Brick Efflorescence or sealer?

I got a request from one of my customers to help clean their brick mailbox kiosk. I thought I was dealng with what looked like efflorescence, but I’m struggling to make any impact on it. I’ve been over there 4-5 times now and tried several things. To start with, I put about a 3% mix of SH on it to get rid of any organics as there was some black mold showing. After that, I pressure washed it and it appeared to remove almost all of it, save a few small white outlines on a couple of the bricks.

The second time I went back, I tried some OneRestore while I had some Efflo on order and used a rotary abrasive pad on my drill which seemed to be removing things. I noticed that it looked like it might be an old coat of sealer so thought using some mechanical persuasion would impact it. Looks great when it’s wet. I went back a couple weeks later - no difference. I went back after about a week and tried some muriatic acid on it, but this had no effect either.

I finally got the F9 Efflo in and went back to apply that, saw some reddish runoff from the bricks and it foamed up so thought I had it. Again, a week later - seems like no difference. I explained to the customer that it looks to me, that it was sealed at some point and that I might be fighting the sealer thinking it was efflorescence. He didn’t know if it was sealed or not - hadn’t done anything since he bought the place about 15 years ago. So, I went and bought some Behr sealer (I’ll admit it was the cheap stuff, but I didn’t charge a lot for this job to begin with and it has become a learning experience at this point) I put the sealer on about two weeks ago - went back today and to me, it doesn’t look like I made any difference at all.

Has anyone any idea what I could try at this point? I am not aware of any type of stripper I could try, but willing to give it a shot. It seems like some of it could be efflorescence and some of it may be sealer. Not sure what direction I should take at this point to make a difference short of sandblasting or convincing him to paint to cover it up. I have some NMD80, but not sure if that will have any effect given Efflo didn’t even change anything.

Any ideas would be great, I really appreciate everyone’s help here and try my best to exhaust any other avenues with past articles - I checked this one, but there is no followup on what the resolution was - Brick Efflorescence

I have had positive results with NMD80 and brick - unfortunately, I think you have sealed your fate with this one (pun intended). I would have strongly recommended not sealing until you were finished with the cleaning.


Thanks Sir - I was afraid of that. I’m going to perhaps try xylene on a small spot to see if it has any effect. I read that if you test a spot with xylene it will be sticky if the sealer was solvent based, otherwise if not sticky, it is water based. I know what I used was water based, but hopefully the xylene will have some affect.

Find a brick expert - a chimney repair guy gave me some helpful secrets a while back.

That’s a great idea! Thanks! I’ll post what I find.

If I had a dollar for every job I should’ve walked away from but did anyway… I’d probably have more money :joy::joy:

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I hear ya. These “learning experiences” disguise themselves as simple and end up costing you an arm and a leg. This customer hired me to wash 40k SF of driveway last year, so it’s almost like I had to say yes. The thing that kills me is the kiosk is just this little dumb structure, but man - it’s throwing me for a loop as to how to get the darn little white streaks off of it. :rofl:

Yea I’ll do just about anything to keep a client I like. A little investment of time and chem on the front end that results in a very positive return the next year is worth it as long as my calendar has room.

Its always the little things that get you lol

Most of what you see on there is not efflo, it’s where someone pointed up the joints and it’s leached out. NMD80 should have been the first thing you did. Not sure why you would seal it. All any sealer does is highlight what’s underneath it. Your owner probably is going to have to liv with it at this stage.


Looks like the mortar from between the bricks is leaking. Since is sealed only if you strip it you can improved by staining it maybe.

I stupidly thought that it was sealer and that it would remelt with another coat. I should have understood more before becoming impatient in hind sight. I’m reading a lot about xylene and hoping that it will help remove a lot of the sealer. (I used water based Behr water-proof with siloxane which apparently can be melted with xylene.) If I can get enough of the sealer off, then perhaps I can get NMD80 to remove the rest and get it looking better.
Thank you for the insight, I learn every day which is why I really love this business! (Now if I could just keep the rest of the body from falling apart! :joy: - thank god I’m a multi-billionaire though - I get email every day telling me it’s waiting for me, I just have to send them my contact information…)

Call Behr’s help line and ask them what to use to strip it off. They’ll know best.

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Thanks @qons - great suggestion. I actually spoke with the folks at Behr and they let me know that they don’t make any stripper, but that siloxane was what was to be removed. The person I spoke with didn’t seem to endorse xylene one way or another. I also spoke with the folks over at Eaco-Chem who were also very helpful. They do make a product called AcrylicStrip which I ended up purchasing from a distributor not far from me. It seemed to work as far as I can tell. After applying, waiting 5 minutes dwell per the instructions, then applying again before it dried and waiting for a 10 minute dwell period, I rinsed and it appears to have stripped the sealant off as in this pic;

After rinsing I tried applying some NMD80 and it was foaming up. (on areas that I hadn’t stripped, it would just run off so it appeared the stripper worked somewhat) I waited for about 10 minutes and kept it wet - I reapplied again to heavy spots and it foamed up again and then waited another 10 and rinsed. Unfortunately, until the brick has had a chance to dry for at least several hours, it’s difficult to see if it worked or not. I’ll shoot over there again tomorrow morning (unless hurricane Nicole speeds up) and see what the results are. I was able to apply NMD80 to the structure after rinsing and waiting a few minutes as the winds were picking up around 3. I’m hoping that I will be left with some spot cleaning of some of the areas, but it’s difficult to tell at this point. (I circled some of the spots that I kept retreating)

The brick which has been stripped does look different though - it appears dryer than the non-stripped brick. I’m interested to see if the areas that were hazy change.

