The Mill Processes

Breeding

breeding

Yes, really, good quality yarn starts right here by breeding strong healthy animals with good conformation, that deliver high volumes of lovely long staple, low micron fibre with high comfort factor. Use the very best males available in order to improve the quality of future generations.

Factors that have a huge impact on processing and therefore quality of yarn are - little variation in micron in a given batch of fibre, micron, staple length (preferable at least 90mm – 140mm), very little primary fibre (guard hair) and a Comfort Factor of 95% or more as well as fibre strength and flexibility.

General Care

general-careGood quality fibre grows best on healthy well-nourished animals living peaceful lives. Illness appears to cause brittle, dry fibre that breaks easily, so do everything possible to prevent disease. Keep parasites to a minimum by keeping living areas and pastures clean.

Design and implement a comprehensive vaccination programme. Build a relationship with your local vet. Use every mechanism available to keep flies, midges and mosquitoes at bay. Prevention is always better than cure. A varied diet rich in minerals, vitamins, protein and dry matter as well as plenty of grazing time tends to keep alpaca content and healthy.

Shearing

shearingIt is almost impossible to reverse the effects of poor shearing technique. Your alpaca has spent 12 months growing fleece for you so take good care of harvesting your crop. Prepare your tools and equipment – service the shearing machine, sharpen the blade properly – there is some research that indicates that hot blades causes damage to the hair follicle and this causes an increase in micron grown by these follicles. Have a clean area to do the shearing. Have everything on hand – correctly labelled bags, a sample bag, shearing oil, antiseptic spray in case of nicks and good quality ropes as well as a shearing mat.

Take the time to blow as much dust and dirt from your alpaca before you start. This will help keep the blades sharp for longer which in turn will facilitate efficient shearing. The longer the alpaca is restrained, the more stress is likely to be experienced. Properly restrain the animal and then proceed to examine the fleece in order to assess the various grades of fibre and how it is distributed on the body. You will notice hard course hair (known as guard hair or primary fibres) on the belly, lower legs and to some extent on the chest and neck. It is also to some degree or other, distributed throughout the blanket and is the main cause of "itch" in the yarn and therefore garments made from this yarn. This will determine how you separate and grade the fleece as it is removed from the animal.

Carefully and systematically remove the fleece from your alpaca according to the various grades which you originally assessed. Sort as you shear and take every care possible to prevent the course fibres from contaminating prime fleece. All this care and preparation will make the task of pre-process sorting much easier. Weigh the fleece – fleece weights are valuable and will help you determine the effectiveness of your breeding programme. Leave the bags open in a clean dry place so that the sweat in the fibre can evaporate. This prevents damage and deterioration during storage.

Sorting

Sorting has two stages – whilst shearing and then prior to packaging for despatch to the mill. All fibre needs to be properly sorted – we will not hand sort and clean fibre but simply repackage and return it to you. Processing costs are calculated on received weight so paying to transport and process contaminants which you can remove is a bit foolish. It will also raise the percentage of "processing losses". Lay the prime blanket on a mesh frame if possible, alternatively a clean table.

Pick out all the second cuts, bits of vegetable matter (seed pods, burrs, sticks, hay) as well as poop. Shake to loosen sand and dust – there is still a surprising amount of "stuff" in the fibre despite cleaning with the blower before shearing. The more foreign matter you remove the better your final yield will be and the more yarn you will get from the fleece that you send.

Tumbling, Washing & Picking

Tumbling

We load small quantities of raw fleece into a large gently rotating cage called a tumbler. This allows bits of debris to fall out. Surprisingly, even apparently clean looking fleece yields quite a bit of dust and other bits and pieces.


washingWashing

Fibre is washed in batches of around 6kg using an environmentally friendly solution that strips sweat, skin oils, urine and dust, leaving a soft clean fleece, ready for further processing. Our washing machine is specially designed for alpaca. It keeps the water at the correct temperature and rotates extremely slowly and gently to prevent matting and felting. The clean fresh smelling fleece is then laid out on mesh racks and allowed to air dry.



