Moisture has an influential effect on cotton from crop to fabric
There are many differenet ways to measure cotton moisture and many steps in production chain where moisture has to be measured. The technologies have been developed to allow the monitor of cotton moisture and its control in the field, during harvest, storage, ginning, processing in textile mills and quality control in laboratories in compliance wiht Standard ASTM D-1776.
A) HAVERSTING AND GINNING OF COTTON FIBERS
Proper moisture control begins during harvesting period.
In areas where cotton is picked up and it is still damp from morning dew, therefore the cotton will weigh more during the sell.
Cotton that is picked with excessive moisture content is also at risk of losing quality during storage operations.
Once introduced in the ginning plant, the cotton is subjected to the removal of non-lint-content like trash. Due to the high moisture content the ginning plant will operate inefficiently increasing energy costs and harming the quality of the lint and reducing consequently the economic value of the ginned lint.
Furthermore , the control of the moisture content of cotton during testing is important as the hygroscopic nature of textile material allows for many fiber properties to vary in response to the ambient environment.
Standard ASTM D1776-15 is the recognized guide for conditioning and testing textiles, including cotton fiber. The ASTM standard calls for a temperature of 21 ± 1 °C and 65 ± 2% relative humidity when testing cotton fiber and a relative humidity specification of 65 ± 5 % for testing yarns and fabrics. Some laboratories utilize ISO 139:2005 which calls for a temperature of 21 ± 1 °C and 65 ± 4 % relative humidity considering the measure uncertainties of the probes.
The strength and elongation tests of cotton fiber is subject to change based on moisture content, with other physical measurements subject to a lesser amount of change.
Laboratories for Cotton testing
There is a risk of damage to the fibers even during processing. Standard practice across the textile industry is for bales within a laydown to be opened and allowed to equilibrate prior to being processed.
Proper control of environmental conditions during processing is important to the effective and efficient processing of cotton fiber. As moisture content of cotton lowers the fiber becomes more brittle and subject to damage during processing.
D) DYEING AND FINISHING
Dyeing and FINISHING can ultimately be affected by poor moisture control of the fiber. Color changes due to improper moisture control in seed cotton and ginned lint may still cause shade variation in the final dyed and finished fabric. These color differences may not be noticeable until after dyeing and finishing and lead to claims against suppliers.