We will be cleaning 13,000 sq. ft. of concrete walkways next month and I'd love to talk to someone who knows about brightening concrete with acids after cleaning. I've been using a product over the last few years that works very well, but it's just not cost effective. Any help would be appreciated!
Not my area of expertise. However its like using rubbing compound on a car. Strip away the old oxidized paint and reveal the newer coat. Acid and pressure is actually good for restoration work!
I have used a flat surface cleaner and acid wash a few times. On washed gravel I have not noticed very much difference but on smooth concrete it does make a difference. I actually discovered this kinda by accident. I was removing a rust stain and you could see where I had applied the acid as opposed to jus the flat surface cleaner. ended up having to spray the accid on the rest of that area so that it would match. If it weren't for the acid area I would of left it without the same. There wasn't enogh of a difference to justify the added time and expense but since I had a CLEANER spot I needed to make the rest match.
You can take 1 gallon of F9 BARCand mix into 2 gals of water... Lightly spray it on and leave it to dry. You should be able to get 1500' minimum per gallon this way (using 3 gals of cleaner).
Or oxalic will work sometimes too depending on what you are removing in order to brighten the concrete.
Do not use HCL to brighten concrete or you'll have etched cement and could ruin your day... and week.