How is Mohair Graded?
The value of mohair is heavily influenced by the fineness (usually expressed as Mean Fibre Diameter or MFD and measured in microns (1/1000th of a millimetre)) and, to a lesser extent the staple length (how long the fibres are). Typically the staple length will be from 60mm to 150mm (with a healthy and correctly fed Angora goat their mohair grows at about 20-25mm per month) and an average of 100-120mm. Shorter length fibres are less valuable and may be lost during processing.
Mean Fibre Diameter varies from as little as 16-17 microns in a young kid to as much as 35-40 microns in an larger/older animal. In the South African auctions bags of mohair may be graded into as many as twenty or more grades from super-fine kid through to strong adult and everything in between. Given the volumes produced in in the UK we work on a simpler scale, with three grades (Kid, Young Goat and Adult).
In the show ring much attention is placed on evenness, crimp and curl but these factors are less relevant in the commercial grading of mohair.
Once the mohair arrives with our processing partner it is graded bag by bag to confirm the producer proposed grade is correct. This is carried out by a highly experienced grader who relies on feel, smell, and visual characteristics to make a judgement. This is a highly skilled process and can very accurately assess the difference between 26 micron diameter and 28 micron diameter – a difference of just 1/500th of a millimetre!
This grading process is extremely important from the producers point of view because it can make a huge difference to the value, especially between the Kid and Young Goat grades.
There is quite a bit of confusion about why the MFD of mohair increases. Historically it has always been described as a function of age (i.e. the mohair increases MFD with age) and it is true that this is an accurate description of what happens in most cases. However, there is detailed academic research which reveals that the increase is due an increase in the total skin area (i.e. the MFD increases as the skin area increases due to the growth of the goat (whether as a result of age or better nutrition)). This might be an irrelevant distinction but as a result of improved genetics some Angora goats can avoid “mohair blowout” (when the MFD increases and the mohair becomes coarser and loses value) and keep a finer mohair for several years longer than others – a desirable inheritable trait. There is more detailed information on this in the Research section.