Start with the end of the garment's life

Most clothing is designed around assembly. The pattern is cut, the seams are chosen, the trims are ordered, and the whole thing is engineered to come together as quickly and reliably as possible on the factory floor. Circular design simply asks you to hold a second question alongside that one: when this garment has been worn hard for ten years, how will it come apart, and where will each part go?

Answering that at the sketch stage costs almost nothing. Answering it after the zip tape, the interfacing and the care labels have been specified is expensive, and often means going back to the beginning. The good news is that the changes are rarely dramatic. They are a series of small, specific choices about seams, trims and fibre mixes — the sort of decisions a textile engineer or product developer makes every week anyway.

Keep the material palette compatible

Recycling a garment is only ever as easy as its most awkward component. A 50/50 cotton-polyester shirt is, in practice, almost impossible to separate back into usable fibre with current commercial sorting and mechanical recycling. A pure cotton shirt, or one where the polyester is confined to a panel that can be snipped off, is a straightforward candidate.

• Prefer mono-material construction for the main body and sleeves. If a garment must have stretch, keep the elastane in separate components — cuffs, ribbed panels, waistbands — rather than blending it through the whole fabric.
• Stay within a fibre family where you do need a blend. Wool with a small amount of nylon is far better understood by recyclers than wool blended with acrylic or polyester.
• Audit the hidden parts. Pocketing, linings, fusible interlinings, wadding and reinforcement tapes are the usual culprits. Match them to the shell where you can, or make them easy to cut away.
• Avoid adhesives and bonded or glued constructions. They cannot be unpicked, and they contaminate the fibre during shredding.

Seams that can be undone

A seam is a temporary joint that should be reversible. Overlocking is quick and neat, but it trims the seam allowance, creates bulk and leaves little to work with if the seam needs to be let out or repaired. Where you have the choice, a plain lockstitch on a generous allowance is far more repairable — 15 mm rather than 10 mm gives a tailor something to work with in five years' time.

Stitch density matters too. Around ten to twelve stitches per inch holds well and can still be unpicked with a seam ripper. Push much beyond that and you perforate the fabric, weaken it along the stitch line, and make the seam genuinely difficult to open without cutting the cloth. A locked, well-knotted finish at the ends of a seam is essential; nothing demoralises a repairer more than a seam that unravels as soon as it is touched.

For garments intended for disassembly, consider a chain stitch with a pull thread, or a contrasting thread colour that makes the disassembly seam obvious to whoever is sorting the garment later.

Trims, threads and the small decisions

Trims decide whether a garment can be reclaimed. A metal zip can be unstitched and separated; a moulded plastic zip welded to a tape that is bonded rather than sewn cannot. A few practical rules:

• Choose trims with a clear material identity — metal zips, corozo or nut buttons, or buttons made from the same polymer as the garment.
• Sew everything on. Snaps, rivets, eyelets, gripper tape and heat-transfer prints all defeat mechanical separation. Anything glued or fused should be avoided.
• Match your sewing thread to the main fibre where possible, or use a cotton-wrapped polyester that at least breaks down predictably. A polyester thread through a cotton garment is a small contaminant, but it is still a contaminant.
• Rethink branding and labels. Woven labels in the same fibre as the garment, or printed directly onto the fabric, remove a whole category of waste. Printed care information in ink that washes out cleanly is better than a plastic-coated tag.

Designing for repair, not just recycling

Recycling sits at the end of the queue. The longest life — and the lowest impact — comes from garments that get mended, altered and passed on. Build that in deliberately. Underarm gussets in shirts and dresses add movement and delay the first failure. Reinforced bar tacks at pocket mouths and belt loops stop the fraying that sends garments to the back of the wardrobe. Accessible linings, closed with a hand-stitched opening rather than a sealed bag, let a tailor reach the inside of a coat without unpicking the whole hem.

Include spare buttons on the label, supply a small quantity of matching yarn with high-value pieces, and print care instructions that include repair guidance rather than just washing symbols. These feel like small gestures; in practice they are what keeps a garment in use.

Making it work on the factory floor

Circular design only survives if it can be manufactured at cost and at volume. Take your seam and trim choices to the sample room early and time the assembly. If a mono-material pocket bag adds two minutes per garment, that is a real number you can weigh against the value of the recycled fibre later. If a removable zip requires an extra operation, cost it properly rather than assuming it will be absorbed.

The most useful habit is to keep one sample of every style and, at the end of each season, take it apart on the bench. Time how long it takes, note what snags, and feed that back into the next pattern. Designers who do this once tend to keep doing it, because the answer is almost always the same: the changes are cheap, they are specific, and they start on paper.