Guitar strings are one of the most important aspects of a guitar's sound. As such, several different brands and types of guitar strings are on the market. The vast majority of these strings are uncoated strings. This means that the strings have no protective coating that protects the string from dirt buildup. Some string manufacturers do, however, offer coated guitar strings. These strings are in some ways quite different than their uncoated counterparts.
The main advantage that coated strings have over uncoated strings is the tonal lifespan of the string. Over time (within a month for often-played guitars), an uncoated set of strings builds up a layer of dirt and grime that negatively affects the tone of the strings. The layer of coating on coated strings prevents this grime buildup for a significant period of time -- some manufacturers claim up to five times as long -- thus increasing the tonal lifespan of these strings.
The major drawback of coated strings is their price. Coated strings often cost about two to three times as much as uncoated guitar strings. Despite the higher price, the increased tonal lifespan of these strings make them popular with a wide variety of guitarists. In many cases, guitarists actually save money over the long term by buying coated guitar strings. Luckily for the coated-string enthusiast, the price of coated strings has been coming down over the last decade or so.
Most coated strings feel slightly different to the touch than uncoated strings. Some brands almost feel like nylon strings when they are first put on a guitar. Some feel almost slippery. Despite these differences in feel, coated strings respond exactly like uncoated strings. They can be bent and otherwise manipulated in the same manner and with the same ease as uncoated strings of similar gauge. After a few sessions playing a guitar with coated strings, you likely won't even notice a difference.
Brand Name Coated Strings
Many different guitar string manufacturers offer coated strings. Elixir is perhaps the most famous coated string brand name. Their signature nanoweb coating helped to bring about the popularity of coated guitar strings. Other major manufacturers, such as Ernie Ball, Fender, Cleartone, GHS and D'addario, all offer coated guitar strings in addition to their non-coated strings. The majority of these companies offer coated strings for both electric and acoustic guitars.