Those of you post treating: I downstreamed some HW after my final rinse. End result as I was done was it looked like a driveway full of a light white foam. Does it dry clear?
yes and keeps brightening. problem is, you might have soap sediment that dries on the concrete. Goes away after a rain or two. I use my ball valve to soap. Wide open and there is little foam.
Ah, gotcha. I'll try to snap a pic of one little area of soap sediment from a cleaning I did the other day. Oddly, it's the only spot with sediment and nobody's said anything. I have a ball valve on the way, should be here middle of the week.
Thanks for your reply, Ralph.
Is a pretreat with a 20% mix strong enough for dirty sidewalks?
I would say it depends. What kind of dirt are we talking about? Dirt and grime? Stains from fertilizer? Some don't pretreat at all, just blast it with a surface cleaner.
Why not try pretreating half the sidewalk and just pressure wash the other half? I don't think there would be much difference IMHO.
Pretty much just black algae. My ds comes out as a 20% solution.
You'll find some guys swear by pretreatment. Others say you just need to pre-wet surface with water. Then there's others that say no pretreatment is needed, just start cleaning.
Do a YouTube search for how to pressure wash a driveway. Lots of opinions and in the end they all end up with a clean surface.
Miquel when you are cleaning driveways its like fighting a giant.You need all the tools you can get because the driveway has usually been neglected for years.When you pretreat it will make surface cleaning alot easier.Alot a times the guys will talk about leaving lines an etc that can be eliminated most times by pretreating with a strong mix of chemicals.
Not to mention,.every job can be different,..some I can treat with a house wash mix DS'ed,..others I lay on roof mix,...and when I run into the "big green" dots of mold,..I put on 12.5%,..these type spots are on sidewalks more than driveways in my experience. But then,..we have predominately asphalt driveways here.
Flagstone patios and walkways are the hardest thing to clean,..it takes multiple applications of 12.5% and NAOH to get the spots completely out. The first round removes the green top of the mold,..leaving behind a black spot,..then it has to be treated and let dwell forever it seems,Ha,Ha,..
As many do,..I pre-treat concrete before I even start the house wash or roof clean,.or deck or whatever,..gives it plenty of time to work,..
Always a good idea to put safety cones up anywhere that's been treated as to avoid foot traffic in and out of the house. Usually isn't an issue. But sometimes the mailman shows up or UPS,..nice to keep them out of the 12.5% if possible and walking through the grass.
Pretreated with downstream house wash mix, 20 minute dwell time, cleaned with cold water.