I own a house built in 1935 that has stone exterior. A prior owner painted the stone. I want to remove the paint. Sand/baking soda blasting is cost prohibitive. Tried chemicals but too messy & fear too dangerous, lethal. I tried a heat gun and it seemed to work. Question: will a heat gun ruin the stone or masonry? It is large gray stones, all different shapes, sizes. Any other alternatives not mentioned?