Micro fiber threads are typically made from a conjugated blend of polyester and polyamide, the latter being a textured nylon. In order for the fabric to be classified as a micro fiber, each conjugated thread needs to be less than one denier in size. This is equivalent to at least 1/6th the diameter of a typical human hair.
Each circular thread then undergoes a special process that adds slits around its circumference. This creates polyester filaments which are typically 100 times finer than human hair which are bonded to a polyamide core. The polyamide nylon core is hydrophilic, which means that it has a special chemical affinity to water. The polyester filaments are lyophilic, and attract oils, dirt and grime which will bond directly between the filaments and fiber threads until washed out.
Cotton towels mostly absorb and hold moisture between the threads. By contrast, micro fiber towels absorb moisture not only between the threads, but also within each thread. On a weight per weight basis, this makes microfiber far more absorptive than cotton fabric. Hence, a microfiber towel is far more compact and lightweight compared to a cotton terry towel with the same absorption capacity.
Further, as micro fiber is fabricated from inorganic synthetic materials, it does not encourage bacterial growth in the same way that a cotton towel will do if left damp for an extended period. For travelers or sports people who need to pack their towel back into a bag immediately after use, this is a distinct advantage.
