web analytics
Troweling refractory domes on sand forms - Forno Bravo Forum: The Wood-Fired Oven Community

Announcement

Collapse

I'm Peter Reinhart! Ask Me Anything! Monday, February 15, 2016 7:00-8:00 pm EST

To kick off our AMA feature, we have invited author, chef and master bread maker and host of Pizza Quest, Peter Reinhart, to be our first host! Peter will be in the Forum on Monday, February 15th, from 7:00 - 8:00 pm EST. If you are unable to be online during the live session, you can post your questions in the sticky post. Peter will answer those questions during the live session on February 15th. You can view Peter's answers to your questions as well as what happened during the live session in the session thread.

Ask Me Anything New Forum Feature

You will notice a new forum at the top of the main page called, "Ask Me Anything". This forum will be used for live one hour "Ask Me Anything" (AMA) sessions hosted by people who are knowledgeable in different areas pertaining to wood fired ovens. How it works:
- Each AMA will have a "sticky" thread where the community can post questions they would like answered during the live session. This will allow everyone to participate even if you can't be online for the live session. These questions will not be answered by the host until the live AMA; if you need an answer quickly, you should post it in the appropriate Forum area for the community to respond.
- Another thread will be posted for the live AMA. Registered users who are logged in during the live session can interact with the host by asking questions and receiving responses.
- The live thread will remain in the AMA forum to view after the session.

We hope you enjoy this new feature! Please let us know if there is a topic that you'd like to have as an AMA and we'll look for a host!

Forno Bravo
See more
See less

Troweling refractory domes on sand forms

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Troweling refractory domes on sand forms

    Has any one had experience of making a dome on a wet sand form, troweling refractory cement to thickness to make a casa style oven?

    1. Have you had luck troweling onto the vertical surfaces without an external form? (use low slump mix?)

    2. Any thoughts about using ceramic fiber in the refractory mix to reduce cracking?

    3. Also, I'm concerned about cracks/leaks in a indoor installation. any thoughts on how to make the lining as durable as possible?

  • #2
    Re: Troweling refractory domes on sand forms

    Hi Taharvey
    Check out the thread on "Castable Refractory Concrete".
    I used fatty sand (Brick sand) as a mould then covered it with builders plastic sheet before covering with castable refractory concrete. This stops the sand from absorbing water from the mix and reducing its strength. If you mix it right there is only a little slumping going to happen for the first 6" up the dome or so. I ended up with a cast dome of at least 4" with around 6" at the base line. Don't add to much water to the mix as this weakens the mix and you'll have the mix slumping. I sort of held in in place with a wide plastering type trowel for a little while so that it cured slightly and stayed in place. Mix in small batches (one 20Kg bag at a time. It took under 2 hours to complete. No need for an external form, it gets easier as you work up the dome. Trowel the mix on in stages around the base and keep pushing it up into the right place until it starts to hold its form. Not sure about added ceramic fibre.
    After gentle curing over about 2 weeks it works fine - no cracks at all and cooks a mean pizza.
    Happy to post pics or supply more info if you need.
    Cheers Willy
    Last edited by wild_willy; 02-22-2009, 08:06 AM. Reason: addedd info

    Comment


    • #3
      Re: Troweling refractory domes on sand forms

      Pics would be great!!

      Comment


      • #4
        Re: Troweling refractory domes on sand forms

        Castable manufacturers sometimes add natural fibres which help eliminate slump cracks but they're really there to burn out at low temps which leaves minute pipes which steam can escape from. Reinforcing is usually added in the form of stainless steel "needles" which are not actually needles but flat, curly, non pointy things.A one piece dome is subject to extreme stress due to the uneven heating. The top of the dome gets really hot first while the base is quite cool. This creates uneven expansion. The dome is best made in sections to accomodate the heat expansion.
        Kindled with zeal and fired with passion.

        Comment


        • #5
          Re: Troweling refractory domes on sand forms

          Originally posted by taharvey View Post
          Has any one had experience of making a dome on a wet sand form, troweling refractory cement to thickness to make a casa style oven?

          1. Have you had luck troweling onto the vertical surfaces without an external form? (use low slump mix?)

          2. Any thoughts about using ceramic fiber in the refractory mix to reduce cracking?

          3. Also, I'm concerned about cracks/leaks in a indoor installation. any thoughts on how to make the lining as durable as possible?
          I have done exactly what you are asking without a problem. I formed my dome using "brickie's" sand and styrene cut to form the curve. I then covered it in a thin plastic sheet(see pic), and then trowelled on my refractory cement with stainless steel needles. When dry, I dug everything out through the doorway and peeled off the plastic sheet from the inside, which left a nice smooth surface.
          The pics show the refractory layer ONLY (before I insulated it).
          Last edited by Balthazar; 03-20-2009, 12:57 AM.

          Comment

          Working...
          X