Wood dries out over time and the natural oils evaporate. If these oils are not replaced, wood can become dry and brittle and absorbs moisture through the air. Moisture will expand dry wood, and, over a period of time, this shrinking and expanding may cause cracks and checks on the wood surface and can loosen glue furniture joints. Beautify. Commonly used to enhance the beauty of the wood by cleaning the surface finish, raising the shine and giving the wood a deeper, richer look. Protect. Used to moisturize the finish and prevent cracks which can arise from excessive heat or dryness. Polishes have a low surface tension that gives scratch resistance and protection from common wear and tear. In addition, they leave a low molecular film adding protection against spills.