In China, a foam density of around 50 is considered good, as anything over 50 likely contains additives that you might not want in your foam.
However, a higher density doesn’t always mean better quality for sofa cushions. For seat cushions, a density exceeding 35 is generally sufficient. The key factor is actually the combination of different foam densities.
Common foam types are categorized into high-density foam, medium-density foam, and low-density foam based on their structure. According to the interpretation of the Chinese customs department, foam with a density of ≥45 is considered high-density, foam with a density between 45 and 18 is medium-density, and foam with a density <18 is low-density.
In general, higher density foam is firmer, although it’s possible for some high-density foams to have super-soft additives, making them very soft and suitable for use in sound-absorbing materials, sofa cushions, and upholstery. Even within the same density range, foam can vary in terms of softness and firmness. Medium-density and low-density foams are typically used for general protective applications, while high-density foams are often used for sound absorption, sofa cushions, and upholstery materials.
For sofa seat cushions, a density of around 35 is commonly used, with variations available in terms of softness, firmness, and super-soft options. Mattresses typically use a density of around 22. The term “high-density foam” is a common marketing term used by salespeople. High-density foam has many small cells and is very full, but it is generally not suitable for absorbing water.
For furniture applications, such as fabric sofas and high-resilience foam:
- Seat cushion density should be above 30 kg/cubic meter.
- Back cushion density should be above 25 kg/cubic meter.
- In most cases, the ideal seat cushion should indent by around 10 centimeters when a person sits down.
- Rebound rate should be above 60%.
To improve comfort when sitting or lying down, foam can be softened without reducing its density. Some sofas incorporate vertical coil springs in the seat cushions to provide higher resilience and durability.
