Alpaca Articles

ALIGNING FIBRE - Part 4 of a 6 part series

By Nic Cooper Southern Alpacas Stud

Part 4  A logical view on those ephemeral factors 

Wow, look at that crimp!

Processors vary in their views on crimp. Few rate it highly, only the real large processors have a preference as to the specific crimp style or uniformity. (See Schneider Mill comments in Part 3).

Woollen processors are supposed to like crimp to put loft (bulk) in the yarns (in wool at least) – whilst traditionally it is largely irrelevant to worsted mills.

Some mills have preferences – the Italian mills prefer low amplitude high frequency crimp, whereas Asian mills have more of a penchant for a bolder crimp style. However in the smaller local mills, crimp is irrelevant as a mill selection criterion as they are simply looking for the right volumes of the correct micron and length.

Pictured - A high frequency, lower amplitude crimp

The main benefit of crimp to a mill is that it creates “stickability” - the extent to which the fibre holds together especially during the early process stages. Many mills have problems with alpaca sliver and rovings breaking and not hanging together because alpaca has inferior crimp to wool, and a fibre scale edge height (very low) that encourages slipping of fibres against each other. 

This has been the main reason mills have encouraged mixing alpaca with wool in processing.

Grower analysis indicates that various aspects of crimp may be a visual indicator of the type of fleece you are producing.  

Crimp frequency (the number of crimps per inch) in sheep is meant to be a reasonable indicator of fineness (micron) with more crimps per inch indicating finer fibre. The relationship is not as strong in all alpaca, but there is a close relationship in highly aligned fibred alpacas (Holt 2006.   The Holt papers on crimp are recommended reading). 

Pictured - Lower frequency higher amplitude crimp

I must here distinguish between crimps.

“Staple crimp” is what you see when a dense alpaca bundles the fibres together in a highly aligned state -  basically what the judge sees and comments on in the Show ring.

“Fibre crimp”, also called crinkle by Holt, is the crimping in the individual fibre and what is measured as curvature by the OFDA 2000 machine.

It is the fibre crimp which defines bulk, which is important to (woollen) processors. Staple crimp can be indicative of fibre crimp, but they are not the same.

Interestingly worsted processors are also starting to get interested in fibre crimp, as it appears to have a measurable effect on the processing performance of the fibre and creating differences in end garment appraisal.

The crimped structure of wool is closely related to the bilateral arrangement of the orthocortex and the paracortex, each of them being associated with a specific organisation. Orthocortical cells are localised in the outside of the crimp and paracortical cells in the inside.

The microfibril-matrix arrangement is much more regular in the paracortex than the orthocortex. As a result, density and matrix to fibrils ratio are higher in the paracortex which has a greater level of di-sulphide bridges than the more fibrous orthocortex.

Furthermore, the chemical composition varies from the paracortex to the orthocortex.

The complex (and little understood) arrangements and compositions of the two cortex's of a fibre have a large influence on crimp in an alpaca. Clearly if it is little understood, it is hard to scientifically breed for. (see also heritabilities).
 

As with everything it seems, there is a process that can artificially add or enhance fibre crimp during processing - the processor doing the job the grower can not. Alpaca fibre in USA entering a denim manufacturing process has crimp patterns established by machine to create a very uniform crimp across the batch.  Most mills that establish their own crimp (synthetic or cotton/silk processors) chose to establish a high frequency, low amplitude, crimp style.

Curvature (the degrees of change of angle of the fibre per mm fibre length) is a measurement from the (OFDA 2000) histogram and in wool, higher curvature figures can assist the processing of the fibre especially in top making and spinning. This relationship does not necessarily hold true in the lower curvature alpaca and curvature is not a factor that mill owners actively seek. 

Research by RIRDC (2003) has shown that resistance to compression (bulk) is one area where alpaca fibre appears to act differently to sheep wool. In sheep wool it is proven that crimp (curvature) is the prime creator of bulk. This is not proven in alpaca, as it has a far less well developed crimp and curvature structure, and a much lower fleece scale edge (making it more slippery).

A word here on “memory”. Fibre has memory that allows it to react to and retain the influence of events that happen to it, particularly moisture, temperature and pressure. These changes can have significant effect on the bulk in a garment, and tend to be most prominent through the processing of fibre. Bulk (crimp etc) in the garment may be very different from that predicted by the OFDA 2000 curve test on the raw fleece.

Mathematically curvature is a factor of crimp frequency, micron and crimp amplitude. We have dealt with the positive features of micron and frequency.  (High) amplitude seems only to act on (increase) curve, and as such its processor effect is minimal.

So the take home point here appears to be that curvature and crimp is not a hugely important factor in the processing of alpaca. However processors with a preference tend to seek high frequency, low amplitude fibre -- the frequency giving the “stickability” and the lower amplitude  giving the benefit of handle. 

