Porous stone sculptures are highly susceptible to surface degradation due to their absorbent nature, which makes them vulnerable to moisture, pollutants, and biological growth. To preserve their integrity, several effective methods can be employed.

1. Regular Cleaning: Use pH-neutral cleaners and soft brushes to remove dirt and debris without damaging the stone. Avoid harsh chemicals that can accelerate erosion.

2. Protective Sealants: Apply breathable, penetrating sealants designed for porous stone. These create a barrier against moisture and contaminants while allowing the stone to "breathe."

3. Environmental Control: Minimize exposure to extreme weather by placing sculptures indoors or under protective coverings. Maintain stable humidity levels to prevent cracking.

4. Biological Growth Prevention: Treat surfaces with anti-microbial solutions to inhibit algae, moss, and lichen growth, which can cause discoloration and erosion.

5. Professional Restoration: For severely degraded sculptures, consult conservation experts who can perform specialized treatments like consolidation or poulticing.

By combining these methods, you can significantly extend the lifespan of porous stone sculptures while preserving their aesthetic and historical value.