It's a controversial topic, adding moisture to cotton during the ginning process. But Bill Mayfield makes no bones about his position on the subject.
“I personally believe in moisture restoration back to the 7 percent range,” he told members of the Southern Cotton Ginners Association at their recent annual meeting.
“There's potential in the ginning process to put some added moisture in many bales that are only in the 4 percent to 6 percent range, says the former USDA Extension cotton specialist, now a consultant for the SCGA.
Adding moisture to bring cotton up to the ideal 7 percent range is “not illegal, not immoral, not dishonest. The textile manufacturers pay for most of it, so the question boils down to whether the grower's going to get the money for the added weight, or whether the merchant's going to get it.”
A study has shown that almost all moisture restoration methods being used by cotton gins “put in less moisture than most folks think,” says Mayfield.
Most commonly-used moisture measuring devices read high by 1 percent to 2 percent, he says. “You may think you're turning out a bale with 6 percent to 6.5 percent moisture, when it's actually only 5 percent to 5.5 percent.”
He points to a considerable amount of research, going as far back as the 1950s, to determine the effects of various moisture levels. Data from those studies show that cotton stored at high moisture levels, greater than 8 percent, will develop mold and undergo unwanted color changes, he says. “There has also, unfortunately, been a lot of misinformation about moisture restoration, even in cotton publications.”
It has been established, he says, that there is a need for a 7 percent moisture level at the gin press. “In a perfect world, every bale would leave the gin at 7 percent. The absolute maximum is 8 percent.”
Cotton in storage will move toward equilibration with the moisture in the air, he notes. This will happen faster or slower, depending on the type of bagging on the bale.
“The average humidity during warehouse storage for a typical Mid-South cotton bale from Dec. 1 to Apr. 1 is 60 percent to 80 percent, with an average of 70 percent,” Mayfield says.
“If the bale is at 5 percent moisture going into storage, depending on compression, it will pick up moisture from the atmosphere until it reaches equilibration.
“Ginning isn't a perfect process, and moisture measurement isn't a perfect process,” Mayfield says. Keys to effective moisture restoration are accurate measurement of moisture already in the cotton and precise control of devices used to add moisture.
Moisture restoration at the gin press reduces stress on the press and reduces the hydraulic pressure and energy requirements for the press, he says.
“It's very important to understand that moisture restoration absolutely will not improve fiber quality. Articles that have appeared in some magazines to that effect are completely bogus. A decision on whether or not to add moisture should NOT be made on the basis of improving quality — because it won't happen.”