🪑 Upholstery

What you’ll learn

1. A Chair Is a Suspension SystemRead an upholstered chair as a suspension system — a stack in which every layer hands its load to the one below — and diagnose from the bottom up.A chair's cover has roughly the structural ambition of a shirt; what stops you is a chain running cover → padding → springs → webbing → frame, and load travels down it. Because a chain fails at its weakest link, the layer that failed is almost never the layer you can feel, which is why a sagging seat so often gets expensive new foam laid over stretched webbing and sags again by spring.
2. The Frame Decides Everything Above ItAssess and repair a frame before any upholstery, and judge which frames are worth the work.A loose joint is a self-accelerating failure — every sitting wears the joint, so it loosens further — and upholstering over it seals the problem under new fabric. Old hardwood frames are worth saving precisely because hide glue is reversible: knock the joint apart, clean ALL the old glue off both surfaces, re-glue and clamp square, checking by equal diagonals. All of it happens before a single tack, because the frame is the datum everything above is measured from.
3. Webbing: A Foundation Made of TensionExplain webbing as a tensioned structure, install it with a stretcher and an interlaced weave, and recognise it as the usual cause of a sagging seat.Jute webbing is the entire foundation and it works only under tension — slack it does nothing, drum-tight it holds an adult for fifty years, so the tension is the technology. That tension can't be reached by hand, hence the web stretcher levering against the frame; ends are folded and tacked doubled so the jute can't tear through, and strips are interlaced so load is shared. Jute creeps and embrittles over decades, silently, at the bottom of the stack — which is why the diagnosis for a saggy chair is always to turn it over first.
4. Springs, and What They're Actually ForDistinguish what springs do from what padding does, compare coil and sinuous systems fairly, and diagnose spring faults as tie failures.Springs give the deep, slow travel and padding gives the shallow, immediate softness — two systems doing two jobs, and neither substitutes for the other. Eight-way hand-tying stops a coil leaning or buckling and links the springs into one deflecting surface, which is why it feels expensive: the cost is the string and the labour, not the steel. Sinuous springs are shallower and firmer and entirely honest for low-profile furniture, and in both systems the steel outlives the twine, so a poking spring is a re-tie.
5. Density Is Not FirmnessSeparate foam density from foam firmness, buy on the right number, and weigh traditional hair filling against foam honestly.Density is mass per unit volume and governs how long foam lasts; ILD, under ASTM D3574, is the pounds needed to press a 50 sq in plate to 25% of the foam's height and governs only how it feels. They're independent, so a low-density foam can be made to feel firm in a showroom and pancake within two years — you judged its ILD while asking a density question. Traditional curled hair, shaped by twine stitches borrowed from saddlery, breathes and can be teased and reused; foam is cheap, consistent and fast, and that ratio is why the trade changed.
6. Stripping: The Chair Teaches You the PatternStrip a chair as a documentation exercise, preserving the old cover as the pattern and the frame as the datum.You never draft a pattern — the previous upholsterer's solution is still on the chair, cut to shape, so every panel is a template of itself and the removal order is the fitting order reversed. That makes photographing, labelling and keeping every panel the whole technique, and it's what beginners destroy in the first excited hour. Tacks come out with a ripping chisel along the grain, because fabric torn off tacks chews the tacking rails into a sponge that won't hold new ones.
7. The CoverFit a cover with correct grain direction and tension order, and choose between tacks and staples on real grounds.Woven cloth is strong along the warp, slightly giving along the weft and very stretchy on the bias, so the warp must run front-to-back on a seat or the recovered seat bags out within a year. Fitting means centre front, centre back pulling against it, then the sides, working outward with temporary tacks — start at a corner and every wrinkle gets pushed ahead of you into a permanent pleat. Panels go on in the reverse of stripping so each outside layer hides the raw edges beneath it, and tacks earn their place by pulling out cleanly for the next person.
8. Choosing Fabric — and Whether to Do This at AllRead abrasion ratings as a category gate rather than a durability score, and decide from the frame whether to reupholster at all.ACT publishes the double-rub guidelines and also publishes the disclaimer: twice the cycles isn't twice the life, its 2009 study found at least 60% variance testing the same fabric, results above the high-traffic guideline don't indicate longer life, Wyzenbeek and Martindale don't correlate, and the tests ignore edge abrasion — what really kills fabric is bad cleaning, abuse and misapplication. So gate on category, then choose on weave, fibre and cleanability. And the whole course reduces to one final check: a re-gluable hardwood frame is worth any amount of work, while stapled particleboard should be let go.

Questions this course answers

Grounded in trusted sources

• Upholstery — the traditional layer order (webbing, springs, stuffing, padding, cover); fillings of animal hair (horse, hog, cow), coir, straw and hay, hessians, linen scrims and wadding; curled horsehair held with twine stitches developed from saddlery; serpentine springs among modern materials; webbing stretchers, upholstery hammers and curved needles: https://en.wikipedia.org/wiki/Upholstery
• ASTM D3574 — IFD/ILD measured as the force in pounds to indent a 50 sq in platen to 25% of a foam specimen's height (Method B1); density measured separately as mass per unit volume in lb/ft³: https://www.testresources.net/applications/indentation-force-deflection-ifd-testing-per-astm-d3574
• Association for Contract Textiles — abrasion performance guidelines (15,000 Wyzenbeek double rubs / 20,000 Martindale for commercial low traffic; 30,000 / 40,000 for high traffic): https://contracttextiles.org/performance-guidelines/abrasion-low-traffic-woven-fabrics/
• Association for Contract Textiles, 'Abrasion Disclaimer' — twice the cycles does not indicate double the service life; the 2009 Wyzenbeek Performance Verification Fabric Study observed at least 60% variance testing the same fabric; results above the high-traffic guideline are not shown to indicate longer life; no correlation between Wyzenbeek and Martindale; the tests measure flat abrasion only: https://contracttextiles.org/performance-guidelines/abrasion-disclaimer/
• Foam density rules of thumb (≈1.8 lb/ft³ typical furniture polyurethane; ≈2.4+ lb/ft³ for long-life seating) are trade guidance commonly quoted by foam suppliers rather than a published standard, and are presented as such: https://midwestfabrics.com/blogs/recent-posts-on-our-blog/foam-density-vs-firmness-seat-cushion-foam

Every Wunder lesson is built from real, reputable sources — never invented.

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