Right after.Stone will get just like new over next few weeks.
Right after.Still wet.Stone will get like new over the next few weeks.
Before and After
Before pic.Second pic right after.Big pic a week later dried.This stone was covered with lichen and algae.For heavily covered stones with algae,lichen.moss,etc I recommend two treatments a month apart to keep them biological growth free up to a year.
Right after.1 treatment is all that's needed for this stone. It will keep on self cleaning up to a year.