Manufacturing · Cap Encyclopedia
Cap Visor Construction
The visor is a plastic sandwich — two fabric covers over a rigid insert, held together by concentric top-stitch rows. Insert grade and stitch-row count are the only two variables that decide whether the brim stays flat or warps.
The visor sandwich
Three parts: top cover, plastic insert, under-visor cover. Top cover is usually the shell fabric (matching the crown); under-visor is a contrast cotton twill (green, grey or black are heritage callouts) or matching shell. The insert sits between them and defines the brim.
- Top cover — shell fabric; the visible surface.
- Insert — HDPE plastic, 0.9mm (soft dad hat curve) up to 1.2mm (rigid flat brim).
- Under-visor — contrast cotton twill or shell match; carries the size tag on some brands.
- Edge — bound with fabric tape or top-stitched raw edge finish.
Flat vs curved brim geometry
Every visor leaves the factory FLAT. The curve is imposed by two things: the shape of the insert as it comes off the die, and steam-blocking after assembly. Snapback flat brims use a straight insert and no post-forming; dad hats use a pre-curved insert plus steam-forming.
- Flat brim: rigid 1.1–1.2mm HDPE, 8 stitch rows, no curve set. Signature snapback look.
- Slightly curved: 1.0mm HDPE, 6 rows, gentle 8–10mm rise at the tip. Fitted-cap default.
- Deep curve: 0.9mm HDPE, 4 rows, 20–25mm rise at the tip. Dad hat and running cap.
Stitch rows — the stiffness dial
Top-stitch rows run concentrically from the crown edge to the brim tip. Each row compresses the fabric-insert-fabric sandwich and adds rigidity. More rows = flatter, stiffer brim. Stitch spacing is typically 3–5mm.
| Rows | Feel | Silhouette |
|---|---|---|
| 4 rows | Soft, curveable by hand | Dad hat, camp cap |
| 6 rows | Medium — pre-curved, holds shape | Fitted, low-profile |
| 8 rows | Rigid, flat | Snapback, streetwear flat brim |
Insert material — HDPE grade and thickness
Cheap caps use recycled polypropylene inserts that warp at car-dashboard temperatures (60°C+). Retail-grade caps use virgin HDPE (high-density polyethylene) which stays dimensionally stable up to 80°C. Buckle specification on your tech pack — "HDPE, virgin, 1.1mm" — or the factory will default to the cheapest option that fits.
Common pitfalls
- Spec'ing an 8-row flat brim on a dad-hat silhouette — the visor stays flat but the soft crown collapses, and the cap sits weird.
- Recycled PP insert on a car-detailer promo run — every cap left on a dashboard warps within a week.
- Skipping the edge bind on a flat brim — the raw stitched edge frays after 6 months.
- Contrast under-visor colour not specified — factory defaults to a random green from stock.
Specify your brim on the tech pack
Send us your silhouette reference — we'll match insert grade, curve, and stitch-row count and press a proto in 10 days.