White spots on stamped concrete after winter

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  #1  
Old 04-13-15, 08:25 AM
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White spots on stamped concrete after winter

I've tried searching for my exact issue, along with other information, but can't really find a suitable match.

Last fall, I re-sealed my then two year old stamped concrete patio using a water based sealer (Anvil Ultraseal 1330, per Anvil's suggestion); I used this after a lot of searching, since I was unable to find out which sealer was originally replied because the company was sold to another individual. I re-sealed doing the following:
  • Power washed the entire patio
  • Used Simple Green degreaser and scrubbed the entire patio
  • Waited an entire week, which was completely dry and in the 70s-80s
  • Sealed the patio using the above sealer in three light coats (with a roller brush), allowing the proper drying time in between coats

Initially, the results looked okay. I noticed some spots were a little darker than others, but figured that would resolve itself in time. Fast forward a few months to winter, which was pretty bad this year (East PA). I started noticing white spots all over the patio, which I assumed was moisture. Now that the snow is gone, the patio looks horrible. There are white spots everywhere.

At this point, I have no idea where to start. Should I be stripping off the old water based sealer and then resealing with something else? How, and which sealer? Some sites say I can just power wash the old water based sealer off, and then reseal with water or acrylic based sealers. Others say I need to use a chemical stripper first to get everything off the surface.

Any chance somebody can provide some in-depth advice on what I should be doing here? I can take pictures when I get home if that'd help, and thanks in advance.
 
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  #2  
Old 04-13-15, 08:39 AM
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Have you looked closely at the spots. Are they on top of the sealer? My first guess would be salt or other mineral deposit left behind by the melting snow.
 
  #3  
Old 04-13-15, 10:17 AM
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sounds more like moisture under the sealer,,, did you use a breathable sealer ? wtr-based sealers are much lower in performance than solvent-based
 
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Old 04-14-15, 12:38 AM
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Still waiting for the pix.
 
  #5  
Old 04-15-15, 08:31 AM
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Sorry for the delay, the past two days have been crazy over here and I haven't had time to do much. I'll grab some photos of the spots after work today. They do appear to be under the sealer (also, I don't shovel or throw salt on the patio at all).

I have no idea if the water-based sealer that I used is considered to be "good", or how well it breathes. I would have liked to use a solvent-based sealer, but since I had no idea which was used when it was originally sealed, I was told the safest route was to go water-based.
 
  #6  
Old 04-16-15, 04:40 AM
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Here are some shots of the patio. The first picture shows the worst of the damage, where the top layer is flaking and peeling off in large strips.









Let's assume that I wind up power washing the entire patio to remove everything and start anew. Is there a recommended sealer to use? There's so much out there to choose from that it's mindboggling. I don't mind paying for a quality sealer if I get the desired results, but I have no idea where to start.
 
  #7  
Old 04-16-15, 04:41 AM
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i'm thinking lack of air in the conc
 
  #8  
Old 04-16-15, 08:16 AM
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I don't see any large strips, but rather random spots of localized scaling. If that's indeed what's happening, I suspect that simply applying more sealer will only slow down the process, but not eliminate it. The scaling will continue to get worse over time. The causes could be attributed to lack of air entrainment, but such is usually more visible as cracking, and over larger areas.
 
  #9  
Old 04-17-15, 02:54 PM
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Here's a better shot of the damage:



I just had a concrete guy over for an estimate. He basically said that there was delamination of the release agent and sealer. He would need to use xylene on the entire patio, then color the top layer to repair some of the areas that are bare concrete (keep in mind that the color was mixed in with the concrete on this patio, it's not just a top coat). Afterwards, he'd seal it with a solvent based sealer. He said it'd be expensive because it was at least 6-8 total days of work in all; won't know what he charges until next week, but my conservative guess is $1500+.
 
  #10  
Old 04-17-15, 07:51 PM
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And exactly what is he going to do that you couldn't do yourself? Although you never mentioned how large the patio is, I'm guessing the materials needed shouldn't cost more than $300 or $400 (unless he's using extremely expensive Unobtainium). Meaning you will be paying him at least a thousand bucks just to broom stuff around for a few days. And I'd expect his work will involve only partial days, vs. a full 8 or 10 hours per day for him and his grunts (allowing for drying time between phases).

Have you asked him if his work is guaranteed, and how many similar jobs he's done in the area? It would be good if you could go and look at a few of them, to get a better feel for what you can expect after he's done and gone.

And I take back my earlier suggestion that the patio was experiencing simple scaling. I only said that because I didn't know that the concrete dye used was mixed in the fluid concrete at time of placement, and not just applied to the surface. I thought the white spots were original, un-dyed concrete showing through after the top had chipped off in those areas. White spots in brown concrete suggest that a chemical reaction of some sort is taking place. Let's wait to hear what stadry has to say about it, as he's a lot more familiar with this type of work.
 
