I was just asked to address staining on Indiana Buff limestone. These are exterior panels and have been up for 3 weeks. However, before instalation they sat outside in crates for a month. The stain looks like moisture to me however I'm not sure if the packing materials could have transferred into the stone some? I was thinking about testing a panel with a poultice tomorrow. I also think that finally having warmer spring like temperatures may dry these panels out. The panels are honed.......possibly around 400 grit finish. Pretty smooth. I will also mention that the installer tried power washing and failed. Thanks for your input.

Ron Moore
American Stone Care, Inc.