MANUFACTUBHSTG TESTS OF COTTON STANDAKDS. 5 



STRENGTH OF YARNS. 



Each grade of cotton was spun into 22's yarn. The turns per inch 

 inserted were 19.9, 21.1, and 22.3, using twist multipliers of 4.25, 

 4.50, and 4.75, respectively. 



In the cotton-testing laboratory at Washington each grade and 

 twist was reeled into skeins of 120 yards and broken under constant 

 relative humidity conditions of 65 per cent at 70° F. 



Table 5. — Comparing the breaking strength of 22's yam with different ticists. 



Twist multiplier. 



Turns 



per 



inch. 



L.M. 



G.M.Y.T. 



M.Y.T. 



L.M.Y.T. 



G.M.Y.S. 



M.Y.S. 



G.M.B.S. 



M.B.S. 



4.25 



19.9 

 21.1 



22.3 



Pounds. 

 79.9 

 81.3 



77.3 



Pounds. 

 84.2 

 85.7 

 81.9 



Pounds. 

 89.0 

 88.5 

 82.6 



Pounds . 

 79.1 

 81.2 



77.2 



Pounds. 

 83.4 

 87.2 

 82.6 



Pounds. 

 82.1 

 82.9 

 77.1 



Pounds. 

 76.1 

 76.6 



73.2 



Pounds. 

 75.8 



4.50 



79.5 



4.75 



77.5 







Table 5 shows that the yarn of each grade spun with the twist 

 multiplier of 4.50 was the strongest. This fact is very important 

 because the twist multiplier of 4.75 is usually used as a standard for 

 warp yarns where strength is required. There is one exception to the 

 above fact ; in the case of the Middling Yellow Tinged the strongest 

 break per skein was obtained with a twist multiplier of 4.25. This 

 difference, however, is so small that it is scarcely to be considered. 



The yarn with 21.1 turns per inch, or the 4.50 twist multiplier, 

 broke on an average 2.05 per cent stronger than that with 19.9 turns 

 per inch, or 4.25 twist multiplier, and 5.32 per cent stronger than that 

 with 22.3 turns per inch, or the 4.75 twist multiplier. 



Comparing the breaking strengths of the yarns with the same 

 twist, there appears to be no definite relationship between the strength 

 of the yarn and the grade of the cotton from which it is spun. 



Arranging the grades in the order of their strength values, a 

 slightly different order is observed than when they are arranged in 

 the order of their waste values, the order of strength values being 

 Middling Yellow Tinged, Good Middling Yellow Stained, Good 

 Middling Yellow Tinged, Middling Yellow Stained, Low Middling, 

 Low Middling Yellow Tinged, Middling Blue Stained, and Good 

 Middling Blue Stained. 



The breaking strength of the yarn was also tested by the single- 

 strand method. The results of these tests are shown in Table 6 and 

 indicate a slight difference in the relationship between the strength 

 of the different grades from that found in the skein tests. 

 55812°— 21— Bull. 990 2 