Picking

Unfortunately, handling wet fleece causes some matting so we pass the fibre through the picking machine. This vicious looking machine has a rapidly rotating drum full of large teeth. The fibre is drawn into the machine in order for the teeth to pull apart the mats. A flow of air facilitates the whole process and a cloud of individual fibres float out of the machine into the picker room. Here we condition the fibre with a blend of mineral oil, designed to protect the delicate fibres and reduce static in the following processes.

Separator

pickingThe separator is also sometimes referred to as the dehairer. A series of rotating cylinders clothed in fine metal spikes can separate fine fibres from courser fibres and vegetable matter not removed either by hand or by the tumbler. In principle, finer fibre will follow the course of the rotating cylinders, whilst the less flexible courser fibre will fall off the rollers and into the collection chambers below.

A fine mist of fibre exits from the final cylinder into a collection bin, ready for carding. Cylinder speeds are variable so a bit of skill and patience is required to judge the optimum speeds for the best quality with a minimum of loss. Fibre with a comfort factor of over 95% as well as baby fleece will not benefit from this process. It is an extremely slow and time consuming process.

Carding

cardingThe carder is an amazing machine which is still pretty much the same, in principle, as carders designed in the mid 1700"s. Essentially, fibre is untangled and aligned by rotating cylinders of variable sizes running at different speeds. The cylinders are wrapped in card clothing comprised of fine metal pins or wire teeth. It is central to the process of creating yarn. Now that all the basic preparation is complete, we can take the first step towards yarn. It is now that a decision must be made about what yarn, since the feed and sliver weight needs to be calculated as well as the number of slivers. Each sliver will eventually be spun into an end and the ends plied, so if a 4 ply yarn is required then 4 equal length slivers or multiples of 4 will need to be made from a single batch of fibre.

The carder aligns the fibres into a continuous web which can be consolidated to form a sliver or roving. Careful control of the feed weight ensures a consistent sliver, which in turn translates into a consistent yarn. It is at this point in the process that the sliver can be wound onto a roll known as a "bump" and used for hand spinning. The web can also be wrapped without consolidation onto a large roller to form "batts" for use in felt making. We also have an attachment for the carder which takes the web and wraps it around a core thread to make a strong and durable thick carpet yarn. Carpet yarn can be made from clean leg and neck fibres which is a useful way of using fleece that would otherwise have very little value.

Drafting

draftingFrom the carder, the barrels of sliver move to the draw frame and a process known as "drafting" or "drawing". The draw frame is made up of spiked cylinders running at different speeds. Two or more slivers are combined and as they pass through the rollers, their thickness is reduces by a "pulling and stretching" process. The sliver exits the draw frame much thinner and lighter in weight than at the start and is now called a roving. Multiple passes and doubling of the slivers, results in a fine even roving, ready for spinning. The roving is exceptionally fragile and breaks apart very easily.

Spinning

spinningSpinning relies to two process – drafting (pulling) and twisting. The spinning frame further drafts the roving and then immediately imparts twist before winding the single onto a bobbin. Twisting provides a degree of strength to a very fine bundle or thread of fibres. The finer the single, the more challenging it is to spin and ply and the longer the process takes. This is why finer yarn is more expensive to make. There are many variables in the spinning process – level of draft, roller pressure and speed, spindle speed and amount of twist.

Here is where all the preparation really pays off and the quality or lack thereof really shows. All second cuts show up as slubs or lumps and short or brittle fibres cause endless breaks in the single.

Plying

Although twist inserted into a single during spinning provides a degree of strength, a strong balance yarn is the result of two or more singles twisted or plied together. The weight of a finished yarn is determined by the thickness of the single and the number of singles twisted together. Generally we spin the single in the S direction and then remove a bit of the twist when we ply in the Z direction.

The whole business of ply can be a bit confusing and contradictory since a 4 ply yarn will not necessarily have 4 singles but relates to the weight of the yarn and can be measured by how many stitches and how many rows it takes to knit a 100mm square on a given knitting needle size. The industry has many ways of expressing the weight of yarn but is seems the most common and standard system in use is known as tex – the number of meters in one kilogram of finished yarn. 10tex is 10 000meters in 1000grams

plying

Steam/Setting & Process Flow

steamingSteaming/Setting

The plied yarn is passed through a steam chamber before being cooled and wound onto a cone. The steam "sets" the yarn, shrinks it a little and prevents it untwisting. The cone winder can catch some of the larger slubs which we then cut out before splicing the yarn.

