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Re: Best grog for refractory?

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  • alaska_woodwright_and_blacksmith
    Dave: Essentially, you have it right. My inner most layer is a 1/4 to 1/2 inch of commercial refractory cement rated to 4000 degrees. Behind this is a 4 1/2
    Message 1 of 17 , Aug 31, 2006
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      Dave:
      Essentially, you have it right. My inner most layer is a 1/4 to 1/2
      inch of commercial refractory cement rated to 4000 degrees. Behind
      this is a 4 1/2 inch layer of homemade refractory. Behind this is 2"
      of Kaowool which backs up against the chachambers outsside steel walls.

      Research until you find what may work for you.

      Jon-Taylor
    • Dave Mucha
      ... I am curious about furnaces in general. still getting parts together to make my first one, it seems that some people just a steel can and not insulation at
      Message 2 of 17 , Sep 1, 2006
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        --- In hobbicast@yahoogroups.com, "alaska_woodwright_and_blacksmith"
        <alaska_woodwright_and_blacksmith@...> wrote:
        >
        > Dave:
        > Essentially, you have it right. My inner most layer is a 1/4 to 1/2
        > inch of commercial refractory cement rated to 4000 degrees. Behind
        > this is a 4 1/2 inch layer of homemade refractory. Behind this is 2"
        > of Kaowool which backs up against the chachambers outsside steel walls.
        >
        > Research until you find what may work for you.
        >
        > Jon-Taylor
        >

        I am curious about furnaces in general. still getting parts together
        to make my first one, it seems that some people just a steel can and
        not insulation at all. melt in 10 minutes and keep everything at a
        safe distance.

        others use one layer of homemade and some times a metal liner,
        (leaving the metal casting can in place) sometimes nothing but their
        homemade refractroy.

        As for Grahams project, he said electric, so that means good insulation.


        But for gas or oil, I would think it would take well more than 10
        minutes to heat an outter can to warm when there is a 2 inch layer of
        homemade refractory in place ?

        Dave

        Funny how so many questions go away once one actually starts melting
        things.
      • Jack
        Not wrong enough to be a problem! Adding insulating blankets outside the refractory is meant to keep heat IN, maybe help keep the outer walls/workshop cooler.
        Message 3 of 17 , Sep 1, 2006
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          Not wrong enough to be a problem!

          Adding insulating blankets outside the refractory is meant to keep heat
          IN, maybe help keep the outer walls/workshop cooler.

          My furnace has ONLY 2 inch thick 3000 degree refractory lining - no
          ceramic wool etc. Starting from cold, it takes about 30 minutes before
          the outer shell is too hot to touch with the fingers. Since I run it
          out of doors, heat in the workshop is not a consideration.

          Home made refractory is definitely the hard way to go since ready-made
          is so easily obtained from foundry supply companies. In addition, the
          commercial product will meet temperature specifications or the company
          will hear about it in no uncertain terms!
          Jack





          --- In hobbicast@yahoogroups.com, "Dave Mucha" <dave_mucha@...> wrote:
          >
          > I thought that refractory was to be harder and rated for higher temps
          > and was the inner liner, if there are more than one liner, refractory
          > is the one in direct contact with the heat source. That refractory
          > got some abuse other than thermal and should be hard(er).
          >
          > and that the insulation liner was the outer liner and it's purpose was
          > to prevent heat transfer. it has no real requirement for strength
          > other than being strong enough to hold things in place.
          >
          > And that separate layers are not required, but that any layer that is
          > in contact with direct heat should be rated for more heat.
          >
        • Daniel C Postellon
          The refractory is not a great conductor, and you are haeting it from the inside. The inside of the furnace is much hotter than the outside. I made my own
          Message 4 of 17 , Sep 2, 2006
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            The refractory is not a great conductor, and you are haeting it from the
            inside. The inside of the furnace is much hotter than the outside. I made
            my own refractory with half clay and half vermiculite (by volume), and the
            outside is warm when the inside is hoy enough to melt aluminum.

            > But for gas or oil, I would think it would take well more than 10
            > minutes to heat an outter can to warm when there is a 2 inch layer of
            > homemade refractory in place ?
          • grantfair2001
            Thanks for all the replies. I gather everyone thinks the best grog is no grog? I have already bought the K23 insulating brick, and put element-holding
            Message 5 of 17 , Sep 2, 2006
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              Thanks for all the replies. I gather everyone thinks the best grog is
              no grog? <g>

              I have already bought the K23 insulating brick, and put
              element-holding grooves in it. There can be trouble getting reliable
              grooves of the right size and depth to retain the element in solid
              refractory. After the refractory is cast it is very difficult to
              change the groove size. With K23 getting the right size of groove
              consistently was easy. I used a cheap tile saw and a shop-made jig to
              hold the bricks while cutting. To get the elements into the grooves
              will require a bit of force (I have already tried it with success) but
              the result is that the elements are far less likely to pop out.