There are, however, other effects of crimp (frequency and amplitude) that need to be noted when phenotypically assessing crimp on the alpaca or in a shorn fleece.

1. Crimp frequency seems a good micron indicator, especially in well aligned fleeces. Higher crimp frequency means finer fibre.

2. Curvature tends to parallel crimps per inch. High crimps per inch will normally show a higher curvature, and where it does not, it is the effect of lower amplitude.

3. Hence a higher curvature can tend to indicate a finer fleece - but not always.

4. Similar crimp amplitude looks different in unlike frequency animals. (A high frequency crimp will have amplitude that is far less visually pronounced - but the same or higher curvature).

5. Vicuna – the finest micron, highest curvature, and highest crimp per inch fleece of all the camelids, has a fleece that looks almost straight to the naked eye.

6. High frequency crimp and curvature can mask the handle of the fleece and it will not feel as soft. You are feeling the corrugations of the crimp.

7. High frequency crimp will mask the lustre or brightness of the fleece as reflective light will be reabsorbed in the crimp folds and will not reflect out to the viewer.

8. In alpaca lower curvature may be better for feel and handle. When a batch of garments were returned to a mill as they did not "feel" right, analysis showed the only thing that differed between those garments and an acceptable batch was curvature. (Note this was curve from the processed garment, and could have been process induced, it was not necessarily curve from the originating fibre).   RIRDC (2003) noted the same effect.

These points have significant influence in a show-ring situation and judges need be aware of them and the level of emphasis they put on factors such as crimp amplitude (the wow factor of fleece), and handle which is largely immeasurable, heavily environmental, and at times masked by what appears to be a positive fineness indicator (crimp frequency).

Is lustre just a trick of the light? - Now you see it, now you don't

Lustre is the reflection of light from the transparent cuticle (scale) of the fibre.

Suri has longer scale (cuticle) lengths - hence more reflective surface - and lower cuticle edge height - hence less light reflection disruption so suri is naturally more lustrous.

Lustre is clearly an important factor in suri. However it is worthy of note that in cashmere, lustre is positively discouraged yet in mohair it is treasured.

Great lustre, or light placement?

Huacaya processors do not rate lustre highly. Certainly chalky or dull fleeces should be avoided - but this decision should be made after environmental influences have been eliminated.

One mill commented they did not want to see lustre in huacaya as lustrous fibre tends to slip in the process creating weak points and inconsistency in the yarn. Black alpaca fibre was given as a specific example. Mills also say that “lustre” seen on an animal in the paddock or show-ring bears little relationship to the lustre seen in the end garment.

Lustre is most appropriately commented on once the fibre is washed, the light source is static and focussed and the angle of the reflection/refraction of light is scientifically measured (using a Goniophoto Meter). In huacaya this should be on a stretched fibre to avoid crimp style intruding. On suri it should be on straightened fibre to avoid the negative impact of twisted locks. I do not know of anyone in the alpaca industry who actually measures lustre, although the South African Mohair industry is considering it.

Lustre as seen (or maybe more appropriately not properly seen) on an animal in a paddock or show-ring is hugely influenced by environmental/nutritional factors.

Climatic conditions can create huge swings in lustre - on the same animal - over time. I have spoken to many suri breeders who indicate their alpacas change in lustre, almost from day to day.

In two recent years Australian Judges in NZ have specifically commented in Year 1 that our lustre was hopeless compared to Australia, and in Year 2 that NZ alpaca lustre was magnificent compared.

Year 1 was a drought in NZ and Australia's last wet year for a long while. Year 2 was a wet year in NZ and the first of the Australian drought.

The Australian judges were in many cases looking at the same animals in two different years.

Drought and wind creates dust which coats and scours the fibre, whilst rain clears the dust away.

Some of the best lustre alpacas I have ever seen have been on the Scottish Border - where the locals say it never stops raining and the climate is too wet to breed Suri.

It also helps that these particular alpacas tend to be low curve, low frequency crimp alpacas - making the lustre easier to see.

The dust issue is why we look at lustre near the skin you will say. Unfortunately dandruff similarly taints the skin area.

And with some alpacas producing significantly more grease than others the lustre you see is from the grease coating on the fibre (which of course disappears when the fibre is scoured for processing!).

Finally, the further in towards the skin you look, the less control you have over light source (the sun) and the angles of reflection/refraction.

Nutrition and supplement can radically affect lustre too. Supplements can bring out a glow in an alpaca. On the other hand some necessary treatments can take it away. Zinc supplementation in the North Island for FE appears to suppress lustre (a phenomenon also noted in human hair research).

More About Lustre  
To study “lustre” the appropriate research has actually been done in the human hair field, which is similar to alpaca fibre, but not as fine. The hair product people have done a lot of work on the properties and reasons for “hair shine” which allows translation back to the alpaca.

