Cleaning concrete and flagstone

[allstar 14]

Does anyone have any recommended cleaning products to clean these? I usually use just cold water pressure washer 3700 honda engine. It usually works well, but trying to make my job easier with a chemical.

[Craig 111]

Wow you've got two very different substrates here. Your question needs to be more specific. What are you trying to clean off? Dirt, oil, grease, gum, oxidation, rust, efflorescence, acid stains, calcium bicarbonate, mineral staining... you get the picture.

also, are they sealed with anything?

What does your customer want to achieve?

[814jeffw 71]

Considering you're talking about everyday dirt and grime, it has been my experience with flagstone that if you apply 6% chlorine to the surface and let dwell for about 5 minutes and then wash away the softened dirt and mildew, you'll achieve nicer results than with just water blasting,...those black and green algae and mildew spots on flagstone are tough to clean without chemical assistance. It may take more than one application to get the desired results, especially if they've never been done properly before. Basically the same thing with concrete, except I use a little caustic soda in with the chlorine because concrete is usually more porous than flagstone and the caustic adds a little extra cleaning power to help soften the dirt and mildew. Then I sometimes apply oxalic acid to the cleaned surface to brighten the concrete up some. If you do a lot of concrete cleaning a surface cleaner is BIG advantage. Oh, by the way, before spraying any chemicals take personal precaution and soak all surrounding ground and vegetation because even a little over spray of chemical will turn leaves brown and possibly kill plants. You are going to have chemical run off the edges during rinsing so make sure you have the dirt pre-soaked before rinsing the surface.

Jeff

[allstar 14]

Thanks for the tip. Sorry about not being more specific. As of right know I just needed help cleaning off mildew spots and black and green algae. What would you use for some of the other stains that you mentioned? They are not sealed with anything and the customer just wants to get them looking clean.

[Richard 17]

Allstar

Go on "Diedrich Technologies", "Eaco Chem" , and the "Prosoco" websites.

You'll find a lot of answers there.