              I have some ITC-100 which I will paint on the inner surfaces of the
              K23 brick. This both provides extra strength to the bricks, and
              results in much improved heat retention. I think it is made of
              zirconia, which is even more refractory than alumina. The K23 bricks
              are crumbly, but I also plan to make a frame and pivoted lifting
              handle which will lift the furnace straight up off the crucible. If
              this succeeeds I hope it, along with the strength added by the
              ITC-100, minimizes damage to the bricks,

              The suggestions that I just buy some refractory are tempting. Howver
              there is no local (Toronto) over-the-counter source of refractory, so
              we are talking about substantial transportation costs, so the
              refractory could cost up to $200 Can. Importing refractory from the
              states is even more costly. UPS charges for clearing customs can
              double the price of an item. I was just looking at some Sparlite25
              refractory on Ebay; the starting bid price was $29.00. The UPS
              standard cost to Canada for 70 pounds was about $50. That's before the
              customs clearing costs, as well as the taxes collected at the border.
              And 70 pounds only fills one cubic foot. I need two.

              I already have have 50 pounds of Kaolin, 50 pounds of white ball clay,
              and 50 pounds of Kyanite, plus a big pail of sawdust from Home Depot
              and a bag of much courser sawdust from a lumber mill up north. Total
              cost about $50.

              If you search on "sawdust" in this conference you will find that
              Carlos made refractory from a similar recipe (except his grog was
              crushed insulating firebrick) and he found it left his furnace surface
              relatively low temperarature. The only drawback was shrinkage.

              I'm not suggesting the advice offered is wrong for others, just not
              where I am headed for the reasons outlined. If I screw up I will be
              the first to say you told me so <g>.

              Grant
            • alaska_woodwright_and_blacksmith
              Dave: My foundry, though large, is ready to melt AL in about 18 minutes. I know mine is a bit overkill, but I routinely melt steel to caste specialty
              Message 6 of 17 , Sep 2, 2006
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                Dave: My foundry, though large, is ready to melt AL in about 18
                minutes. I know mine is a bit overkill, but I routinely melt steel to
                caste specialty woodwright tools. My furnace can run to just around
                3900d and with the thickness of refractory and added kaowool, the
                outside is hot, but nor dangerously or injuriously so.

                JTL
              • alaska_woodwright_and_blacksmith
                Dave: It occurs to me that I did not ask where you are? While Jack raises a good point, the nearest supplier of such refractory material to Fairbanks, AK, is
                Message 7 of 17 , Sep 2, 2006
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                  Dave: It occurs to me that I did not ask where you are? While Jack
                  raises a good point, the nearest supplier of such refractory material
                  to Fairbanks, AK, is at such a distance that shipping costs far
                  outweigh the price of the refractory. Commercial or homemade, you have
                  to plan for your circumstance.

                  JTL
                • Rick Rowlands
                  What kind of furnace are you using? Rick ... From: alaska_woodwright_and_blacksmith To: hobbicast@yahoogroups.com Sent: Sunday, September 03, 2006 2:08 AM
                  Message 8 of 17 , Sep 3, 2006
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                    What kind of furnace are you using?

                    Rick
                    ----- Original Message -----
                    From: alaska_woodwright_and_blacksmith
                    To: hobbicast@yahoogroups.com
                    Sent: Sunday, September 03, 2006 2:08 AM
                    Subject: [hobbicast] Re: Best grog for refractory?


                    Dave: My foundry, though large, is ready to melt AL in about 18
                    minutes. I know mine is a bit overkill, but I routinely melt steel to
                    caste specialty woodwright tools. My furnace can run to just around
                    3900d and with the thickness of refractory and added kaowool, the
                    outside is hot, but nor dangerously or injuriously so.

                    JTL





                    [Non-text portions of this message have been removed]
                  • Andrew Werby
                    1a. Re: Best grog for refractory? Posted by: grantfair2001 grant.fair@sympatico.ca grantfair2001 Date: Sat Sep 2, 2006 5:11 pm (PDT) Thanks for all the
                    Message 9 of 17 , Sep 3, 2006
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                      1a. Re: Best grog for refractory?
                      Posted by: "grantfair2001" grant.fair@... grantfair2001
                      Date: Sat Sep 2, 2006 5:11 pm (PDT)

                      Thanks for all the replies. I gather everyone thinks the best grog is
                      no grog? <g>

                      [snip]

                      The suggestions that I just buy some refractory are tempting. Howver
                      there is no local (Toronto) over-the-counter source of refractory, so
                      we are talking about substantial transportation costs, so the
                      refractory could cost up to $200 Can. Importing refractory from the
                      states is even more costly. UPS charges for clearing customs can
                      double the price of an item. I was just looking at some Sparlite25
                      refractory on Ebay; the starting bid price was $29.00. The UPS
                      standard cost to Canada for 70 pounds was about $50. That's before the
                      customs clearing costs, as well as the taxes collected at the border.
                      And 70 pounds only fills one cubic foot. I need two.

