welcome to GoY.

Is what safe to use on sandstone?

Well, let me take a couple of guesses....
A vinegar cleaning solution, is it safe to use on sandstone patio tiles?
Answer is yes.
A power washer, is it safe to use on sandstone patio tiles?
Answer is yes if not used at full force pressure.
Just let me know Phil by placing your response in the answer section located below your question.