By Adalheid Voigt. Midcentury. At Wednesday, January 09th 2019, 01:09:07 AM.
Wood can hold a lot of moisture when it is first harvested. What makes a kiln-dried frame better is that the process gets rid of most of the moisture inside the wood. Kilns are huge ovens with very strictly controlled temperatures and humidity. The kiln drying process can remove approximately 93% of the wood's moisture.
The eight-way hand tied springs system is one of the best support systems. The craftsman connects each spring to the adjoining one with a strong twine. The twine passes front to back, side to side and then diagonally in both directions, thus tying each spring securely. Another method is sinuous spring construction. Sinuous springs are “S”-shaped and run from the front of the seat to the back. These springs are supported by additional wires that cross from side to side. This also makes for a strong seat, and it might be the preferred option in a sleeker style or smaller frame because it requires less space.
There are alternatives to kiln-dried hardwood frames. Metal sofa frames are available, too, but metal can be prone to oxidation along with seasonal changes. Changes in humidity can affect metal frames, so look for one that has been treated to protect against atmospheric changes. Plywood frames as long as they are thick enough can also work well. As a matter of fact, many leading manufacturers now use well-constructed plywood frames.