It is important to have a care routine for your stone or wood sculptures. Just like you would have a humidifier in your home to keep your wood cabinets, trim and furniture from drying out and becoming brittle. I keep a small cup of water inside my curio cabinets.
At least once per month I wipe down my sculptures with "Liquid Gold" furniture polish or a natural "Beeswax" polish. If your sculptures start showing signs of "dry" spots before the end of the month, you might want to start treating them more than once per month.