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UNITED STATES DEPARTMENT OF AGRICULTURE 
DEPARTMENT BULLETIN NO. 1319 
Washington, D. C. 
April, 1925 
GINNING PIMA COTTON IN ARIZONA 1 
By James S. Townsend, Associate Technologist, Crop Acclimatization and 
Adaptation Investigations, Bureau of Plant Industry 
CONTENTS 
Diverse methods used in ginning 
Pima cotton 
Normal equipment and operation 
Picking and storing seed cotton- 
Use of picker-roll cleaners 
Distributing the seed cotton to 
the gin stand 
Feeding the seed cotton to the 
roller 
Construction and care of the 
gin rollers 
Setting the fixed knife 
Page 
1 
5 
Page 
Normal equipment, etc. — Con. 
How the knives function in 
ginning 8 
Adjustment of the moving knife- 8 
Adjustment of the seed grid 
and pusher board 9 
Removing the cotton from the 
roller 9 
Moving the lint cotton from the 
gin stands to the press 10 
Keeping the lint clean 10 
Conclusions 10 
DIVERSE METHODS USED IN GINNING PIMA COTTON 
In tracing the diversity of roller-ginning methods in Arizona it 
is necessary to consider not only the actual ginning operations but 
the different processes or treatments to which the cotton is subject, 
from the delivery of the seed cotton by the farmer to the turning 
out of the finished bale. It will be seen that most of the attendant 
operations, as well as the ginning processes, were conducted in dif- 
ferent ways and with a variety of mechanical equipment that also 
contributed to the diversity of the product. 
1 The use of roller gins in the United States was limited formerly to the districts in 
South Carolina, Georgia, and Florida where Sea Island cotton was grown, but roller gin- 
ning has been required for the Pima variety of Egyptian cotton, which has been grown in 
recent years in Arizona. Under western conditions new phases of the ginning problems 
have been encountered. The labor costs are higher, so that some of the Sea Island methods 
are less applicable. Several types of roller gins were represented in the different ginning 
establishments of the Salt River Valley, with cleaning and handling devices of various 
kinds partly carried over from saw gins, to which the previous experience of many of the 
ginners had been limited. An investigation has been necessary to determine the effects 
of different treatments at the gins upon the appearance and commercial value of Pima 
cotton. 
On account of differences in the appearance of the bales, some manufacturers of fine 
goods have considered that Pima cotton was not suited to their purposes. The diversity 
in the mechanical condition of the cotton which gave the different appearance undoubt- 
edly has tended to restrict the use of Pima cotton among fine spinners and even caused 
some shipments to be rejected. Thus, the essential uniformity of the Pima stock, which 
has been maintained by careful selection and guarding of the seed supplies, has not been 
20700 c 
-25 
