As you progress towards becoming an advanced guitarist, you may start to notice build-up around the frets as well as a dry and sometimes tacky feeling fretboard (depending on the size of your frets.) This accumulation can affect playability especially when bending and holding vibrato. It can also lead to serious drying out of your fingerboard eventually creating irreparable chips and cracks.
Many misconceptions lead people to believe that all products with a high percentage of lemon oil will help seal the guitars wood. This can’t be further from the truth as these products can actually damage your guitar even further. Properly cleaning your frets and fingerboard is important because it helps restore the vital oils needed for the wood to breathe as well as maintaining an optimum playing surface.
When you are in the process of purchasing a sealant for your fretboard you may come across products labelled "100% lemon oil" however, this is more a brilliant form of false advertisement than the truth. If you were to look closer at the ingredients you would find these products also contain many other chemicals, one example being silicone and another being heavy waxes.
You can buy concentrated lemon oil but it contains a high percentage of de-limonene which can be used to lift some industrial glues and can easily ruin your binding and markings. Like with most other products, it’s always best to use something that was specifically created for the task at hand, such as fretboard cleaning wipes. They can be trusted to do their job and not damage your expensive investment. Barring that, mineral oil found in high quality furniture application products can also be used but you have to be more careful about its ingredients.
Whatever you do though, do not use your everyday household cleaners – many contain heavy waxes that might make your fretboard shine for a bit but they will ultimately cause more dirt to accumulate and even cause damage. A common example of these offenders is Lemon Pledge.
Once you have found a product with mineral oil that contains no silicon, no wax and has as minimal chemicals as possible, you can begin the process of cleaning your fretboard. Start by taking off your strings carefully without scratching your finish. If you have wire cutters then cut your strings at the twelfth fret after loosening them from your tuning pegs. Be sure to completely remove the strings from your workplace because used strings once cut are often very sharp which can damage the finish of your guitar.
As a general rule, maple fingerboards usually need very little cleaning due to the lacquer applied in the factory enabling a strong barrier against grime and humidity. Rosewood and Ebony boards most certainly require oil applications once a year because these are untreated woods, but it can vary depending on how much you play. I believe using a plastic credit card along with a toothpick is the best tool to scrape gunk from where the frets meet the fingerboard. This is because plastic tends to be the softest tool against wood which is essential especially when dealing with an important area of your guitar.
The toothpick is handy because it's not going to damage your fingerboard and you have similar precision of a metal blade without the chance of damages. Be very slow and cautious; never rush any type of work with your guitar.
When dealing with fret cleaning, you can simply mask off the wood around each fret up your fingerboard using painters tape exposing only the metal fret and non of the wood. Make sure to tape off your magnetic pickups as they tend to attract metal shavings from the steel wool. Using light steel wool (000 grade) will delicately remove any grime on the surface of the frets. Once this is finished you can remove the tape and carefully blows off the surface of the fretboard. Next you can apply your oil. Dip a fine cloth or old t-shirt in your preferred oil and use as sparingly as possible with just the smallest of shine to your board. If you happen to apply too much, do not under any circumstance, use water on an untreated fingerboard such as Rosewood or Ebony but instead wipe off the excess and you should be fine. Restring your guitar to the desired tuning and intonation using an electronic tuner and you are on your way again.
Educating yourself on caring for your instrument is just as vital as learning how the instrument plays. With just a few simple steps and procedures you will largely improve both your instruments sound and ensuring a long life for your guitar.