Well the wonderful Sara from Sara's texture crafts kindly explained to me so i thought i would share:
Generally for easy and feltmaking you are looking for a micron close to Merino 64's (21 micron)... so a low micron number is usually good. However, just to contradict that Shetland is a much thicker fibre (and so a higher micron number) and this felts wonderfully, although with a little more work. The reason for these types of exceptions I think are due to the scaley nature of the hair/individual fibre... the more scaley it is the easier it lock together and creates felt (like afro hair makes great dreads). This fibre is often less shiney as a result. Another exception is Alpaca which has a quite low micron number, but is so shiney (hardly any scales) that it is a nightmare to felt on it's own... but can be done.
All in all I'd say avoid shiney fibres and stick to matt fibres... these have more scales (causing less light reflection, so no shine) and should be easier to felt, sticking to a low micron number should make felting quicker too.
Hope this helps you all!!!!
the whole time :]]]
