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I just finished sealing my asphalt driveway yesterday morning. Temps have been in the mid 90's and humid, and there's been no rain. As of this question, it's been about 36 hours since I sealed the driveway. I'm starting to see multiple stains like the picture below coming through the sealant. I think they were there before, but I thought they were just where the asphalt had worn more excessively. I'm not really concerned about looks. What is this and should I be concerned about it?

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TheOtherTimDuncan
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  • please post pics of few others. placing a coin in the photo will give a sense of scale. how did you prep the drive? what is the name of the product that you used? – mike Jul 18 '13 at 23:25
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    I've added new pictures with a quarter for scale. I used Latex-ite airport grade from Home Depot. The only prep I did was to clean the driveway using the same brand cleaner. I did the cleaning around 6 PM the night before. I primarily hosed off the driveway but spot scrubbed with a stiff brush maybe half of it. – TheOtherTimDuncan Jul 19 '13 at 22:35
  • Are you sure it's a stain on top of the seal, and not dirt or other debris that was under the seal wearing through? The splatter patterns on the top photo would seem to be key. I'd start investigating whether those came from above or below the seal. My suspicion is that the driveway wasn't clean enough, but I don't have enough experience to suggest a fix. – BMitch Jul 19 '13 at 22:37
  • I have read that when one applies certain seal coatings and then there's an unexpected rain, something milky appears. So maybe this is some component of th product you used. – aparente001 Mar 11 '19 at 07:49

2 Answers2

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BMitch is right on his comment. This probably wasn't "dirt" but was some oil, rust, other chemicals... When you paint over them you dry them out and the result is a chemical reaction with the paint/stain because you are drying the material out - it cannot access air - and it will try to escape through the stains you see.

I know this because I paint my laundry floor every 3-4 years and I sweep it well but really don't feel like giving it a good cleaning. My fix is to just put more paint over it - which works sometimes on the first coat and sometimes 2-3 coats later. Is the paint bonded as good as it could be? No. But it is a floor. If you don't want to see these you have to do some serious cleaning before painting floors/driveways.

DMoore
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  • Seems reasonable. I agree with BMitch that it appears to be coming through from below. As long as it's cosmetic, and I don't have to worry about the seal coat flaking off in a couple days, it's not a big deal. Next time I do the driveway I'll clean it more thoroughly and maybe put some sealant over these spots. – TheOtherTimDuncan Jul 20 '13 at 22:05
  • It will flake in those areas easier for sure. I have personally witnessed it. You will have to add more coats or sand and repaint. – DMoore Jul 21 '13 at 04:24
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I have a 300 ft driveway, and I only have white spots like yours on the asphalt walkway from front door to driveway, about a 20 ft section. This is the only area i use rock salt on during the winter. The rest of the driveway is OK.

I found the easiest way to remove it is with a propane torch (plumbing type). Be careful not to overheat the spot as you will loosen up the asphalt. The amount of heat to apply depends on how thick the spot is; a thicker spot will turn yellow and can be brushed away, while thin spots will disappear.

It's a good idea to seal coat afterwards.

Niall C.
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jack
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