The meaning of things

We have discovered that there is a vast array of terms relevant to fibre and textiles. Confusingly, some words mean different things in different countries. Here are some that we have encountered along the way and how we understand their meaning.

BATTS web from the carder, layered onto a cylinder and used to make felt.
BLANKETS fleece found on the body of the alpaca.
BUMP sliver from the carder, wound onto a cylinder, ready for hand spinning.
CARD a process of opening and aligning fibres.
CARD CLOTHING the wires surrounding the carder cylinders.
COMB an industrial worsted process whereby fibre is drawn through a series of fine toothed combs in order to remove all short fibres which would create slubs in the finished yarn.
DTEX mass in grams of 10 000m of yarn
ENDS the number to singles to be plied.
FALSE TWIST slight twist inserted into sliver and tops to provide strength between processes.
GUARD HAIR course hairs found on a fibre bearing animal also known as primary or medulated fibres and responsible for the “itch” in finished garments.
MEDULATED FIBRE course hairs found on a fibre bearing animal also known as primary fibres or guard hair and responsible for the “itch” in finished garments.
NOIL short fibres and second cuts seen as small blobs in the carder web. They appear as slubs in spun yarn and can be removed by an industrial comb.
PLY the process of twisting two or more spun threads together to create yarn.
PRIMARY FIBRE course hairs found on a fibre bearing animal also known as guard hair or medulated fibres and responsible for the “itch” in finished garments. Ply – the process of twisting two or more spun threads together to create yarn.
ROVING a sliver once it has been reduced in weight by drafting.
SCOUR the washing process to remove skin oils, sweat, dust and urine from fibre using a cleaning solution and heated water.
SECOND CUTS very short pieces of fibre created during shearing.
SEMI-WORSTED a more refined process than woollen but without combing.
SINGLES the individual thread created by spinning.
SKIRT A FLEECE remove belly and other course fibres from the edges of the blanket leaving only prime fibre.
SLIVER the web from the carder that is condensed to make a thick “sausage” of aligned fibres.
SLUBS lumpy or uneven area in yarn caused by tiny bundles of short fibre.
STAPLE the length of a fibre or fibre bundle.
TEX mass in grams of 1000m of yarn
TOPS slivers produced in the worsted process after many steps of aligning and combing.
WEB opened and aligned fibres coming off the end of the carder.
WOOLLEN a method of creating yarn. Fibres are randomised and not aligned. Yarn has a slightly fluffy rounded appearance and is best suited to knitting. Both long and short staple fibres can be incorporated into woollen yarn.
WORSTED a method of creating yarn. The process is more complex and lengthy and a smooth sleek yarn in produced with highly parallelised long staple fibres. Very strong fine yarns with high twist suitable for machine weaving are made with the worsted process. Slivers are always combed to remove short fibre as well as any noil.

Losses

Before we became involved with processing fibre, we were shocked and somewhat outraged at reported losses of between 30% and 60% and could not comprehend "what went wrong". Our understanding is a little different now. Raw blanket fibre that appears to be "clean" and free of vegetable matter, second-cuts and bits and pieces, loses between 3% and 7% weight during washing and drying. Our conclusion is that this loss is made up of sweat, urine, dust and skin oils and this is verified by specialists in the big mills.

Merino loses up to 40% weight in the scour process. If the fibre is passed through the separator, guard hair is removed – since this course fibre is heavier than the fine soft fibres, it stands to reason that a fair bit of weight is lost here too. A small quantity of fibre is left on the machine during carding and this is essentially unrecoverable other than as waste. Therefore, the larger the batch we process, the less the percentage unrecoverable will be overall.

Spinning takes a fair bit of set-up in order to get the machines working well with a particular batch of fibre. Brittle fibres, lots of slubs and shorter fibres all complicate the process and cause lots of breaks in the singles – so more loss occurs here. In the final analysis, the more consistent the fibre, a very high comfort factor and the strength and flexibility of the fibres play a significant role in the quality of the final product as well as the percentage weight loss.