Got a call from a guy who said he had someone out to polish some limestone, and said it was looking terrible and turning yellow. I skse, “did he use a spray bottle” he said yes and I told him I thought it might be that he used “crystallization” and it has trapped moisture in the stone, etc.   Need to support my claims. My word against this other guy at this time.

Found Freds classic article on his blog.  Any other suggestions?