Solid wood is a living, breathing material. Throughout its lifetime solid wood will absorb and expel moisture and humidity. In the warmer months wood may swell as it gains moisture and in the cooler months it may shrink as it loses moisture. For this reason it is ideal to keep humidity levels in your home between 35%-55%.
The best way to clean your solid wood pieces is with a damp cloth followed by a dry cloth, making sure to remove all excess moisture. If necessary, a mild soap may be used on a solid surface, however you should refrain from using any chemical cleaners or solvents as they may damage the finish of the piece.