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Old 04-18-15, 02:58 AM
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possible but unlikely a reaction 'tween release agent & sealer (release is just color pigment & finer grind white cement ),,, all similar issues i've seen have been due to conc's lack of air content for cold climes OR wtr vapor coming UP thru the slab then freezing as popouts IF the slab was placed w/integral color ( from the plant ), where are all the white spots coming from ? that looks like normal color conc,,, could be wrong, of course, but i doubt it,,, plants dislike mixing color into a truck load as its extremely difficult ( more expensive ) to wash out the drum when finished,,, IF there are 2 loads or more rqd, color match is impossible & suppliers don't like that liability,,, wanna rethink the integral color part ?

bdge's point about experience, similar work, guarantee, etc are VERY valid,,, mtls won't be expensive BUT you're buying performance & experience - not labor by the day/hr,,, my guys work based on the item - not whether they get 8hrs as some days are 6 & others 10,,, you can squeegee on mtls according to label directions just as easily as any other inexperienced h/o-diy'er,,, i don't have my guys applying sealer til they're mixed & helped for 6mos,,, i dislike punch lists but HATE callbacks
 
  #12  
Old 04-18-15, 04:43 AM
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The issue for me is that I'm not sure exactly what I should be doing here, or what exact materials to use (namely the sealer, since the last one I picked out was garbage). I've read that Xylene works fast and that it's a lot easier with multiple people, so me doing it by myself concerns me.

He said most of the white spots were from a bad chemical reaction between the old sealer and new. He has done a lot of jobs in the area (we even had him come out for an estimate on pouring the patio, but went with someone else), so it'd be easy to look at his work. I just have a feeling that the price he's going to give me will be gouging, because he made multiple comments about not using him initially. That's enough of a red flag for me to not hire him, but I still want to see the number he comes in at.

I'm positive that the color was mixed in and not just top coated - I watched most of the process in person since I was working from home those days. Also, pardon the ignorance, but what does MTLS stand for?
 
  #13  
Old 04-18-15, 07:25 AM
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Mountain Time Latter-day Saints? Making That Little Stuff? Men Talk Like Squids? I'm not really sure.

You'd have to ask stadry, as he has spent considerable time developing his own abbreviation code system. It could be Materials, though.
 
  #14  
Old 04-19-15, 06:23 PM
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bdge WINS ! he must've started out in dot mtls well done !!!

this is an interesting challenge - probably out of the diy realm of possibility in view of the posts,,, on 1 hand is a inexperienced unknowing h/o who has already spent $ for inadequate mtls vs a qualified experienced contractor - a dilemma !

everytime i see popouts the underlying strata reveals the color of the conc,,, i'm sure its possible BUT i've never seen stamped colored concrete,,, usually the conc's placed then the color coat is broadcast & troweled into surface,,, release is then broadcast & stamping then takes place,,, usually the next day excess release is pressure washed off, the slab's allowed to dry, & sealing takes place,,, fairly simple process for experienced artisans.

maybe its time to invest the $ & have it done right if possible - there's always a 1st time for everything !
 
  #15  
Old 04-19-15, 06:48 PM
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A quick question for the OP: did you have a specific reason for ignoring the Anvil sealer manufacturer's instructions, which state NOT (caps are theirs, not mine) for use on stamped concrete? I think doing so is asking for performance problems, but that's just me. I know I wouldn't have used that sealer on a stamped concrete patio, as manufacturers usually have valid reasons for restricting the use of their products. They usually prefer to lose a sale vs. having an unhappy customer.
 
  #16  
Old 04-20-15, 04:50 AM
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I spoke with Anvil's lead technician on which exact product I should use for my situation (3 year old patio that just needed re-sealed; wasn't sure if the original was water or acrylic based), and they actually told me to use that particular sealer and to ignore the warning. I can't recall the exact reason why, but I believe it had something to do with them not wanting anyone to seal with it where release powder would still be present. I clarified my situation a second time just to make sure that we were both on the same page with that product.
 
  #17  
Old 05-03-15, 10:02 AM
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Just to update this thread, with how much I've got going on right now, and a pulled back on top of it all, I wound up hiring a concrete resurfacing company to do the job for me (different guy than previously mentioned). The guy has been in business for 30 years, and the work of his I saw looked terrific. He used CSS Emulsion cut with xylene, and the initial results look great. Now I'll just wait and see how this holds up, though he assured me that CSS makes top quality stuff.



I do appreciate the assistance, and will likely take over sealing duties in the future now that I have a better understanding of it.
 
  #18  
Old 05-05-15, 02:30 AM
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TERRIFIC !!!!!!!!!! there's a reason good mtls work well in the hands of someone who's experienced & skilled,,, css is made by elitecrete & all their artisans are trained & licensed in & for its use,,, if you don't mind, pls pm me w/his name,,, thanks in adv
 
  #19  
Old 05-05-15, 04:03 AM
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Was that concrete material originally purchased and installed in big sheets (like 4' X 8") ?

I'm surprised at how many long lines exist and by the number of extremely narrow pieces that are present along those long lines . . . . so that it looks like they were arranged at a factory instead of being randomly positioned on-site.

But I also know that any sheets would be way too heavy to be maneuvered at a work site.
 
  #20  
Old 05-06-15, 05:05 AM
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stadry: Sent.

Vermont: The patio (approximately 425 square feet) was poured on-site, and those lines you're seeing are the control joints. There are a number of them, but they all line up with the joints from the stamp pattern, so you it really blends in well in person. The photo above has the contrast much higher than normal to show that the initial problem was resolved.
 
  #21  
Old 05-20-15, 02:54 AM
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Hi there. Thought i'd add my knowledge into this....been reading about stamped concrete and my concrete also had white spots after winter. Long story short...it was due moisture being trapped under the surface and pulling away the sealer from the surface (in other cases it could be efflorescence). The worst mistake one can do is reapply a sealer to your concrete....the solution is to apply xylene (assuming you existing sealer is solvent based). What it does is put back your original sealer into its liquid state and the white spots can finally disappear...once it all dries your concrete will look like its brand new again. Most people from what i read will just think to reapply another sealer coat which will make the whitening get worse. When it happens again just keep using xylene....that is, until your existing sealer finally exhausts itself in a few years.
 
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