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Type of sand for sand form in cob oven - Forno Bravo Forum: The Wood-Fired Oven Community



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Type of sand for sand form in cob oven

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  • Type of sand for sand form in cob oven

    Hi everyone, I'm almost at the point of ordering sand and clay for building the dome. From what I've read, angular sand is recommended for for the actual dome, but I can't find anything on what to use for the form.

    Is angular sand also best for making a sand form that'll stay together, or do I need a smoother, more fine sand? My oven will have a 30" inner diameter.

  • #2
    Re: Type of sand for sand form in cob oven

    Sharp grained aggregate is best for all masonry work.
    Old World Stone & Garden

    Current WFO build - Dry Stone Base & Gothic Vault

    When we build, let us think that we build for ever.
    John Ruskin


    • #3
      Re: Type of sand for sand form in cob oven

      Put a small amount of clay in the sand and slightly damp so that it holds its shape for the mold. Include some plastic drink bottles in your mold you'll have less sand to shovel out at the end.
      Regards dave
      Last edited by cobblerdave; 08-02-2013, 01:11 PM. Reason: Spelling
      Measure twice
      Cut once
      Fit in position with largest hammer

      My Build
      My Door


      • #4
        Re: Type of sand for sand form in cob oven

        If you want to get really accurate the ratio is around 10% water. Polystyrene fruit boxes are also good to stack under the sand castle to reduce the amount of sand required. Use a stick, cut to length, of the internal dome height, placed vertically in the centre of your floor.It is pretty easy to get a perfect hemisphere by eye, working from the centre point at the top and down to your perimeter at the base. Use the flat of a trowel to tap the sand into the required form on the outside.
        Kindled with zeal and fired with passion.