1. How they are made.
Cotton grows on a plant, and it takes many steps to prepare it before becoming cloth. Cotton grows as balls of fiber, or lint that must first be picked. Once it’s picked, the cotton fiber has to go through a separation process called ginning to pull the lint from the seed. It’s then put into bales that are sent to a textile mill and spun into yarn to create fabric.i
Polyester is an artificial man-made fiber which is manufactured from petroleum. There are three primary steps in creating polyester.ii The first is condensation polymerization, which is a process of heating acid and alcohol to high temperatures in a vacuum causing a reaction called polymerization. After polymerization occurs, the material hardens and is cut into chips. The second step of the process melts the chips that are then pushed through spinnerets. The materials cools as it hits the air and it is wound around cylinders. Finally, the fibers that were formed are again heated and stretched to about five times their original length. The material is now ready to be used to create fabric.iii
2. The cost for the material.
The prices of cotton versus polyester depends upon many things and they are affected by different market forces. Since cotton is a plant, it is traded as a commodity future, whereas polyester relies on the availability and price of petroleum, which can a much more volatile market. While their prices remained relatively close to one another throughout the early 2000s, a huge increase in the price of oil in 2011 caused the cost of polyester to jump significantly.iv However, it is still generally less expensive than cotton.
3. Their ability to biodegrade.
Another major difference between cotton and polyester is their ability to biodegrade after the fabric has passed its useful life. Since cotton is a naturally occurring biological material and polyester is synthesized, it makes sense that cotton would biodegrade much more quickly. Large-scale compost and laboratory testing on both materials has shown that cotton degrades relatively quickly, whereas, polyester shows a slight initial degradation, but then typically remains intact.v
4. Their traits.
Cotton and polyester are both desirable materials with specific strengths. Some of the desirable qualities of cotton include that it is cool when worn (breathable), it is very absorbent and dries slowly, it is soft and drapes easily and it can be washed and ironed, which is good because it wrinkles easily. Products that highlight these qualities well include towels, T-shirts and jeans.vi Polyester is non-absorbent and dries quickly, is very durable and is crease resistant. It is easy to care for and like cotton, it is also soft and drapes easily. Common uses for polyester include raincoats, fleece jackets, children’s pajamas, medical textiles and work clothes.vii
5. How they blend with other fabrics.
At times, it may be desirable to blend either cotton or polyester with other fabrics to enhance a certain characteristic, such as breathability, strength or the ability to stretch. Some of the fibers that cotton mixes well with include linen, polyester, elastane (spandex/ lycra), and viscose. Examples of common polyester blends include wool and cotton.viii Each of these blends will feature some characteristics of each material and create a unique type of fabric. However, one of the most common blends is that of cotton and polyester themselves. There are a number of reasons for this related to price, performance, maintenance and the ability to hold color. Adding polyester can make the material cheaper, allow it to dry quicker and resist sweat. Also, polyester doesn’t shrink as much as cotton and it generally holds color longer than cotton.ix All of these characteristics taken together lead to a cotton/polyester blend being a very desirable type of cloth.
6. Their ability to be consistent.
Since cotton is a natural fiber, there are a great many variations in its properties. Cotton bales typically have a Spinning Consistency Index in order to calculate and predict its overall quality and spinnability.x Despite this, the natural variations within the plant itself will lead to variances in the final output and may include blemishes. Since polyester is a man-made material it is much easier to create the conditions that will produce consistent, identical, blemish-free material every time it is produced.
7. Consumer preferences.
Consumers today have a strong preference for something that is natural and therefore, have a strong leaning towards cotton being preferable. Nearly 8 in 10 consumers say they would prefer their clothing to be made from cotton or cotton blends as opposed to synthetic clothing.xi Consumers overwhelmingly believe that cotton is more comfortable, sustainable, trustworthy, soft, authentic and reliable when compared to polyester and the majority said they would be bothered to find retailers substituting synthetic fibers for cotton in their clothing. This is even true when asked if they were willing to pay more for cotton clothing. Well over half of the consumers in one study indicated that they would pay more for cotton.xii