Butcher Block countertops are made of the finest hardwoods, hand selected and kiln dried to a moisture content of 6%, making them very susceptible to water and dampness. Extremes of humidity and dryness can swell and shrink tops enough to cause small seasonal checks to appear. This is an unavoidable condition of enjoying the character and beauty of a product made from a natural material. You can help preserve your butcher block by keeping your home properly humidified and by refreshing it with oil on a regular basis. If cracks do appear, they can be filled with a cellulose filler of the correct tint and become practically invisible.