Last update: April 11, 2012 02:20:06 PM E-mail Print

 

Detection of Kemp and Gare in Wool

V. Bosman

 

KEMP and gare fibres are objectionable in the Merino fleece. The manufacturer regards them as defects, and their presence consequently depreciates the value of wool. Kemp is a short, bristly opaque-white fibre, which is thicker than wool fibres. Under the microscope a kemp fibre shows a medulla or central chain of hollow cells in contrast to a wool fibre, which is solid. The medulla contains air inclusions, and this fact has an important bearing on the dyeing property of kemp. A serge suit made from wool with kemp invariably shows the undyed kempy fibres. In addition to the latter objection, the manufacturer experiences trouble in the spinning of yarn from kempy wools.

The fibres of gare are longer than those of kemp, and while the latter sheds itself periodically, gare grows continuously. It is frequently found localized on the britch and neck regions of the Merino, but may also occur through the whole fleece. Gare is a coarser and longer fibre than the adjoining wool fibres, and, like kemp, has a medulla with air inclusions. The medulla is mostly narrower and is often not so visible as in the case of kemp. In Fig. 1 are shown photomicrographs of kemp, gare and wool.

 

 

Method of detection

Kemp and gare are usually distinguishable by the naked eye, but in many cases their detection leaves considerable doubt in the mind of the Merino breeder. A simple method is available by which the farmer can test for kemp and gare. The method consists of viewing the wool sample, immersed in benzol, against a black background. The true wool fibres will be invisible, while the kemp and gare show opaque-white - the latter fact being due to the air inclusions in the medulla of the kemp and gare.

The method is illustrated in Fig. 2. A glass jar, A, is filled with benzol in which is immersed a piece of black paper or cardboard (B). (This paper was taken from that used to wrap up photographic plates and films.) It is advisable to use pure benzol and have the glass perfectly clean, otherwise much of the definiteness of the test may be lost.

 

 

The wool sample to be tested is washed of its grease and adherent impurities. This can be effectively done in a little petrol or benzol. It is, however, not advisable to wash the wool in the same benzol as that used for testing, on account of the liquid becoming turbid and so diminishing the effectiveness of the test. The clean wool sample is then transferred into the testing jar and viewed against the black background in the benzol. Any medullated fibres will show themselves as indicated in the illustration.

 

Application of Test

In addition to testing for kemp and gare in pure Merinos, the detection of medullated fibres may assume significance in wools from Merinos crossed for mutton production. It is of considerable importance to the Merino wool industry of South Africa that such wools are kept separate from true Merino wool. The above test has also been used for detecting medullated fibres in wool samples and estimating the quantities present on a quantitative basis.

 

Published

Farming in South Africa 8