14 BULLETIN 882, U. S. DEPARTMENT OF AGRICULTURE. 
MERCERIZATIOX. 
The Signal Corps specifications, as given on pages ± to 9. required 
that the cloth be made from yarn mercerized under tension. This 
process usually tends to reduce the amount of stretch and at the 
same time to increase the breaking strength and the doping 4 prop- 
erties of the finished fabric. The results of the tests on gray and 
mercerized yarns, from the three varieties of cotton tested, are 
shown in Table I. Considerable variation existed between the break- 
ing strengths of yarns before and after mercerization. some gaining 
about 10 per cent in strength and others losing about 3 per cent. 
These variations are probably due to difficulties in maintaining con- 
stant mechanical and chemical conditions throughout different lots 
of yarns during the process of mercerization. It should be realized 
that exact duplication of yarn mercerization is almost impossible. 
It was realized that if physical properties of piece mercerized cloth 
equal to those of cloth made from mercerized yarn, could be obtained, 
a tremendous amount of time, labor, and money could be saved. With 
this in mind, a large amount of gray cloth of plain weave was made 
so as to determine the feasibility of mercerizing in the piece instead 
of in the yarn. This fabric was then turned over to a finishing plant 
and mercerized in the piece, after which it was tested and found to 
have less stretch than fabrics woven from mercerized yarns, and at 
the same time practically the same strength. In almost all of the 
yarn-mercerized cloths, the stretch had been greater in the direction 
of the warp than in the direction of the filling, but in the first piece- 
mercerized fabric, the reverse was found to be true. Xot only was 
the warp stretch reduced below that of the filling, but it was found 
that the stretch could be controlled by various methods of finishing. 
This fabric, which was made from the American Egyptian cotton 
from 3 80's yarn, weighed -1.06 ounces per square yard before mercer- 
izing and 3.76 ounces per square yard after mercerizing and at this 
reduced weight had a breaking strength equal to yarn mercerized 
cloth made from similar yarn and with the same construction, at the 
same time it showed the marked decrease in stretch already men- 
tioned. A second lot of the same gray cloth was mercerized in the 
piece by the same firm without direct supervision of the Bureau of 
Markets so as to determine the accuracy with which the strength in 
the warp and filling could be controlled. Very satisfactory results 
were obtained in that practically identical stretch-stress qualities 
were produced for the warp and filling with the added advantage 
of having the stretch approximately one-eighth of an inch less than 
in either the gray or yarn mercerized fabrics. The results of these 
tests are shown in Table 10. 
* See pa ire 38 for definition of doping. 
