-This is for keeping the strings to your instrument, clean and protected.
Apply a little quantity on the fretboard, frets and strings, wait a minute or two, then carefully remove it with a cloth. The string cleaner will do its job, plus, it will also leave a subtle patina, which will protect the fretboard and the strings for a while.
Don't use too much of this, it's a great product but you need to use it sparingly. Just clean your strings with a cloth after you've played and they will stay fresh longer.
For those who have been using Fast Fret for a while, you might have noticed that, nowadays, the produce smells differently. This is because the new recipe contains petroleum. Nothing to worry about, just follow the guidelines and you'll be ok.
The rule of thumb is: use it sparingly, but regularly, every time you fingers start getting stuck on the fretboard, and using a clean cloth alone doesn't make a difference, apply a little dose. Timing depends on how much you play. For me, I use it once every ten days or so.
If you do this correctly, the cloth you use shouldn't get dirty.