How to verbs flagstone and slate? Does anyone have any tips for cleaning years of dirt from outdoor...

Does anyone have any tips for cleaning years of dirt from outdoor flagstone and/or slate ? I've see it suggested that a pressure washer is a good concept, however, I'm not sure if that alone would be effective.
Answers:    You can alertly use miractic acid to verbs the stones. Use rubber gloves and protective eyewear. Pour some on the stones and use a broom to perform a scrub action. Then rinse near water.
I would thieve the pressure washer approach with the complement of a SAFE chemical! I have have great success next to a product called TSP. You may purchase it at a painter supply like Sherwin Williams. It is a combination of trisodium phosphate. It is a great House and deck cleaner and be used quite extensively surrounded by household detergents until EPA cracked down on the harmful effects of phosphate on the environment. Mix as directed next to household bleach and you have an extremely successful cleaner that not only releases years of grime but also kill mold and mildew. Apply with a pump up sprayer and permit set 5 min.( do not let dry) and next begin the pressure wash.This will not hurt your landscaping similar to an acid will. You do stipulation to rinse all plants by spraying them beside clean river. Be careful near the mortar joints as the pressure washer can dislodge elderly joints. You will be amazed at how verbs your patio become
Take Care and best of luck,
Phillip