What is Spinning Fineness (SF)?

The value of spinning fineness (SF) is derived from the Martindale theory on the effective fineness of wool.

SF = 0.881MFD√[1+5(CV%/100)²]

NOTES:

This formula means that a reduction in CV of 5% has the same effect on spinning fineness as a 1µm reduction in MFD.
For example:

A CV of 24% has a zero effect on Spinning Fineness.