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Rain 4 hours after seal coat

Discussion in 'Homeowner Assistance Forum' started by antcap51, May 24, 2009.

  1. antcap51

    antcap51 LawnSite Member
    Messages: 17

    It rained a little bit after my driveway was seal coated. It was done and then rained a little 4 hours later. Might rain this afternoon as well. Will the rain affect the seal coating? It was almost dry to the touch before it rained.
  2. SurfaceMax

    SurfaceMax LawnSite Member
    from TX
    Messages: 72

    If it HAD been dry to the touch AND the rain had not been a "hard-driving" rain then it would have been OK... but if the sealer was still soft (the "almost" dry to the touch is what worries me) it will re-emulsify (absorb the water) and it will affect the quality of the performance of the sealer.
    Did it have a chance to get some sun & dry good before the next rain?
    Did you see ANY signs of the sealer "running"?
    How long was it in total before it got a chance to fully dry?

    All emulsion sealers (sealer containing water as the "carrier" rather than naphtha or other solvents) require surface tension to cure properly and achieve durability. Think of the coating as being like plastic wrap that gets "stretched" by the forces caused by the water evaporating and the sealer actually "shrinking". Loose plastic wrap won't stick and won't hold anything. But stretched tight it will seal to what it's placed on. This is a bad example because it's apples & oranges but there is actually a tremendous amount of force generated in that wet sealer film as the water leaves & the coating "shrinks" to it's final state & "sticks" to the pavement. That's why sealing is best done in sunny weather with moderate to low humidity or a combination (higher humidity but full-hot sun, lower humidity but a semi-cloudy day)
    If there is rain in the forecast and there isn't enough time for the sealer to fully dry to the touch (where you can push your thumbnail into it and not leave a very noticeable mark if any) it's not a good day for sealing.
    Sounds like your contractor was "pushing it" and your driveway may do OK but you won't ever know how well it would have done under the right conditions.
  3. antcap51

    antcap51 LawnSite Member
    Messages: 17

    Thanks for the repsonse. It had a good 4 hours of full sun low humidity to dry. No sealer was running off. I didnt touch it so not sure if it was dry to the touch.

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