White substance from concrete on brick?

[SPW Clean 14]

Hi Everyone,

I'm hoping that you can help me with trying to remove a white powder like substance on a brick retaining wall. The client just recently had his concrete driveway done and there is now a white substance on the brick retainer wall where those who laid the concrete used a PW to clean up their job at the end. They blew this white substance, from the sealer I think, all over the retainer wall and they could not remove it with just water. I was thinking of just trying to use concrete sealer remover. Has anyone done this type of job before and if so what worked for you well? Thanks for any help you can provide. The picture of the side stairs shows the white substance that I'm speaking of the best. My pics are not compressing right now. I will try to post them tomorrow.

Thanks,

Keith

[814jeffw 71]

Just wondering how sure you are it's sealer, I may not be following, was it blown on there from the power washing or was it blown on there from the sealer application? People can be boneheads,.. but I find it a little hard to believe that they would have needed to clean up a freshly sealed driveway by water blasting, maybe I'm wrong but wouldn't sealing be the last step of the process. I tend to think if it's sealer it was applied by sprayer and what you're seeing is over spray. Hard to tell from where I'm at though. A little off the subject but,.. Isn't concrete supposed to sit for a while before sealing anyhow? If you determine it is definitely sealer, ask the contractor what sealer was used (brand, and whether it's water based or oil based).

Jeff

[PressurePros 249]

Without seeing the pics I am going to make an educated guess. Its not sealer, its effloresence. When they sealed they probably did have overspray and blasted the brick with high pressure to remove it. That drives water into the brick. When the water leecehes back out it brings soluble salts with it. Thats the powder you see on the surface. Do a search for effloresence (if I'm spelling it right) and you will find the right comapnies that will sell you the right chems to remove it.

Thats why you should always hit brick and stone with low pressure.

[SPW Clean 14]

Just wondering how sure you are it's sealer, I may not be following, was it blown on there from the power washing or was it blown on there from the sealer application? People can be boneheads,.. but I find it a little hard to believe that they would have needed to clean up a freshly sealed driveway by water blasting, maybe I'm wrong but wouldn't sealing be the last step of the process. I tend to think if it's sealer it was applied by sprayer and what you're seeing is over spray. Hard to tell from where I'm at though. A little off the subject but,.. Isn't concrete supposed to sit for a while before sealing anyhow? If you determine it is definitely sealer, ask the contractor what sealer was used (brand, and whether it's water based or oil based).

Jeff

Thanks Jeff, that would make a lot more sense than it being sealer. I have never come across this before so I was describing from the info I got from the customer. I have asked the owner if he knows what they used b/c I believe that he may, he should be getting back to me today.

Keith

[SPW Clean 14]

Without seeing the pics I am going to make an educated guess. Its not sealer, its effloresence. When they sealed they probably did have overspray and blasted the brick with high pressure to remove it. That drives water into the brick. When the water leecehes back out it brings soluble salts with it. Thats the powder you see on the surface. Do a search for effloresence (if I'm spelling it right) and you will find the right comapnies that will sell you the right chems to remove it.

Thats why you should always hit brick and stone with low pressure.

Great observation! :) I will do some tests on it tomorrow and narrow down the possibilities but more than likely you are correct. Is there a safer way to test for effloresence than the acid/fiz test?

thanks,

Keith

[Celeste 341]

| EaCo Chem Inc. Cleaning and Restoration Compound Manufacturer | There are great articles there and they sell the best chems IMO :)

Celeste

[MMI Enterprises 289]

I'm hoping that you can help me with trying to remove a white powder like substance on a brick retaining wall. ........and they could not remove it with just water.

Ken is likely right on..Since it is white then it not actually concrete powder splashed up from rinsing and so there is good chance it is salt effloresence directly from brick, if it is really stuck good, or was leached up out of slab and simply oversprayed to it since it is new concrete curing out. Driving water into surfaces can cause these issues or caustic chemicals can cause it. It is not uncommon to keep water on new concrete or to seal it right away by spreading flakes/powder or spraying liquid acrylics. The process is called curing and moisture is purposely kept in the crete. It gets stronger by slow cure.

Mild hydrochloric acid (muriatic acid) should work and but sodium hydroxide/lye (which is alkaline cleaning component in things like drano, oven cleaner, etc.) could make it worse. Do a small test spot with both. If it just comes off with the hydroxide and doesn't come back after good and dry then the powder could have been just powder sealant.

[SPW Clean 14]

Thank you all for your help! Unfortunately the customer decided to not have this done at this time. Here are some pics of the job.

Keith