The piece-dyed route puts dyeing after the whole piece has been woven — the mills on this route run gabardine, serge and flannel qualities dyed by the piece. This route makes two choices in wet-finishing preparation before dyeing — the order of crabbing and scouring, and whether an extra fabric-level shrink-resist stage is needed for machine-washable or deep-shade orders — and the shrink-resist stage is the one unique to this route. QL supplies every wet- and dry-finishing station from crabbing through pre-shrinking and decatizing in the dyeing and finishing workshop, plus yarn steaming in the weaving workshop.
Piece-dyed versus top-dyed worsted: where dyeing sits in the route
The piece-dyed route puts dyeing after the whole piece has been woven, the opposite of the top-dyed route, which dyes the tops before spinning. Woven greige goes first to inspection and mending, then into wet-finishing preparation, where the order of crabbing and scouring depends on the fabric quality (next section). Standard qualities go straight to piece dyeing or bleaching once prepared; qualities needing machine-washable treatment, deep shades or pre-printing take an extra Kroy pre-treatment stage first (next section). After dyeing, the wet piece is washed, hydro-extracted and dried, then moves into dry finishing, closing with decatizing.
Preparation: how crabbing and scouring set the fabric up for piece dyeing
Preparation forks in two places: whether crabbing sits before or after scouring, and how scouring and wool milling are combined. The mainstream order scours first — washing spinning oil, size and soil out of the greige before crabbing, so none of it gets set into the face in the hot-liquor bath. Qualities with sharp patterns or a tendency to distort take the other order, crabbing first to relieve weaving stress before the wash. Either way, crabbing itself is a batch-or-continuous choice: the WPF-ZN batch crabbing machine (a single bath with twin cylinders reciprocating, one heat history end to end) or the WPF-LXZH continuous crabbing and drying line's crabbing section (five submerged baths in series, each pressed flat and charged with its own liquor). Scouring forks by quality: clear-finish types — gabardine, serge — are scoured only, on the WPF-XN rope scouring machine for most everyday greige; crease-prone qualities such as mohair, silk and synthetic fibres go to the WPF-JXPX open-width washing machine instead, running straight on to crabbing. Face-finish types such as flannel take a light milling step besides scouring — separate machines for steady single-colour batches (WPF-1S milling into WPF-XN rope scouring), the combined WPF-4XS for batches mixing colour and weight, or WPF-1S followed by open-width washing on the WPF-JXPX for qualities that should not go back into rope form.
Piece dyeing and machine-washable treatment: when it is needed
Standard qualities go straight to piece dyeing or bleaching once prepared. Machine-washable shrink-resist finishing, deep shades or pre-printing treatment call for an extra stage first — the Kroy fabric soft-lustre line's fabric-level chlorination shrink-resist pre-treatment. The fibre surface has to be descaled before dyeing, not after — dyeing first and descaling afterwards strips the colour back out — and QL covers this stage with pre-owned refurbished equipment.
Washing, hydro-extraction and drying after dyeing
The dyed piece is washed to rinse off loose dye and residual chemicals, then hydro-extracted before it is dried, and keeping the steps separate is faster than combining them — mechanical squeezing presses out most of the water first, and only the remainder is left for heat to drive off. Drying itself is then a choice between adding the WPF-LXZH continuous drying section (cylinder-type) or keeping the drying equipment already on the floor, with neither having to replace the other: the continuous drying section uses PTFE-coated cylinders, tier-by-tier temperature control and alternating double-face contact to head off the glazing and stiffer hand wool often picks up on cylinders, then cools the fabric with cold air before plaiting. Where the existing dryer already meets output and handle requirements, keeping it works just as well.
Dry finishing: pre-shrinking, decatizing and the handle decision
Dry finishing starts with moisture: the WPF-PP rotating disc moistening unit brings fabric coming off the dryer, usually below its normal regain, back up, since raising, shearing, pressing and decatizing all need that moisture to work. The next fork is by quality — face-finish types that have already been milled go to raising, to lift the pile, and clear-finish types go to shearing, to level the surface; QL currently covers both with pre-owned refurbished equipment. Either way the piece then goes to brushing on the WPF-SM Vertical Brushing Machine, combing the disordered fibres left by raising or shearing back into one direction and clearing loose debris, then on to calendering, also pre-owned equipment, for a temporary lustre.