The leaching white streaks are not soft and don’t seem to soften when NMD80 is applied. They are more hard deposits which I didn’t understand. I can definitely see them reducing in size/width after each application of NMD80, but not what I thought it was going to be - I imagined more of a complete instant removal which doesn’t appear to be the case - at least with this.

Here is a before and after pic of one of the leach lines to illustrate what I mean;



I think I’m making progress though, it’s just not how I expected it to react to the chemicals. It’s a little tedious with the dwell times and the progress is subtle, but there.

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You’ve made a good learning experience out of this, good for you. The nmd80 is designed to remove excess mortar tags and white haze left on brick or pavers, in other words, any excess mortar and in some cases will remove some efflo. You’ll also learn that in some cases, no matter what you do, you can’t get rid of it and in others it can be as simple as spraying a little F9 Efflo on and rinsing. You never know, so good reason to always set realistic expectations with clients. The more you do the more you’ll recognize what’s possible and best approach or order of events to proceed. Again kudos for the effort and persistence.


Every experience can either be good or bad just depending on your viewpoint. As @Racer said it is a good learning experience. While you might feel that you have wasted a lot of time, what you’ve actually done is pretty much mastered this kind of problem, which will give you ammunition to tackle a larger problem of the same kind in the future. One of the great things about this little project is that it is a small area. Imagine if you were trying to do this on a 40,000 square-foot driveway and all of the various methods you tried ended up just discoloring a section of it (I know you may not have discolored it, but when we go into things blind it’s always a possibility).

Regarding using new sealer to melt old sealer, that is a thing, except I’m not sure that water-based sealer, even with the chemical in it that was supposed to melt the old sealer, would be strong enough. I do not do sealing personally, but I work with a 30 year Tile and Stone restoration vet who has taken me under his wing, and teaches me various aspects of that side of the business as I go. I had a job 2 years ago that I needed to remove solvent based sealer from 6000 ft.² of Sotero tile. I told him that I was able to get most of it off, but there was some areas that were being really stubborn. (it was a couple years old and failing). I saved the client a lot of money from doing a chemical removal by being able to get most of it off using high heat, high pressure and 15° tip at 1 inch away from the surface. $1/sf was about half of what I should of charged lol. It took five 8 hour days. He educated me that if you use a really hot solvent-based sealer, it could emulsify with the sealer underneath it, and make the white go away. In that case it did work, but he gets high end products from out of California that last a lot longer.

Regarding what was on there, it could’ve been sealer or efflorescence from the thin set in the mortar. There is four mailboxes there so there’s a chance one of the neighbors had it sealed at one point and never told him. But no sealer will last 15 years, especially in the sun. If it were me, I would’ve first tried efflo (undiluted). If that didn’t work turbo nozzle on high heat. And then, after that, I would’ve have resorted to sanding it off. The problem with trying to remove sealers now is that the chemical MEK is no longer readily available due to a change in laws. (however, there is a product at top plastics that has MEK in it but it is a small bottle like the size of a tube of toothpaste, for like $12.) That may have worked in this situation where you had small, isolated areas.

It is refreshing to see such a thorough post from start to finish with follow up. You did well and I think anyone reading this post will benefit from your experience. Thank you for sharing!


I’m with Racer, good job! You really turned this project around. Another thing to keep in mind, is that moisture often is what forces the minerals and other impurities out of the brick. Sometimes timing comes into play when bidding these projects, especially if you’re in a humid area.

Thanks for the kudos and replies guys - I appreciate it. I caught whatever bug is going around and have been out of pocket for a while with fever and coughing. I need to get back over to this kiosk to see how things look after a few days (it’s also been raining here a lot lately which makes it hard to see)

@seandz - I did try F9 Efflo but it seemed to have 0 effect as well as a turbo nozzle…

This mail kiosk customer also has a cooking grease stain at his house that I’ve thrown everything at but it won’t budge. I’ll post that under a separate thread after I complete looking for solutions and share what I find or ask y’all’s opinions.

Thanks again everyone!

Just a point in fact, be careful using a turbo nozzle, because the pressure with the water will cause even more efflo. Kind of like fracking for oil, lol except you’re fracking for efflo.


Thank you - that’s good advice. I initially used it to remove some of the moss that was growing on the kiosk and try to take it easy to not damage anything.
I thought it was quite the miracle tool at first, and it has its place. However after learning from you and others, I found that SH and the high pressure jrod nozzle does as good of a job at removing organics, is gentler and actually turns out to be quicker. Thanks again Rick.

One thing I really like to use is a size 20 tip for 8gpm machine. I found that 700-1000 psi is pretty amazing at getting just enough pressure to remove stubborn stuff but not cause damage on a lot of somewhat stronger surfaces.