Tubular or Open-Width? The Take-Down Route and Why It Matters
Fabric leaving a circular knitting machine is either processed as a tube or slit at one edge into open-width. That single choice governs the finished fabric's identity — from crease-free disperse dyeing and stenter heat-setting to edge marks, width and hand.
A circular knitting machine naturally produces fabric as a seamless tube. One decision taken before wet processing — whether to run that tube as-is or cut it along a wale and lay it out flat and open — sets how it behaves in the dyebath, how cleanly it can be heat-set on the stenter, and the final hand you end up with. This is the 'take-down' route: it never shows up on a machine spec sheet, yet it quietly drives the width, shrinkage and hand lines on the TDS. For the physics of filament and textured yarn see our yarn guides (POY/FDY/HOY, DTY texturing), and for the typical ~130 °C disperse chemistry see our dyeing guide; here the focus is purely the physical path the fabric travels.
Two Routes: Tubular and Open-Width
On the tubular route the fabric keeps the seamless cylindrical form it was knitted in: it is wound folded flat, dyed in rope or open-tube form, dried relaxed and compacted on a tubular compactor. On the open-width route the fabric is slit along a single wale — at the machine take-down or on a separate opening line — and spread out as a flat sheet; from there everything (dyeing, washing, stenter setting, finishing) runs in flat open-width form. The general rule is simple: smooth, plain, dimension-critical or elastane-containing fabrics favour open-width; classic, soft tubular goods stay most economical on the tubular route.
Why We Slit: Crease-Free Dyeing and Setting
Disperse dye colours polyester under pressure at typically ~130 °C (its crystalline, hydrophobic structure demands it). At that temperature the polyester chains become mobile; if the fabric is crammed as a folded tube while this happens, fold lines and rope creases can 'set' as a permanent mark — the dyebath is simultaneously a dyeing and a heat-setting bath. Elastane-containing (jersey/spandex) knits are especially sensitive: elastane retracts under heat, and in a folded tube that retraction freezes in as uneven creasing and a permanent fold mark. Spreading the fabric open-width largely removes this risk: the fabric travels taut and flat, and on the stenter (typical ~180–210 °C heat-setting) the width and shrinkage memory set cleanly. That is why elastane jersey and flat, dimension-critical surfaces are typically slit and run open-width.
Where Tubular Compacting Holds Its Ground
The tubular route is not blindly 'old'; it is the first choice for single jersey, rib and many classic single/double-knit fabrics. A tubular compactor (e.g. Navis TubeTex Pak-Nit/Gemini class, Santex Rimar tubular compactor) mechanically pushes the fabric back between a steam cylinder and felt, drives residual shrinkage down to a representative commercial ~3–5% (premium <3%), and gives the characteristic full, soft, 'washed' hand. The seamless tube look and the fact that no side edge is ever created are preserved — useful, for example, for tubular garments or side-seam-free bodies. The key advantage: because it is never cut, there is no selvedge, so most of the edge-mark issues described below simply never arise.
Effect on Edge Marks, Width and Hand
- Edge marks: In open-width processing the two slit free edges are held by the stenter pin/clip line; pin holes, curling edges and a slit line that is not exactly on a wale can leave a discoloured or skewed edge band — so usable width on open-width is set after deducting edge waste. The tubular route has no free edge and therefore none of this edge-mark class; instead it carries the risk of two fold-line creases.
- Width control: Open-width plus stenter is the most direct way to set width precisely and repeatably (chain width fixes the width); preferred for dimension-critical cutting. On the tubular route, width depends on the tube's natural circumference and the compactor setting, with fewer degrees of freedom.
- Hand and appearance: Tubular compacting tends to give a full, soft, springy hand; open-width plus stenter delivers a flatter, more even, stable surface and better spirality/skew control (relative to ASTM D5430 4-point and AATCC 179 spirality). The same dyed loop becomes a noticeably different fabric on the two routes.
Comparing the Tubular and Open-Width Routes
| Dimension | Tubular route | Open-width (slit) route |
|---|---|---|
| Form | Seamless tube preserved | Slit along one wale, spread flat |
| Best typical fit | Single jersey, rib, classic single/double-knit | Elastane jersey, mesh, dimension-critical flat surfaces |
| Dyeing behaviour | Rope/open-tube; fold-mark risk in folded tube | Flat/taut; creasing and fold-mark risk minimised |
| Heat-setting (stenter) | Usually relax-dry led before setting | Stenter pin line sets width/shrinkage cleanly |
| Edge | No free edge → no edge mark; fold-line risk | Two slit edges → pin mark/curling, edge waste |
| Width control | Tied to tube circumference + compactor, less freedom | Precise and repeatable via stenter chain |
| Hand | Full, soft, 'washed' | Flat, even, stable; better spirality control |
| Shrinkage closure | Tubular compactor → ~3–5% (representative) | Open-width compactor → ~3–5% (representative) |
How to Choose the Route
- Does it contain elastane/spandex? If so, open-width is the strong default, to avoid uneven retraction and fold marks under heat.
- Is the surface smooth, plain and dimension-critical (lining, print base, technical flat surface)? Open-width plus stenter is preferred for width and stability control.
- Is it a classic single jersey/rib where a full, soft hand is wanted? The tubular route is typically both economical and right in character.
- Does the garment need a side-seam-free / tubular form? Preserving the tube form is the natural advantage here.
- Weigh edge-mark/curling tolerance against width flexibility: open-width gives the most width freedom but brings edge waste; tubular eliminates edge waste but fixes the width.
In a single-roof mill the value of this decision is that the same laboratory controls the knit structure, the dyebath and the stenter setting together: the route can be chosen at the very start — while the greige roll is still warm — against the fabric's final TDS target (width, shrinkage, hand, spirality), without inter-mill transport and re-inspection. For single jersey/rib/interlock structure choices and the logic of weight, see our related fabric-family and GSM guides.
Frequently asked questions
Why is fabric processed open-width (slit)?
Open-width slits the fabric at the edge and opens it flat, which allows disperse dyeing and stenter fixation without creasing or fold marks and clarifies the width. The tubular route instead offers a seamless edge and a particular hand.
Should I choose tubular or open-width?
Tubular for a seamless edge and a specific innerwear hand; open-width for crease-free even dyeing, stable width and most outerwear fabrics.