An innerspring mattress is made with an innerspring core to which a compressed felt and foam is added. There are several types of innersprings but the two most common are Bonnel Springs and individually wrapped pocket coil springs.
The Bonnel Spring is the oldest coil on the market. Developed in the late 1800’s, Bonnel springs were used in the fabrication of seats for horse drawn carriages. The springs made the bumpy carriage ride less painful and it wasn’t long before the coils started to be used in mattress constructions. The bonnel spring is shaped like an hourglass, which is what gives the coil its strength. It’s very important that the steel in a Bonnel spring be tempered at least twice. It’s also important that the spring be not compressed for transport. (Imported springs are compressed in order to fit more in a container: a 6” Bonnel spring is usually compressed to 1 ½” before being shipped.) A compressed spring will loose about 30% of its strength.
Features of a Bonnel Spring
- The all steel construction makes the Bonnel very durable and long lasting.
- The Bonnel Spring is perfect for very hard and stiff mattresses.
- Bonnel springs allow air to pass freely within the mattress thereby generating less heat.