Once you have chosen the shape and size of sofa that you want and the constructed frame has the relevant supporting mechanism in place, of either springs or webbing, etc, then the last factor that is going to affect your seating comfort is the type of filling material that is used in the cushions.
The use of foam has always been a popular choice of filing because of its ability to spring back into its original shape when you get up, returning the shape of the cushions back to their designed appearance. Not all foams are the same though, despite all foams feeling fairly firm when you first sit on them, the foams vary in their density which allows manufacturers to offer a range of comforts from very firm (very dense) to soft.
Restrictions came in during the 1980s, to control the type of foam that could be used in sofa padding and other furniture, requiring the properties of the foam to be more fire resistant. In the UK the ‘Furniture and Furnishings Fire Safety Regulations Act of 1988’ was introduced after a series of fatal home fires involving furniture. Today sofas are required to carry a label from the manufacturer stating that the foam used meets this legislation but beware, some cheap imports which aren’t properly fire retardant are being falsely labelled and sold in open air markets and via other methods. The safest place to buy a foam filled sofa is from a reputable furniture store.
An alternative filling for cushions is the use of specially developed polyester fibre. These types of cushions will never be as firm as a dense foam cushion but can have their firmness varied between medium to soft by controlling the levels of filling put into them. They don’t spring back into shape when you get up and therefore need to be ‘plumed up’ on a regular basis to give the sofa a neat appearance.
As with any pillow or cushion you can of course use a traditional filling of feathers. Seen as the luxury filling by most people, they are again going to be a softer cushion to sit on than foam and like the polyester fibre they don’t maintain their shape, so daily reshaping is necessary. To avoid the feather filling from working its way through the cushion fabric, the filling is contained within a bag inside the cushion cover, as is the fibre filling type usually.
Finally here are some simple tips to help maintain the appearance of your sofa and thereby make it last longer:
If the style of sofa permits, go for loose covers that can be washed; failing that get removable cushion covers that are washable and use arm covers and ‘antimacassars’ to protect the high contact points of grime from the hands and head (greasy hair). Pick a ‘moveable’ sofa that allows you to move it around the room so that you can vacuum the area easily and so that you can locate the sofa in different positions, thus changing the appearance of the room from summer to winter for example and if the room is carpeted, it also relieves wear points on the carpet from both the feet / casters of the sofa and from where peoples’ feet wear the carpet just in front of the sitting area.
Go for the best quality sofa you can afford at the time and consider having it stain protected from new, especially if you have occupants who are likely to spill things; keep the base colour simple and neutral and then add brighter colours and patterns to the sofa via colourful scatter cushions. If your colour scheme in the room changes it is much easier and cheaper to change scatter cushions than it is to replace the sofa or its covers. If the cushion support mechanism fails but the upholstery is still in good condition, you can consider several systems that rejuvenate the support areas and will extend the useable life of the sofa.