The frame of a sofa is made most often from wood, though newer options include steel, plastic, and laminated boards, or a combination of the above. Kiln-dried maple wood deemed free of knots, bark, and compromising defects, is used under the upholstery. The show wood of the legs, arms, and back can also be maple, but sometimes mahogany, walnut, or fruitwoods are used for carved legs or mouldings.
Padding is primarily made from animal hair, particularly hog or horse. Other paddings used in mass production are foam and polyester fibrefill wrap. Some pre-processing may be necessary, as with the pre-matted rubberized hair, where animal hair is arranged and bonded into shape with glue.
Cushions are fashioned from polyurethane foam, polyester fibre, down, cotton, latex, or cotton-wrapped springs.
A sofa may be covered with any choice of synthetic, natural, or blended fabric. Wool and nylon are the best choices in their respective categories of natural and synthetic fibres, but cotton, acetate, rayon, and polyester have their own functional properties. Exterior fabric may be finished with a protective anti-stain coating.
When used, springs are made of tempered steel. A typical sofa calls for 15 yd (13.71m) of burlap and at least 10 yd (9.14 m) of muslin for the interior. All materials are fastened with approximately 1,000 or more tacks, over 200 yd (182.8 m) of twine, and hundreds of yards of sewing machine thread.
Sofas come in three major sizes. The full sofa is 84 in (2.13 m) wide. Smaller versions like the two-seater and love seat range between 60-80 in (1.52-2.03 m). Variations on the standard sofa include modular items, and sofas with special uses such as daybeds or convertible sofa beds. Ornamental designs are not necessarily less durable, but they do not invite casual use. The design of a sofa can be adjusted to the use that will be made of it, and the average size of the people who will use it most. A deep seat, for instance, is good for taller people, but does not easily accommodate shorter individuals. The style of a sofa is generally set by its arms, which double as artistic statements and rests. Some styles of seating furniture are known by the names of these arm designs. The overstuffed sofa is called that in the trade in order to indicate the use of more than one layer of muslin in the foundation.
First the frame is constructed from wood that has been found clear of any defects. The thickness of the wood should allow for the heavy tension webbing to follow. If the frame is not sufficiently strong, it will not bear the weight redistributed into it by the webbing whenever someone sits down. Arms, back, or back sections, seat, and legs are attached. The preferred method is with clean-cut, fitted double doweled glue joints reinforced with comer braces, glued and screwed into place. Each major part of the sofa will have springs attached separately and will also need to be padded separately. Consequently, they are “framed out” with reinforcing slats, arranged around the seat section.
The foundation is then set for padding. Jute, a kind of burlap made in India, is used as webbing. Strips of this material are interwoven, stretched across the frame, and tacked down. Flax twine is then used to strap the springs onto the webbing. Two lines of twine are tacked into position and then tied around a spring back to front. Another pair of lines will run side to side on each row of springs, after all the springs have been lashed into position individually. If heavy-gauge springs are used in the “front row,” these are further tied down with a length of wire. This process is repeated for the back, with special attention to the springs at the base, which are treated like the front row of seat springs. If the back comes in sections (sometimes three for design purposes), then each part is separately tied off, and the twine ends tacked onto the four-sided frame. The same is true for any sides and arms. Each part will be wrapped in its own sheet of burlap after being completely fitted with secured springs. The burlap is cut to size for each part, tacked into place initially, and then tightly lashed to the springs to minimize movement. This is to prevent the springs from wearing through the burlap over time.
Each part is separately padded as well, with layers of burlap and horsehair or chosen synthetic material. The padding is placed in a burlap envelope, arranged on the edge of the seat, pinned into place, and stitched down. As the stitching progresses, the pins can be removed one by one. This roll is then shaped according to design requirements and stitched with special needles and more twine. After this is secured yet still pliable, a layer of about 15 lb (6.81 kg) Sofa of padding is distributed over the whole area of the seat, extending over the roll. The layer is basted into place with long, loose stitches and covered with lighter weight burlap. Tighter stitching divides the seat into two areas called the platform and the nose or front edge. This front part is reshaped with hand stitching. After the shaping is completed, a final, thicker layer of padding is added to fill in dips left by stitching in the burlap and basted like the previous layer. A muslin sheet of covering is applied, stitched into the break between the platform and nose, tightened across the front edge and back across the platform; its edges are tacked into place. Anomalies in the padding are addressed before proceeding.
Every piece and panel that will be fabric covered must be measured and recorded in a cutting list. The fabric is purchased in one piece or lot. The panels are then plotted out in chalk so they match wherever their seams will meet when finally applied. If any of the panels and pieces need to be sewn together before being attached to the padded frame, this is taken care of first. The seat is covered with panels for the platform and nose and hand-stitched into place along the break between them over a layer of cotton batting. The nose is then covered first to check if the pattern continues along the front properly. The covering is fitted over the back or platform end and secured. The arms are covered next after being prepped with their own layers of cotton batting. A fan-pleated arm is a classic look. The fabric is folded into place around the front roll, in a series of pleats that look like an opened fan when finished. A series of strategically placed cuts may be made, so the fabric clears all obstructions presented by the frame. The top, bottom, back, and pleated front are operated on in succession. Temporary tacks are replaced one by one with permanent tacks.
After the sofa is flipped and covered at the base with a cambric (dust cover), finishing touches are then applied. The sofa may be fitted with one of several choices of skirt. Arms may be supplied with welted panel covers. Cushions are made separately to cover the seat. These are constructed most often from a jacket of ticking, encasing two pads that in turn frame an inner core of foam. Each one is covered with finishing fabric panels supplied with a back zipper, so the case can be removed for dry cleaning.
It’s important to consider furniture manufacturing insurance to protect your furniture business and property, no matter what type of furniture you specialise in manufacturing.