Shrink-resist and lustre treatment of wool tops is the continuous line ecru tops run before dyeing: chlorination descaling weakens the fibre scales' directional friction effect, and resin plus a softener lock that change in place, leaving a machine-washable Superwash top. The one route-level choice on this line is the shrink-resist chemistry — chlorination-Hercosett is the mainstream route, with the Basolan system available as an optional extra that lets one line run either chemistry. Once that choice is made, the sequence of treatment bowls follows; whether the top then ships directly or goes on to dyeing is a separate, downstream choice. QL covers this line from splicing through the chlorination/resin treatment to delivery: the WPF-NJ Wool Tops Splicer, the WPF-MTFSSG Wool Tops Shrinkproofing Line, and the WPF-PT Wool Tops Coiler.
Why wool felts and shrinks in the wash, and what shrink-resist treatment solves
Every scale on a wool fibre points the same way, so in the wash a fibre's scales hook onto its neighbour's and only tighten, never release — the mechanism behind felting shrinkage. Left untreated, wool can lose almost half its size on the very first machine wash. Shrink-resist treatment exists to break that mechanism: weaken the scales' directional friction first, then cover the gaps between scales with resin to form a barrier, so a treated top should no longer felt-shrink noticeably under normal machine washing. On this route, the WPF-MTFSSG Wool Tops Shrinkproofing Line performs that first step with controlled active chlorine, descaling the fibre continuously and evenly — once the scales are smoothed, lustre and a soft handle come through as well, delivering both outcomes at once. Whether to run the chlorination chemistry alone or add the optional extra station is the next choice, covered below.
Chlorine–Hercosett versus the Basolan system (optional): how to choose
On chemistry, the line offers a choice between chlorination-Hercosett and the Basolan system — two separate, parallel chemistries, not two steps of one process:
- Mainstream · chlorination-Hercosett system: the chlorination unit etches the scale edges continuously with controlled active chlorine, weakening the root cause of felting — the directional friction effect — at source; most mills in the domestic market run this route today.
- Optional extra · Basolan system (one line, two uses): adding a Basolan treatment station handles the descaling instead, and tops on this path bypass the chlorination unit; the same line can then run either chemistry, selected per order, without needing a dedicated line for each.
Which to specify comes down to whether the order mix calls for switching between the two chemistries: mills that never need the Basolan process can run chlorination alone; mills that need to switch chemistries order to order are the ones who add the optional Basolan station. The WPF-MTFSSG Wool Tops Shrinkproofing Line takes either configuration.
What each treatment bowl does: chlorination, neutralising, resin, softening
On the WPF-MTFSSG Wool Tops Shrinkproofing Line, once tops leave the chlorination unit they enter the multi-bowl chemical after-treatment unit, which runs through four bowls in a fixed sequence:
- Neutralising: sodium carbonate neutralises the residual active chlorine, and a sulphite finishes off what remains.
- Rinsing: a water rinse clears the reaction products left by neutralising.
- Resin: Hercosett resin coats the gaps between scales, forming a barrier against interlocking.
- Softening: a softener improves handle and keeps fibres from sticking together.
The order matters: incomplete neutralising leaves resin uptake uneven and can cause yellowing later in drying. Resin applied before the scales are properly cleared does nothing for shrink resistance no matter how much softener follows. On the Basolan path, this stage runs the Basolan chemistry's own descaling and finishing instead, bypassing the chlorination unit, while the remaining bowl sequence stays much the same.
Resin curing and drying: why cure, and what sets the curing and drying conditions
Curing is what anchors the resin onto the fibre permanently: covering the scale gaps with resin is only the first step, and without curing the resin just sits on the fibre surface and washes off after a few launderings, taking the shrink-resist effect with it. On the WPF-MTFSSG Wool Tops Shrinkproofing Line, curing happens inside drying: the through-flow drum drying unit dries the tops while curing the resin in the same pass. Tops coming off that stage hold too little moisture for the regain downstream gilling and spinning need, so a vacuum cold-conditioning box follows to re-humidify and cool them, bringing the top out at an even, stable moisture level. The exact curing and drying temperatures and dwell times are set to the order's process card and customer samples — ask QL for the process sheet.
The treated top: handle, whiteness and machine-washability
Tops coming off this shrink-resist lustre line's delivery section keep essentially the same whiteness and handle as before treatment, with minimal mass loss — the scales, smoothed across the whole line, leave a lustre closer to cashmere and silk, and a softer handle to go with it; shrink resistance and a good handle aren't in tension here. Machine-washability is the core performance this line delivers: under normal machine washing, tops should no longer felt-shrink noticeably, though how long that holds up still depends on proper laundering afterward. At this point treatment is complete — tops either ship directly as Superwash white top, or move on into dyeing, and both paths sit within what the WPF-MTFSSG Wool Tops Shrinkproofing Line delivers; which one depends on the order, covered next.
After treatment: straight to sale, or on to dyeing
Once shrink-resist treatment is complete, tops follow one of two paths:
- Mainstream · on to dyeing: the top moves on to top-dyed recombing; treated tops take up dye more evenly and sparingly, so it makes sense for the shrink-resist step to sit before dyeing in the chain — this is the more common route.
- Shipped directly: the top ships as machine-washable white top (Superwash grade), already carrying the soft, lustrous handle the treatment gives, with no dyeing step needed.
Which path an order takes depends on whether it calls for finished Superwash white top or is headed into the dyeing chain — both sit within what the WPF-MTFSSG Wool Tops Shrinkproofing Line delivers; only the endpoint differs.
QL machines on this route
QL's wool-tops processing machines on this route, in process order:
- Splicing + creel: the WPF-NJ Wool Tops Splicer, joining broken ends so the top feeds continuously without a stop for can changes.
- Chlorination unit / Basolan treatment station / multi-bowl chemical after-treatment / through-flow drum drying / vacuum cooling & conditioning box: the WPF-MTFSSG Wool Tops Shrinkproofing Line, carrying descaling, resin curing and conditioning through in one continuous pass — the core line on this route.
- Delivery section: the WPF-PT Wool Tops Coiler, winding the treated top into cans ready for handling.
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.