Upholstery considerations and coil springs
Why bother with coil springs?
The upholstery, from the beautiful outer fabric covering, down through the padding, springs, burlap webbing, and the box which holds them, must be decided upon when designing the piece of furniture. Beyond aesthetics, in chairs and couches in particular, the upholstery plays a significant role in how comfortable the furniture will be. Is the seat spongy, too hard, or just right? Do I want to sink luxuriously into a seat or rest lightly on top of it? How will I feel after sitting for two hours and reading a book?
Secondly, but no less importantly, the upholstery is important to the longevity of the piece of custom furniture. In recent years, even supposedly "high end" or "handmade" custom furniture has been constructed with long wire-like zig-zag springs. These types of springs place tremendous strain upon the furniture's frame and will eventually tear the chair or sofa to pieces. They are increasingly used because they are inexpensive and can be installed cheaply and easily by the unskilled.
Traditionally "coil" springs (see below) were used. You may remember having seen these coil spring sticking up out of very old mattresses and chairs. In these instances, that coil spring suspension system had actually outlived the fabric covering and sometimes even the frame of the chair itself! In contrast to zig-zag springs, coil springs literally last forever and impart a comfort to a seat that cannot be matched by other means. However, there has never been a machine that could choose, arrange, and then intricately hand-tie these springs in place. It is time consuming and must be done with an accuracy that demands skill and patience.
Pictured below is the seatbox of the quartersawn oak rocking chair shown at left. The coil springs are tied with a four-way tie instead of a more rigid and common eight-way hand tie because the chair is intended for a lightly built woman. Remember the story of the three bears? All of the chairs were built differently. For example. a heavier or larger person will not feel comfortable in a chair built for a child. One more advantage of custom craftsmanship.
The poplar "box" and a burlap base
1. First a "box" is made out of Poplar wood. This wood is traditionally chosen because of its lightness, strength, and ability to hold upholstery nails and tacks. Strong burlap webbing is then woven and stretched across the bottom of this box to form a bed for the coil springs.
Clincher tool for attaching the coil springs to the burlap
2. The appropriate size and strength coil springs are chosen and arranged on the burlap webbing. The selection of the springs and this arrangement will weigh heavily in the firmness, height, and flexibility of the seat.
A clincher tool (on the left) is used to secure the coil springs to the burlap once their position is decided upon.
The initial twine hand-ties
3. Special upholsterer's twine is used to tie the tops of the springs to just the right height, depending upon the springs chosen, their arrangement, and the desired shape of the seat. Upholsterer's tacks are used to attach the strong twine to the seat box. Boxes made of poplar are tremendously light and strong, ensuring that the tacks will never pull free.
A four-way hand tie
4. In this instance, a four-way hand tie has been used instead of the more rigid eight-way hand tie. This particular seat is designed for a smaller-bodied woman who might have found the firmer tie less comfortable.
These upholstery factors, which have been briefly touched upon here, are a matter of personal preference and are discussed during the initial design process.