EDITORIAL 



THE TENSILE STRENGTH OF MACHINE- AND HAND- 

 STRIPPED ABACA FIBER. \ 



Promoters of hemp-stripping machines have from time to time main- 

 tained that the hand-stripped fiber is not as strong as the machine- 

 stripped hemp. It is of considerable importance to the Manila hemp 

 industry to substantiate these claims, as there seems to be little doubt 

 but that in a few years a large part of the abaca leaves will be stripped 

 by machines, and if the machine-stripped hemp is stronger than the 

 hand-stripped variety, the whole Manila hemp industry will be very 

 materially benefited. The present active competition which Manila hemp 

 must meet with the sisal and maguey fibers is largely due to the fact that 

 these latter are machihe-stripped, and consequently more uniform and 

 stronger than retted or hand-stripped fibers of the same species. 



I have made tests on the comparative tensile strength of machine- and 

 hand-stripped abaca fibers. In the first series of tests, stalks from the 

 same plantation of the same age were selected at random, one-half were 

 stripped on the machine and one-half by hand. The latter represented 

 the best grade of hand-stripping, with a smooth-edged ' knife, and the 

 resulting hemp was much cleaner than that usually found in the market. 

 While the above method of selection would not be rigid without a very 

 large number of tests, still the results obtained so markedly and uni- 

 formly point in the same direction that little doubt is left as to the 

 relative strength of the fibers. In making the tests, ten fibers at one 

 time were twisted together and the number of kilos necessary to break 

 them measured with a Eiehle testing machine. Fifty lots of ten fibers 

 each of hand- and machine-stripped hemp of the same length were then 

 weighed to obtain the average weight of the fibers, so that any differences 

 in breaking strain could not be ascribed to different sizes of the fibers 

 used. An arbitrary strength factor X was then calculated, representing 

 the breaking strength divided by the weight of the fibers. The results 

 of the first series of tests are presented in Table I. 



* These tests were made possible through the kind cooperation of Mr. M. A. 

 Clarke, the machine used being that of the Manila Hemp Machine Company. 



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