The pre-shrinking choice is two-way, and it also decides where weft straightening sits:
- Pin-chain: the WPF-LTYS pin-chain steaming-shrinking machine locks the width throughout, so straightening on the WPF-ZW pin-wheel weft straightener happens first, at infeed.
- Belt-type: the WPF-WDYS belt-type steaming-shrinking machine lets the fabric relax freely, so straightening comes after.
Decatizing is the last step, and the one where shade variation and head-to-tail variation are most likely to show — both mostly trace back to steam reaching the width unevenly, with condensate dripping inside the steam-rise chamber adding local hot spots; the choice among four options comes down to throughput and how deep a set is needed:
- Continuous (covers fringed qualities): the WPF-LXZN continuous decatizing machine builds the heating bank into the chamber itself to stage the temperature up and prevent that condensation, paired with QL's proprietary Decatizing Uniformity Technology so steam reaches the full width in sync, solving both problems at the source; fringed scarves, shawls and other categories needing uninterrupted fabric travel cannot be processed on batch decatizing equipment at all — this is the only route for them.
- Batch (for a deeper set): the WPF-JXZN-MAX discontinuous decatizing machine runs a Ø2000 oversized cylinder with the Micro-Pressure Uniform Steaming Technology to take it further.
- Continuous-pressure (deeper set without stopping): the WPF-LXZN-P continuous-pressure machine raises the vessel to 0–3 bar, reaching kier-grade depth even at continuous throughput.
- Kier decatizing: QL supplies pre-owned refurbished equipment.
The last fork is by handle: standard qualities go straight to final inspection and rolling, and qualities wanting a loftier, softer hand add an air-flow softening step, also pre-owned equipment.
QL machines on this route
- Yarn steaming autoclave WPF-ZS: sets twist on the spun yarn in the weaving workshop
- Crabbing: batch on WPF-ZN, continuous on the WPF-LXZH crabbing section — a permanent set for the piece
- Combined scouring and wool milling machine WPF-4XS: scours and mills mixed-batch fabric on one machine
- Multi-channel rope scouring machine WPF-XN: rope-form removal of spinning oil, size and soil
- Open-width washing machine WPF-JXPX: open-width wash without creasing, for distortion-prone qualities
- Wool milling machine WPF-1S: light wool milling for face-finish qualities
- Untwisting and open-width spreading (some lines add mangling): pre-owned refurbished equipment
- Kroy fabric soft-lustre line: fabric-level chlorination shrink-resist pre-treatment for machine-washable, deep-shade or pre-printing orders; pre-owned refurbished equipment
- WPF-LXZH continuous drying section: cylinder-type drying with tiered temperature control against glazing
- Rotating disc moistening unit WPF-PP: reconditions fabric after dyeing and drying
- Raising / shearing: chosen by face-finish or clear-finish quality, pre-owned refurbished equipment
- Vertical Brushing Machine WPF-SM: combs the nap into one direction, removes debris
- Calendering: pre-owned refurbished equipment
- Weft straightener WPF-ZW (pin-wheel type): straightens ahead of pin-chain pre-shrinking
- Pin-chain steaming-shrinking machine WPF-LTYS: width-locked throughout, suits wovens
- Belt-type steaming-shrinking machine WPF-WDYS: free-width relaxation, suits knits
- Decatizing: batch on WPF-JXZN-MAX, continuous on WPF-LXZN, continuous-pressure on WPF-LXZN-P; for kier-grade depth, QL supplies pre-owned refurbished equipment
- Handle improvement (air-flow softening): pre-owned refurbished equipment
Bring your fabric types, batch sizes and current machine list to QL and we talk process before configuration: WhatsApp +1 380 900 2442, or +86 189 2110 8080.