The following images were made in the University of Leeds’ Electron Microscopy & Spectroscopy Centre  by Dr Eric Condliffe, Principal Research Officer in Earth Sciences, using an FEI Quanta 650 FEG ESEM.  The samples were prepared by Dr Cunliffe, who also annotated the images, by picking the narrowest and widest fully visible measurable fibres in each image.

Left is an image of a superfine merino wool fibre used in our MAPP fabric.  Note the definition of the scale and the linear striations which are essential to the hygroscopic function of the wool.  Click on the pic for a larger image.

In every fabric you will find a range of micron counts.  However the average should always fall within the above limits to be classified accordingly. As a rule of thumb, the narrower the  range of micron counts the higher the standard of sorting and subsequently the higher the quality of fabric.  The wider the range, the lower (and cheaper) the standard of sorting and subsequently the poorer the quality of fabric.  This is because with a greater range of micron counts, the harder it is to create a strong even yarn that will not pill and itch when processed into fabric.  

The following are comparative images of a number of samples taken from leading merino brands.  The samples tested were all taken from garments bought from leading retailers, and only one of each was examined. These are the ranges of micron count found in the fabric samples tested:

•  CF Taranaki 190    13.38µ - 23.00µ*
•  Image 2                  14.42µ - 23.5µ
•  Image 3                  15.61µ - 28.95µ
•  Image 4                  13.22µ - 24.76µ
•  Image 5                  15.66µ - 29.37µ
•  Image 6                  13.61µ - 32.49µ

* This figure is an estimate of the width of a partially hidden fibre that could not be properly measured. The widest measurable fibre was 18.95µ

In addition, there are numerous merino sheep bred for meat, whose wool does not meet the classification standards above. This can quite legally be described as “merino”.  By chemically stripping away out layers using chlorine and acid,  the micron count can be reduced.  However the performance of the wool will be affected as this removes the natural outer waxy layer that gives merino it’s resistance to moisture.  From the images above, it is our belief that some of the wool found in the samples may have been chemically altered in this way to reduce micron count.

Some brand labels are trying to get round the legal definition set down by the Australian and New Zealand Wool Testing Authorities and UK Trading Standards by using the terms “superfine” and “ultra fine” to describe the knit of their fabric.  This, quite frankly is nonsense.  It is irrelevant how fine the knit of a garment is. If the wool yarn being used contains a high enough percentage of fibres over 22µ, it will not be itch-free.

Below are more results of our electron microscope examinations. Click on the pics to see larger images

The standards for NZ Merino bred for wool are based on the following average micron counts:

• Strong wool  24-25µ,
• Medium wool  22-23µ,
• Fine 19-21.9µ,
• Superfine 17-18.9µ,

• Ultrafine under 16.9µ

We were surprised to find micron counts higher than 25 in the samples as we thought these would fall into the Fine Crossbred, Medium Crossbred and Broad Wool categories.

In this sample (right) the micron count of wool fibre used goes up to 23.5µ. This is the coarsest grade for New Zealand Merino.

In this sample (right)the micron count goes up as high as 32.49µ    

The sample (left) shows a micron count with a wide variation in fibres - here from 15.66 right up to 29.37.  

The sample seen here (right) shows micron counts from 13.22 up to 24.76.

The sample seen here (right) shows the micron count and variation in the MAPP superfine fabric we used for our own Taranaki 190 range.

Below are images of merino wool fibres used by other brands.  According to information from the New Zealand Wool Testing Authority lack of scale and striation definition may be indicative that the wool had been chemically altered to reduce the micron count.  However further testing would be required to confirm this.   Click on the pics to see larger images.

Above is an image of clean but otherwise raw wool fibres courtesy of  CSIRO Australia for comparison purposes.

The above results may, of course be none-representative as we have only been able to have a small number of samples tested.  However as a result of our preliminary findings we are now in the process of arranging to have samples tested more thoroughly by New Zealand AgResearch to determine the accuracy of the above.  As one of their leading researchers said to us, it’s not unexpected to find some ‘coarse’  fibres in the distribution, but certainly it’s an issue if there are a lot of them.

In this sample (left) the micron count of wool fibre used goes up as high as 28.95µ.