What does Good Middling mean?
The highest grade of cotton as it contains the least amount of foreign matter.
Heddels explains Good Middling
The grading of cotton is determined by its strength, color, staple length, uniformity, smoothness, and micronaire (fineness). In addition, large amounts of leaf and debris will lower the cotton’s value. Grading cotton is a somewhat subjective process; therefore, a cotton’s grade can vary from one grader to another. Middling cotton is considered the median and is used as the standard to measure all other grades of cotton. It is a fleecy cotton with very small amounts of debris and is nearly white. In the United States, good middling cotton (symbolized by GM) is considered the best grade. It contains less foreign matter than average and has a creamy white color.
Here is an example of Good Middling cotton: