The vast majority of guitar fretboards are made of rosewood, ebony, or maple. These are dense woods with different characteristics. Maple fretboards are almost always sealed with a varnish or lacquer coating and require very little care other than cleaning. The sealant coat prevents dirt and grime from getting into the pores of the wood and accumulating. Rosewood and ebony are left untreated and the natural oils in the wood protect them. The cleaning products that can be safely used on maple are unsuited to these woods. The same care that is used for these would apply to other dense natural finish fretboards (unvarnished).The vast majority of guitar fretboards are made of rosewood, ebony, or maple. These are dense woods with different characteristics. Maple fretboards are almost always sealed with a varnish or lacquer coating and require very little care other than cleaning. The sealant coat prevents dirt and grime from getting into the pores of the wood and accumulating. Rosewood and ebony are left untreated and the natural oils in the wood protect them. The cleaning products that can be safely used on maple are unsuited to these woods. The same care that is used for these would apply to other dense natural finish fretboards (unvarnished).