Glossary

A federal limit on formaldehyde in composite wood products — plywood, particleboard, and MDF. Enforced nationally, not just in California. Meeting this standard is a baseline, not a sign of quality. It matters most if you are sensitive to airborne chemicals.

Down is the soft, fluffy undercoat of ducks or geese — not feathers. Most cushions use a down-and-feather blend, not pure down. It feels soft and expensive. It also needs fluffing every day and loses shape faster than foam.

Foam is rated by density — how much it weighs per cubic foot. Higher density means it holds its shape longer. Low-density foam (under 1.8 lb/ft³) goes flat fast. Quality sofas use 1.8–2.5 lb/ft³ or higher.

A specific grade of polyurethane foam that springs back quickly after you stand up. It holds its shape longer than standard foam and is more durable under daily use. The benchmark for quality cushion construction.

The standard test for fabric durability. One double rub is one back-and-forth pass of a weighted arm across the fabric. 15,000+ double rubs is suitable for heavy use. Under 9,000 is light residential only. Tested using the Wyzenbeek method.

Cylindrical wooden pegs used to pin frame joints together. Stronger than nails or staples alone. Commonly used alongside glue for a tight, lasting bond.

Coil springs tied by hand to the frame in eight directions — front, back, both sides, and all four corners. More labor than sinuous springs. More even weight distribution. Lasts longer. Standard in quality American-made upholstery.

Forest Stewardship Council. Certifies that the wood in a product came from responsibly managed forests. A sustainability credential, not a quality indicator. It tells you about sourcing, not about how well the frame is built.

Wood from deciduous trees — oak, maple, ash, birch. Denser and stronger than softwood or engineered wood. A hardwood frame resists warping and cracking. Not all hardwoods are equal — kiln-dried is better than green-cut.

How the pieces of a frame are connected. Doweled and mortise-and-tenon joints are strong. Nails and staples alone are weak. Good joinery — combined with glue — is what keeps a frame tight for years.

Wood that has been dried in a controlled oven to reduce moisture content below 6–8%. This prevents warping, shrinking, and cracking after the sofa is built. Green (undried) wood will move over time and loosen joints.

A joint where a shaped tab (tenon) on one piece fits into a matching hole (mortise) on another. One of the oldest and strongest woodworking joints. Rarely used in mass production because it takes time to cut. Common in high-end American and European frames.

A broad term for fabrics engineered to resist stains, moisture, fading, and wear. Usually solution-dyed or coated at the fiber level. Crypton, Sunbrella, and Revolution are common brands. Performance does not mean premium — the weave and density still matter.

S-shaped steel wires that run front to back under the seat. Faster and cheaper to install than eight-way coil springs. Adequate in most residential sofas when properly tensioned and spaced. Can sag over time if the gauge of wire is too thin.

A solution-dyed acrylic fabric made by Glen Raven. Color is baked into the fiber, not applied on top, so it resists fading. Originally designed for outdoor use. Now common on indoor upholstery for its stain resistance and longevity. Not the softest fabric, but among the most durable.

Buttons or stitches that are pulled through a cushion or back panel to create a dimpled pattern. Holds fill material in place and adds visual detail. Hand-tufting is done one button at a time and is more precise. Machine tufting is faster and less consistent.

Interwoven straps of fabric or rubber that support the seat cushion from below. Used in place of or alongside springs. Should be tightly tensioned and attached at both ends. Jute webbing is traditional. Elastic or rubber webbing is common in modern frames.