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Concrete Sealer

MALCOLM TAYLOR | Posted in General Questions on

This is a bit beyond the remit of GBA but I’d be grateful of any advice.

My main floor is a sealed concrete slab. it is now 25 years old and needs renewing. The original sealer was Xylene-based, and I’d prefer to switch to a water-based one. 

The advice seems to be the only way to do that is to remove the first sealer. I think it would sand off fairly easily, but some will have penetrated the surface of the concrete. I wonder if the water-based sealer will adhere if there is some residual in the slab?

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  1. user-2310254 | | #1

    Hi Malcolm,

    Maybe this post will be helpful:

    1. Expert Member
      MALCOLM TAYLOR | | #2

      Thanks Steve,

      I'm beginning to think I may have to re-seal with something solvent-based. I can't see acid etching or grinding being feasible while we live here.

      Then again Xylene sealers are awful. One whiff and you have a headache for hours.

      1. Expert Member

        I was going to post that, but without having any real backup source I refrained. The solvent is gone by now, but you still have whatever it was carrying absorbed in the concrete. You might take a chance on a trial location in a pantry or somewhere to see how much you have to sand off before the concrete absorbs water. until then I don't think it would be helpful to try and seal over top with a water based sealer.

        I've called foundation armor before and asked questions, they were generally pretty helpful. maybe give them a ring and see if they have a product that can be applied over, or something to remove what was there?

  2. aaronbeckworth | | #4


    On the topic of concrete sealing options, I wonder if you’ve ever heard of concrete being chemically sealed as opposed to having a sealer applied? In Taunton’s 2019 Small Houses book, there is a house in TX featured with this written about some of the details,

    “…concrete floors throughout the house are virtually indestructible and we’re chemically sealed as opposed to having a sealer applied. The more they’re used, the more polished they will appear.”

    1. Expert Member
      MALCOLM TAYLOR | | #5


      No I haven't seen that. Sounds interesting although I suspect that isn't an option for me as the concrete is down and sealer applied.

      As the issue in my place in entirely cosmetic, I may try and apply a concrete wax top-coat, which would be the easiest solution by far.

  3. linnoiemclaren | | #6

    Hi there, and thanks for starting this thread. I am gonna bump it a little, and that's because, unfortunately, I did not find another on this topic. So, apparently, the folks that poured the concrete floors in my shop did not abide by the rules you mentioned. There are multiple cracks all around. These cracks are not critical, but I still have the feeling they are spreading. So I was wondering if you guys know about this sealer and whether it's worth buying.

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