Here are some useful keywords to understand when buying fibres for felting.

Staple - The term 'staple' usually refers to the length of the individual fibre, or animal hair. The staple length will determine the best end-use of the fibres. For example longer lengths are good for spinning.

Crimp - The term 'crimp' refers to the waves along the length of the fibre. For example the merino I buy has a low crimp number, because it is almost smooth along it's length. However, I bought some Blue Faced Leicester and that is very curly, so has lots of waves along it's length and therefore has a much higher crimp count. It seems that the number of waves across an average 'cm' is how the 'crimp' of a fibre is classified. Apparently the higher the crimp the finer you can spin the fibres into yarn.

Count - Now this seems to be the confusing part and it is often one of the things we are told about when buying fibres... But what is the Bradford Count and I've also heard of a Micron Measurement - what is that?

The Bradford count is a traditional English fibre grading system, while the micro measurement is the most modern measuring system of the two and refers to the measurement of an individual fibre's diameter under a microscope. I am told that this is a much more accurate way to measure fibre as it can be as precise as 1/25000 of an inch!

Both systems are still used today and you may find this information in product descriptions when you are buying your fibres. But what does this mean to me as a felter? Well this is where I was a little stuck too... Let's start with the comparison table (can easily be found on the internet and I have reproduced it here for us to see).

Micron Measurement - Bradford Count
19 microns - 70 Bradford
20 microns - 68/66 Bradford
21 microns - 64 Bradford
22 microns - 62 Bradford
23 microns - 60 Bradford
25 microns - 58 Bradford
28 microns - 56 Bradford
33 microns - 50 Bradford
35 microns - 48 Bradford
37 microns - 46 Bradford

So now we know that if I buy a merino fibre (commonly documented as having a count of Bradford 64/Merino 64s) it has a micron count of around 21. But is that good or bad for a felter? Well from my research it seems that the higher the Bradford number/lower micron number then the finer the individual fibre is. I am also told that the finer the fibre the easier it is to felt, as it seemingly shrinks better under heat and water exposure, especially when worked with soap.

So what fibres are we felters looking for? Well for easy felt making stick to the finer fibres, such as Merino (which I've often seen recommended for beginners) and if you want more of a coarse texture try something with a thicker fibre.

Lustre - 'Lustre' relates to the shine a fibre will give and this is determined by the number of scales along the length of the hair fibre. For example the less scaly the fibre is under the microscope, the more shiny it appears to the eye, especially when spun into yarn.