None of this does any structural work. All of it, done well, is what makes a chair look finished rather than merely covered.
Trimming is the final-pass decorative work that turns a covered chair into a finished one. Done well, these techniques make the piece look unmistakably professional; done badly, they mark it as amateur. There are essentially four trims to know — gimp, welt (single and double), decorative nails, and bottoming cloth — and we’ll cover each in turn. None is hard to apply; the skill is in the patient, regular spacing.
Gimp: covering the joint between fabric and show-wood
Gimp is the woven decorative braid — usually 12 mm wide, in a colour matched to the show fabric — that hides the joint where show fabric meets show-wood on Georgian and Victorian chairs. Without gimp, you’d see the line of tack heads holding the fabric down against the wood; with gimp, the join looks like a single intentional design element.
Gimp (paid link) is sold by the metre off rolls; allow about 3 m for a typical Georgian dining chair, 6–8 m for an armchair. Apply with fabric glue (paid link), running a thin bead along the gimp’s underside and pressing it into position over the tack heads. Where glue is inappropriate (heritage pieces, or where reversibility matters), use gimp pins (paid link) — tiny round-headed nails 8 mm long, in matching colours, almost invisible at three feet.
Gimp is matched to the show fabric, not to the show-wood. A common mistake is to choose gimp that matches the timber colour; this draws the eye to the joint, which is the opposite of what gimp is for.
Welt: piping at fabric seams
Welt — sometimes called piping — is the fabric-wrapped cord sewn into the seam between two cover panels. It does two jobs: it adds a visible line that defines the panel boundary, and it reinforces the seam so it doesn’t pull apart under load. Most modern sofas have welt around the seat-cushion seams, the back-cushion seams, and along the front rail.
Single welt is one cord wrapped in a single strip of bias-cut fabric, sewn into a seam. The cord is usually 4 or 5 mm cotton or paper. The bias cut (45° to the fabric grain) is essential; cord wrapped in straight-cut fabric kinks around curves and looks lumpy. Double welt is two cords side-by-side in one fabric strip, with the show-side seam running between them — used more often as a decorative trim against show-wood (where it replaces gimp on more modern pieces) than as a panel seam. It’s visually heavier than single welt; common on Chesterfields and high-end sofas.
Cut a strip of fabric on the bias, 40 mm wide for single welt or 60 mm for double. Wrap around the cord (paid link); sew tight against it using a piping foot (paid link). We make our own welt for every job; shop-bought welt rarely matches our customer’s fabric.
Decorative nails
Decorative nails — sometimes called antique studs — are large brass or steel nails with rounded dome heads (10 mm diameter is standard) that fix the fabric edge to the timber along visible joins. Used in place of gimp on Chesterfields, club chairs, leather pieces, and any traditional design where the visual weight of the nail line is part of the chair’s character.
Spacing is the discipline. Standard spacing is 25–30 mm centre-to-centre. Closer than 25 mm and the line looks crowded; further than 30 mm and the fabric sags between nails. Mark spacing with a strip of card before driving the nails (paid link); uneven spacing is the most visible amateurish mistake on any nailed-trim chair. Finishes: plain bright brass for traditional pieces; antique brass for Chesterfields and club work; black-finished steel for modern industrial-style work. We avoid the cheap imitation-aged finishes; they look fake and the ‘ageing’ wears off in a year.
Drive decorative nails with a small nylon-faced or rubber-faced hammer (paid link), not a steel hammer. A steel hammer mark on a brass nail head is permanent and obvious. Some upholsterers use a wooden mallet; either works.
Bottoming cloth: the underside finish
The bottom of every finished chair gets a bottoming cloth — usually black polyester or black calico (paid link) — tacked across the underside of the seat to hide the webbing, the tacks, the hessian, and any other structural ugliness from below. It’s the smallest piece of work in the whole project (15 minutes per chair) and the one that customers notice most often when they tip the chair to look at the underside (and they always do).
Cut a piece to the seat dimensions plus 30 mm on every side. Fold the edges under; tack to the underside of each seat rail at 50 mm intervals. Pull tight enough that there’s no sag; not so tight that the cloth tears at the corners. Black is overwhelmingly the standard colour — we have never had a customer ask for any other.
Some upholsterers sign and date the bottoming cloth with indelible marker before fitting, so future upholsterers know who built the chair and when. I’ve done this on every job since the workshop opened in 2024; I hope someone in 2124 will be glad I did.
Tools & materials for this job
- Gimp braid (12 mm) (paid link)
- Gimp pins (8 mm, matching colours) (paid link)
- Fabric adhesive (paid link)
- Piping cord (4–5 mm) (paid link)
- Decorative dome-headed nails (paid link)
- Nylon / rubber-faced hammer (paid link)
- Black bottoming cloth (paid link)
I sign and date the bottoming cloth on every chair that leaves the workshop, in indelible marker. It takes ten seconds. The customer never sees it. The next upholsterer who tips this chair, decades from now, will see exactly who built it and when.
Every workshop signature on a vintage chair I strip is a small message across time from a dead upholsterer to a living one. Some chairs I’ve worked on carry signatures from the 1900s, the 1930s and the 1980s, alongside mine. It costs nothing to add yours; it’s part of the chain.
The dome-headed brass nail dates from the 17th century, when the heads were hand-forged by specialist nail-makers in Birmingham (a centre of metalwork since the 1500s). The dome shape isn’t decorative; it’s structural. A flat-headed nail driven through a fabric edge creates a stress concentration where the fabric meets the head, and the fabric tears. A dome-headed nail spreads the load across a curved surface and the fabric survives.
Birmingham nail-makers were the largest exporters of upholstery nails in Europe by the early 18th century, shipping in barrels across the empire. Local production moved to mechanised stamping in the Victorian period, but the dome shape was kept; it works.
- Gimp matched to wood, not fabric. Draws the eye to the joint; spoils the visual effect. Match to the fabric.
- Welt cut on the straight grain. Kinks at every curve; looks lumpy. Cut on the bias, every time.
- Uneven nail spacing. The single most visible amateurish mistake. Mark spacing on a card strip before driving the first nail.
- Steel hammer on brass nails. Permanent dent, visible forever. Use a nylon or rubber-faced hammer.
- Skipping the bottoming cloth. The customer always tips the chair. Always.
Trims on, nails driven, bottoming cloth fitted. The chair is finished — hard work and good work, ready to leave the workshop. The next chapter is the last in Part Two and covers the one form of upholstery that’s removable rather than permanent: loose covers and slipcovers.
Hand-made welt, matched gimp, evenly-spaced brass nails — the finishing details are where care shows. Send a photo of your piece for an estimate. Get a quote on your piece →