I’ve been using Fast-Frets by GHS for a long time now. An old worship leader friend of mine introduced me to the stuff probably 24 years ago (sheesh!).
What do I do with it? I wipe my acoustic guitar strings down with the stuff pretty much every time I play.
What is it, exactly? Here’s what Musicians Friend says about Fast-Frets:
GHS Fast-Fret String Cleaner cleans your musical instrument strings, brightens your sound, and prolongs fingerboard life while letting you play faster than you ever imagined! Convenient applicator and cloth. For all stringed instruments.
Why do I use it? Because it makes my strings sound brighter, just like the blurb above says. Yes, it probably cleans the strings and keeps the fretboard happy too. But I don’t really notice that stuff – what I DO notice is the difference in sound after using it.
image by LeoL30