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  • Refractory Mix Cracking

    Hi Can Anyone Tell Me Why ? The Refactory Sila Mix Im Using In Perth W.A
    Is Cracking, Im Weting The Bricks And The Mix Im Making maybe A Little to moist

    Cheers Pat

  • #2
    Re: Refractory Mix Cracking

    Did you use the premixed refractory mortar? Im building a small scale prototype(cant afford the real one yet, but want to practice with the materials), and here in Salt Lake the premixed product is much easier to get ahold of. It comes mixed VERY wet, and from my experience, wet cements are more likely to crack. More water in the mix means more volume, and when the mix dries(even though it is a chemical reaction, not just drying), water is forced out of the cement, and this means a loss of volume. this causes shrinking.
    I think. Anyone more experienced here wana back me up?

    Comment


    • #3
      Re: Refractory Mix Cracking

      Cheers for your input!
      I,m not using a premix with water, rather a dry - premix. But what I've since learned in the forums , The're suggesting not to use an air-dry, mortar, for exactly the reasons I'm encountering !

      Cheers
      Pat

      Comment


      • #4
        Re: Refractory Mix Cracking

        All refractory mortars I know of will shrink somewhat. If you are spanning a joint of more than 1/4 inch or so expect cracks. If you want to span a larger joint - extend the mortar with a sharp sand (mortar sand or silica sand). For 1/2 inch span, go with a 1 to 1 ratio, 1 inch span try a 3 sand to 1 mortar mix ratio. If you have tapered joints, try having two mortars - "neat" for the tight part and "extended" for the wider part.

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        • #5
          Re: Refractory Mix Cracking

          Cheers for the info Neil, ended up going with the fireclay , lime,sand and cement mix recomended by Forno Bravo, and now have completed the oven. Now been sitting for two weeks and about to start firing. Will post photo's from start to finish in the next week.

          Cheers
          Pat

          Comment


          • #6
            Re: Refractory Mix Cracking

            Hi Mark here from NSW Australia. I hope this is a suitable place to ask this question but...
            I've gotten hold of some high temperature raku clay and intend to mix it with lime and sand for a dome mortar - what do you guys reckon??
            ta

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            • #7
              Re: Refractory Mix Cracking

              Originally posted by Westozchoppers View Post
              Cheers for the info Neil, ended up going with the fireclay , lime,sand and cement mix recomended by Forno Bravo, and now have completed the oven. Now been sitting for two weeks and about to start firing. Will post photo's from start to finish in the next week.
              Hi Pat;

              Where did you find fire clay in Perth? And did it hold up OK once fired?
              I'm in the process of finding materials at the moment, so an advice for stuff in Perth greatly appreciated.

              Comment


              • #8
                Re: Refractory Mix Cracking

                Hi Adrian,
                There's a pottery shop in Occonor. I cant remember the name right now, should be in the yellow pages under pottery supplies. There's also a perlite manufactorer in Jandacot. Fireclay has held up well well no problems as yet!If You need further help contact me at pattydazzler@hotmail.com

                Goodluck
                Pat

                Comment


                • #9
                  Re: Refractory Mix Cracking

                  Hi all,
                  well here we have a thread with a few newbies from this wonderful land of ours. Great to see the Australian increasing the forum numbers.
                  Welcome to Westozchoppers (Pat), Nokka and Adrian.
                  The poor mans version for the mortar works fine and I haven't had any problems with mine over the 18 month build time.
                  Post some pics so we can all share your joys.

                  Cheers.

                  Neill
                  Prevention is better than cure, - do it right the first time!

                  The more I learn, the more I realise how little I know


                  Neill’s Pompeiii #1
                  http://www.fornobravo.com/forum/f8/n...-1-a-2005.html
                  Neill’s kitchen underway
                  http://www.fornobravo.com/forum/f35/...rway-4591.html

                  Comment


                  • #10
                    Re: Refractory Mix Cracking

                    Thanks Pat for the pottery shop suggestions. I live North of the river, and found that Stilletano's Home Hardware in Malaga stock Fondue cement. It's $47 for a 20kg bag, but it would probably cost me that much in fuel to drive to Oconner!

                    They can also get rockwool insulation for about $50 / m2.

                    I've found the perlite place in the yellow pages and will give them a call to get a price.
                    Last edited by Adrian; 01-13-2009, 03:25 AM.

                    Comment


                    • #11
                      Re: Refractory Mix Cracking

                      my old man told me that he saw fireclay for sale in bunnings the otherday so maybe check out there or ask them and they can get it in
                      Real men cook with fire
                      My Oven and Fireplace Build

                      Comment


                      • #12
                        Re: Refractory Mix Cracking

                        Originally posted by bimbo View Post
                        my old man told me that he saw fireclay for sale in bunnings the otherday so maybe check out there or ask them and they can get it in
                        Which store? I've asked at Inglewood, Morley and Balcatta for ref. cement, fire clay and rock wool. Got blank stares or confused information at all three stores, and couldn't get any of these.

                        Comment


                        • #13
                          Re: Refractory Mix Cracking

                          Hi, I found the refactory cement I used of the shelf, would crack here in W.A.
                          I tried mixing it wet and dry and soaking the bricks, the so called air dryed mix I wouil stay away from and suggest using Forno Bravos recipe,fire clay,white sand and lime.

                          Pat

                          Comment


                          • #14
                            Re: Refractory Mix Cracking

                            Thanks for the info

                            It sounds like if white washed sand works so would plasterers sand

                            Brickies sand must have too much loam

                            Originally posted by Westozchoppers View Post
                            Hi, I found the refactory cement I used of the shelf, would crack here in W.A.
                            I tried mixing it wet and dry and soaking the bricks, the so called air dryed mix I wouil stay away from and suggest using Forno Bravos recipe,fire clay,white sand and lime.

                            Pat

                            Comment


                            • #15
                              Re: Refractory Mix Cracking

                              Ask around for fire blanket, this is often rockwool

                              Originally posted by Adrian View Post
                              Which store? I've asked at Inglewood, Morley and Balcatta for ref. cement, fire clay and rock wool. Got blank stares or confused information at all three stores, and couldn't get any of these.

                              Comment

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