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Sodium Silicate Concrete Sealer - Forno Bravo Forum: The Wood-Fired Oven Community



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Sodium Silicate Concrete Sealer

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  • Sodium Silicate Concrete Sealer

    I've poured a slab and troweled it too late (it was 40 degrees and didn't set for about 24 hours) and have quite a bit of dusting. I've gotten hold of several gallons of sodium silicate (water glass) and was wondering if I should apply the stuff to the concrete when it is wet or dry? Seems to me like it should be dry so as to get the best penetration of the chemicals into the concrete?? Then again, maybe wet is better??

    Does anybody know anything about this stuff?

  • #2
    Re: Sodium Silicate Concrete Sealer

    We've heard about waterglass in connection to high heat mortar ingredients, and as a binder for vermiculite. You're coating concrete? Tell all.
    My geodesic oven project: part 1, part 2


    • #3
      Re: Sodium Silicate Concrete Sealer

      I built an Alan Scott brickoven two years ago. Wanting a nice smooth hearth, stupid me took a belt sander to the fire bricks. Dumb beyond belief, of course.
      Potter friends turned me on to sodium silicate, or 'liquid glass'. I determined it was absolutely food safe. Also very cheap - $7.00/gal. Put several coats on dry firebricks.
      I applied several coats -- smooth as glass!!!
      Am extremely happy with our sodium silicate-enchanced oven.



      • #4
        Re: Sodium Silicate Concrete Sealer

        What I've read is that the chemicals actually bind to the inorganic components of the concrete, filling any tiny voids left by evaporating water as the concrete cures, and somehow (almost magically) converts the surface into something akin to glass, even without the application of heat. The process actually penetrates the surface for some distance making the surface absolutely water and oil/antifreeze/and other-garage-stuff proof. Then the surface may be painted with whatever you like and avoid the problems of surface moisture coming through the slab (no, I didn't include a vapor barrier below the slab).

        Anyhow, this seems like the cat's meow for concrete sealers, but it's not readily available in this country for that purpose. You can get it in Europe and Australia marketed for this not in the U.S. kinda strange.


        • #5
          Re: Sodium Silicate Concrete Sealer

          hornofan, what issues have you determined were caused by the belt sander method? Quite a few of this forum's members have used it without any ill effects, including myself. I am coming up on 3 yrs since my first fire, have had zero issues with my hearth bricks (or any part of the dome for that matter).
          Just curious.



          • #6
            Re: Sodium Silicate Concrete Sealer

            That was to be my next question too ...

            Check these links re: sealing concrete with sodium silicate
            http://www.wetsealers.com/CONSEAL1000.html (Wsconsin)
            http://www.sealacrete.com.au/index.html (Australia)

            What I've got is the 40% solution (the same stuff recently used for the Clunkers program to disable auto engines). It looks like I can dilute that with water 4:1 and generously mop it on to concrete, let it sit for a couple of days (mopping up any puddles in the process), and repeat a couple of times.
            Last edited by lwalper; 01-17-2010, 11:06 PM.


            • #7
              Re: Sodium Silicate Concrete Sealer

              hello all, i have aquired some sodium silicate wanting to apply it to the refractory base inside my oven, but found it crumbles when it goes near fire. has anyone else used it in the oven where it will get hot and touch the fire? any ideas?



              • #8
                Re: Sodium Silicate Concrete Sealer

                I don't quite know what you want to do or why. Sodium silicate is usually an ingredient in refractory mortar, I don't know what it would do by it's self.
                My geodesic oven project: part 1, part 2


                • #9
                  Re: Sodium Silicate Concrete Sealer

                  It shouldn't "crumble" with the heat, but from what I understand I'm not sure there's going to be any advantage to applying it in this setting. I know the previous poster reports good results, and I don't doubt that a bit, but in my oven floor I used a diamond plane (a rotary blade sort of thing mounted on my 4" angle grinder - intended to be used in the flat position as opposed to vertically like a saw blade). After laying the brick in fireclay and getting them as close to level and smooth as possible, there were still small (perhaps insignificant) discrepancies between brick due to the warping of the brick caused by the brick firing. I just went over the entire hearth with the plane. Overall I might have removed one millemeter of material - not much, but enough to keep the peel from catching on any little bumps.

                  Any cracks or minor defects in the brick face will be filled with ash. Yep, there will be a little on your bread, but if you sweep and mop the hearth before baking that should not really be a problem.


                  • #10
                    Re: Sodium Silicate Concrete Sealer

                    wow i hadnt thought of mixing th silicate with the concrete, now my experiments for making floor tiles that arnt too dusty are going much better.

                    This can also be achieved by casting up the concrete on plastic and using the plastic covered side as the top, a little wear though and it probably wont last too long!