetres soft while resisting bottoming out. This single figure explains most "feels cheap" complaints on compressed ranges, and it can be improved either by raising density or by switching to a high-resilience grade — the second option is usually cheaper per unit of improvement.
Abrasion and pilling: fabric life in real rooms
Martindale cycles tell you how the face of the fabric behaves under rubbing; pilling grade tells you what it looks like after that rubbing. For a family sofa, 25,000 cycles is the practical floor, and anything below 20,000 should be reserved for decorative or occasional pieces. Pilling is the more visible failure: a Grade 3 fabric can shed fibres within weeks and generate returns that cost more than the upgrade to a Grade 4 weave. If you are specifying a bouclé or looped yarn for its texture, insist on the pilling report before approving the hand-feel.
Flame retardancy: documentation, not adjectives
Requirements differ by destination: CAL TB 117-2013 for the United States, BS 5852 for the United Kingdom, and equivalent national standards elsewhere. The specification that matters is not "FR treated" but which standard, which test report, and whether the certificate names the exact foam and fabric combination you are buying. Treatments can also change hand-feel and colour fastness, so retest the recovered sample rather than approving from a swatch card.
Procurement Recommendations
Put density, support factor, compression set, abrasion, pilling and the named flame standard on the purchase order itself, with the test method cited next to each value — verbal specifications do not survive a factory change of foam supplier. Require a 24-hour recovery check on three cartons per container: measure seat height immediately after unpacking and again after 24 hours, and reject the batch if recovery falls short of your agreed tolerance. Finally, keep one retained sample of foam and one metre of fabric per approved colourway in your own office. When a claim arrives two seasons later, that retained sample is the only evidence that settles whether the material changed or the customer's expectation did.