A) What is shine, or lustre?

It is the reflection of light back from the individual fibre, and light on fibre provides “shine” in several ways:

·         Specularly reflected – giving white highlights and brightness contrasts

·         Diffusedly reflected – giving the fibre a gloss sheen.

·         Internally reflected/refracted – has the colour of the hair in the sheen and is called a “silky” shine.

B) Can lustre be seen properly?

Specularly reflected lustre is only seen at specific light angles (30 – 50 degrees).

Diffused reflected lustre is seen at wider angles (20 – 80 degrees) - but at a lower intensity which varies with angle.

Internally reflected lustre is only seen a higher angles (40 - 80 degrees) and is also less intense.

C) The main influencers for lustre are:

·         Colour (genetic)

·         Surface roughness (genetic and environmental)

·         Cuticle damage (environmental)

·         Hair thickness (micron -  mainly genetic)

·         The presence of medullation (mainly genetic)

·         Fibre damage (environmental)

·         Cuticle (scale) length

·         Cuticle (scale) edge height

Genetic lustre is influenced by a number of attributes - all of them theoretically measurable but few actually measured. Many are not understood as to heritability. 

Micron

Colour

Uniformity of micron (cv)

The alignment of the fibres

The paracortex/orthocortex make up of the fibre internal structure

The height of the fibre scale edge

The length of the fibre scale

Suri inherently scores over huacaya in these last three attributes making it - in reality and after eliminating environmental influences - more lustrous.

The effect of colour on lustre - why blacks are more lustrous

Gloss formation (diffused reflection) appears to be stronger in darker fibres than lighter fibres.

More importantly the gloss index (scientifically measured on clean fibre) appears to fall off more dramatically in longer fibres of lighter fibre than it does in darker fibre. 

On a 150 mm fibre the gloss index of a black fibre is very similar, root to tip. On a light coloured fibre the gloss index at the tip is about 1/3^rd of that at the root.

Genetically we know how to influence micron and cv in our breeding. We do not know how to influence scale length and scale edge height in our breeding, nor can we influence fibre cortex internal make up.

Given all of the above, it is hard to understand the importance given to lustre (or brightness) on huacaya in the show ring. It is such a far cry from the lustre that you may desire in the finished product.

Forget the micron - feel the handle

Comments on handle largely parallel those on lustre. Handle is largely influenced by the same factors and has the same high level of environmental “block” factors when felt on the animal.

Like lustre, handle can be measured (The Specific Pulling Force test – RIRDC 2003). However no breeder does this and handle remains a human judgement. Yet handle is influenced by factors that are measurable - some easily (micron and uniformity) and some less easily (scale height and length).

One cannot deny that handle sets alpaca garments apart from its competitor fabrics.  When a retailer talks about handle they are talking about the handle of the final garment and/or intermediate product (the top, processed yarn or fabric).

However processors buy (primarily) on micron, not handle. When they talk of handle, it is about the scoured fibre input to the mill and/or the top or yarn output from the mill. Mills indicate that handle (of a garment) comes more from the micron of the fibre and the processing technique used, than any other factors.

As we all know from hand spinning, the feel or handle of fibre can be radically altered by the machinery and process it goes through (the tightness of the twist on the yarn, the uniformity of length of the fibres in the yarn, the extent of breaks in the process and the methods of fixing such breaks etc).

There is even now a mill based process that can chemically affect scale on fibres so that they no longer have the harsher handle effect as grown.

There is also the OPTIM process for creating “cool wools” which – by stretching and permanently setting ultra fine, low crimp, longer length fibres -  can produce soft, silky, lustrous and ultra cool garments.

Indeed RIRDC found (2003) that the “cool wool” process was very appropriate for alpaca as it allowed the processor to place a tighter twist on the alpaca (hence countering the slippage factor inherent in alpaca) without radically damaging the handle of the end product.

The road from handle on an alpaca in the show ring or paddock to the handle in the finished garment is both long and tortuous.

As with lustre one has to query the emphasis put on handle in the show ring when the main influencing genetic factors – micron and uniformity - are readily available in the measured form and are two of the major assessment factors in a judged fleece show.

In conclusion

The traditional way we as breeders look at, and talk about, alpaca fleece is not necessarily too helpful in the commercial fibre sense.  Likewise we frequently extol virtues of the fibre on our alpaca’s back that are neither truly translatable to the same virtue in the end product, nor are they virtues we can break down to understandable, measurable and therefore breedable traits.  

The final two sections will examine some of he things we, as breeders, currently do not pay too much attention to, but that are vitally important to processors.  We will also try to suggest a model, going forward, whereby the industry can align its messages to breeders (such as through the Show Ring) to better promote usable fibre and fibre thinking.

Part 5   Guard hair and Contamination

Part 6   Aligning industry drivers to the fibre process

Updated July 2009