Why High Pressure Fails on Indian Sandstone

This episode explains why blasting Indian sandstone with high pressure often leaves lichen roots behind, causing rapid regrowth and unnecessary surface damage. It also breaks down the professional softwash approach: pre-wetting, surfactants for better dwell time, and residual biocides for longer-lasting protection. Show Notes Patio Black Spots: Why They Return & How to Stop Them – SoftWash UK Ltd: https://www.softwashing.uk/blogs/news/patio-black-spots-why-they-return-how-to-stop-them