by hirokinakamura » Fri Dec 06, 2013 8:23 pm
quality of cotton is measured by a couple main things: the staple (the length of the fibres), the colour, the purity, the fibre strength and the uniformity.
For your question, sea island cotton is a specific type of ELS (extra-long staple) cotton. ELS cottons are the highest quality cottons like pima and egyptian. To be considered ELS, the cotton fibres have to be at least 1 3/8" long but the highest quality ELS cottons (like sea island) will have staples around 1.5-2.5" in length. Sea island cotton is grown on the sea islands (hence the name, obviously), which are off the coast of Georgia and South Carolina. Production is limited because of limited growing space and because ELS cotton is the most labour intensive type of cotton that is grown. This is why Sea Island cotton products are so expensive.
There's Pima cotton, which is the general trademark name under which American ELS cottons are sold. The name comes from Pima Indians, who were centered in Arizona, they were involved in the southwestern cotton business, which is were most Pima cotton is grown today. There's Egyptian cotton, which is very well known and synonymous with luxury. Most Egyptian cotton is actually not ELS but just long staple (still good but not the best) cotton known as Giza 86. Additionally, people have been abusing the Egyptian cotton label to churn out substandard very un-luxury cottons, which just undermines and waters down the Egyptian cotton label.
There are so many different kinds of cotton that you can't really look for specific things in terms of texture and feel to determine quality. These types of things depend on not only what type of cotton it is, but how the cotton is grown, where the cotton grown, how the cotton is processed (how much it is spun etc...). You can have high quality cottons that are silky smooth and high quality cotton that are irregular and rougher (like those you'll find in japanese denim or vintage-type repro t-shirts).
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