IMPROVED COTTON 'AIRPLANE FABRIC. 33 
However, as the above conditions could not be reproduced in prac- 
tice, the following were used as a standard in the laboratory tests : 
(a) Sixty-four degree Twaddle solution of caustic soda. 
(&) Two hundred pounds tension. 
(c) Twenty-five degrees Centigrade wash waters for neutralizing. 
(d) One minute treatment with caustic soda solution before neutralizing. 
(e) No chemicals added to the caustic bath. 
Application of the conclusions drawn from the laboratory tests 
was then made by mercerizing piece goods on a commercial scale in 
a finishing plant where conditions were nearly the same as those 
adopted as a standard in the laboratory tests. The conditions that 
actually prevailed were as follows: 
( a ) Fifty to sixty degree Twaddle solution of caustic soda. 
( & ) Highest tension possible in machine without pulling cloth out of tenter 
clips. 
(c) Wash water 190° to 40° F. 
(d) No additions to the caustic liquor. 
(e) Goods run directly from bale through caustic. 
(f) Goods were mangled (a) through water, (b) through £ per cent starch 
solution, and dried on tenter frames. 
The cloths tested were the special twist cloths represented by 
samples Nos. 8, 9, 11, 12, 13, and 14, as given in Table 12. These 
results are shown graphically in figures 14 and 15. 
From figures 14 and 15 the effect of tentering, starching, yarn 
mercerization, and piece mercerization can readily be seen and may 
be stated as follows : 
(a) Tentering does not materially alter the stretch-stress qualities of the 
fabric. 
{l>) Starching slightly increases the breaking strength, although it is unde- 
sirable in airplane cloth, as it reduces the porosity and thus prevents good 
" doping." 
(c) Yarn mercerization did not materially affect the stretch-stress qualities 
of this particular cloth. 
(d) Piece mercerization decreased the stretch materially (approximately 
one-eighth of an inch in the 8-inch sample tested). 
All of the finished fabrics were clear and bright in appearance 
and of good, firm feel, especially the piece-mercerized fabrics. The 
original piece-mercerized fabric, as shown in Table 10 or figure 15, 
gave the stretch in the direction of the warp considerably less than 
that in the direction of the filling. However, a second piece was 
mercerized to remedy this condition, with the result that the stretch- 
stress qualities were practically equalized, thus indicating that these 
qualities were fully controllable in the piece-mercerization process. 
Having investigated the various physical properties of the above 
cloths in the usual manner, tests were made to determine the effect 
of continual stress upon these fabrics, so as to produce a condition 
