The scutching process removes the impurities and the woody straws from the flax fiber. The resulting fiber goes through the process of “heckling“.
The heckling machine consists of many combs with varying pin density. The strand of fibers is held in place and the combs pass through them with vertical strokes. This process achieves three things:
- Removal of any last bit of straws and impurities from the fibers.
- Separation of the short fibers from the long fibers.
- Straightening of the fibers.
Flax fibers take the length of the flax plant’s stem. To transform these limited-length fibers into one long sliver of fiber, we go through the Mixer process.
The Mixer process “mixes” the fibers together to form one long continuous sliver.
The machinery takes the strand of fiber and passes it through rotating cylinders which hands them to combs with varying number of pins. The pins help straightening the fibers and the cylinders help with mixing them.
The mixer machine outputs its continuous sliver into a big container (typically a cylinder). The length of the sliver depends on the capacity of the cylinder container.
We then take several cylinders from the mixer and use them in the next step, which is “drawing”.
Drawing is the stage that comes after Carding or the mixer. It is the step right before spinning the sliver into yarn.
Drawing is a very important stage because it improves the consistency of the yarn. The main concept is simple: the rule of averaging. By mixing slivers that came out of the carding/mixer together, we reduce the likelihood of sliver inconsistency.
As mentioned under the “Carding” tab, the carding/mixer machine converts fibers into one long sliver in cylinder containers. We then take several slivers from several cylinders and feed them into the drawing machine. The drawing machine mixes the slivers from all the cylinders together. Then, it draws (i.e. pulls or elongates) the mixed slivers to generate an output sliver. The output sliver has better consistency since it takes fibers from all the slivers.
Generally speaking, the higher the number of times we draw the sliver, the more consistent the final sliver would be. The decision as to how many times we draw the slivers together is a complex decision. It depends on the type of the fiber, the consistency of the sliver, and the yarn count we want to achieve at the end.
Spinning is the stage the transforms slivers of fiber into threads.
Spinning machines usually have several heads. Each head works on one sliver to output one cone of thread. The machine usually has many heads in order to parallelize the production. Each cylinder of sliver gets converted into a cone of thread. We later take the cone of threads to the finishing phase where they can get any combination of finishes: twisting with other threads, polishing, bleaching or coloring, winding the thread as balls or spools, and packaging.
There are three methods of spinning: dry, semi-wet, and wet. Wet spinning puts the thread inside a bath of liquid during the spinning phase where the sliver gets twisted in high speeds into thread. The semi-wet method involves water only in a certain part of the process. Dry spinning does not involve any liquid in the process. Adding liquid to the spinning prevents the thread from breaking. It improves the tensile strength but also adds complexity and cost to the production. Therefore, dry spinning method cannot be used with finer threads or yarn with high tensile strength requirement.