What are the Limits to Wool Fibre Fineness Measurement?

Abstract

Programs attempting to breed commercial sheep flocks averaging 14 microns are now under way. If these are successful the limitations of existing measurement technologies in measuring wool fibres around 10 microns and less may become an important issue.

Both LASERSCAN and OFDA 100 are each capable of measuring the fineness distribution characteristics of such wools. However, it is well known that while both instruments can produce fibre diameter distributions, which include measurements less than 10 microns, for the same sample the OFDA 100 generally "sees" more of these fibres than LASERSCAN. The reason for this has been a matter of conjecture for many years. Furthermore, while both instruments detect a small number of fibres as fine as 5 microns, doubt has been expressed as to whether or not these readings represent real fibres.

A paper presented to the Shanghai Conference of IWTO in May 2001, has attempted to address these issues. The paper reports the results of Scanning Electron Microscope (SEM) measurements of some very fine fibres from an ultrafine (13 microns) farm lot produced in New Zealand.

This article is a critique of this paper, pointing out the along fibre variation as well as other factors can explain the results of the SEM measurements and that these measurements do not substantiate the claims made.

Citation

"What are the Limits to Wool Fibre Fineness Measurement?", P J Sommerville, For TechnoPhiles, AWTA Ltd Newsletter, May 2001