                      [Searching for "castable refractory" and "Ontario" I came up with this
                      company:

                      Glasrock Products 268-274 South Service Rd
                      Stoney Creek, ON , L8E 2N9
                      Phone: 905-664-5300
                      FAX: 905-664-5438
                      E-Mail: glasrock@...





                      I already have have 50 pounds of Kaolin, 50 pounds of white ball clay,
                      and 50 pounds of Kyanite, plus a big pail of sawdust from Home Depot
                      and a bag of much courser sawdust from a lumber mill up north. Total
                      cost about $50.

                      [Figure your cost to mix up and install this stuff, then add the cost of
                      chipping it out and throwing it away...]

                      If you search on "sawdust" in this conference you will find that
                      Carlos made refractory from a similar recipe (except his grog was
                      crushed insulating firebrick) and he found it left his furnace surface
                      relatively low temperarature. The only drawback was shrinkage.

                      [The crushed soft firebrick would make this mix lighter and less liable to
                      shrink. Regular grog would not work as well.]

                      I'm not suggesting the advice offered is wrong for others, just not
                      where I am headed for the reasons outlined. If I screw up I will be
                      the first to say you told me so <g>.

                      Grant

                      [Do let us know...]

                      Andrew Werby
                      www.unitedartworks.com
                    • Rupert Wenig
                      Hello Andrew, You can get all the refractory you want from Dukast in Montreal. No need to pay UPS their high fee for bringing anything across the line. They
                      Message 10 of 17 , Sep 3, 2006
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                        Hello Andrew,
                        You can get all the refractory you want from Dukast in Montreal. No
                        need to pay UPS their high fee for bringing anything across the line.
                        They may have a dealer near you as well.

                        Rupert

                        Andrew Werby wrote:
                        > 1a. Re: Best grog for refractory?
                        > Posted by: "grantfair2001" grant.fair@... grantfair2001
                        > Date: Sat Sep 2, 2006 5:11 pm (PDT)
                        >
                        > Thanks for all the replies. I gather everyone thinks the best grog is
                        > no grog? <g>
                        >
                        > [snip]
                        >
                        > The suggestions that I just buy some refractory are tempting. Howver
                        > there is no local (Toronto) over-the-counter source of refractory, so
                        > we are talking about substantial transportation costs, so the
                        > refractory could cost up to $200 Can. Importing refractory from the
                        > states is even more costly. UPS charges for clearing customs can
                        > double the price of an item. I was just looking at some Sparlite25
                        > refractory on Ebay; the starting bid price was $29.00. The UPS
                        > standard cost to Canada for 70 pounds was about $50. That's before the
                        > customs clearing costs, as well as the taxes collected at the border.
                        > And 70 pounds only fills one cubic foot. I need two.
                        >
                        > [Searching for "castable refractory" and "Ontario" I came up with this
                        > company:
                        >
                        > Glasrock Products 268-274 South Service Rd
                        > Stoney Creek, ON , L8E 2N9
                        > Phone: 905-664-5300
                        > FAX: 905-664-5438
                        > E-Mail: glasrock@...
                        >
                        >
                        >
                        >
                        >
                        > I already have have 50 pounds of Kaolin, 50 pounds of white ball clay,
                        > and 50 pounds of Kyanite, plus a big pail of sawdust from Home Depot
                        > and a bag of much courser sawdust from a lumber mill up north. Total
                        > cost about $50.
                        >
                        > [Figure your cost to mix up and install this stuff, then add the cost of
                        > chipping it out and throwing it away...]
                        >
                        > If you search on "sawdust" in this conference you will find that
                        > Carlos made refractory from a similar recipe (except his grog was
                        > crushed insulating firebrick) and he found it left his furnace surface
                        > relatively low temperarature. The only drawback was shrinkage.
                        >
                        > [The crushed soft firebrick would make this mix lighter and less liable to
                        > shrink. Regular grog would not work as well.]
                        >
                        > I'm not suggesting the advice offered is wrong for others, just not
                        > where I am headed for the reasons outlined. If I screw up I will be
                        > the first to say you told me so <g>.
                        >
                        > Grant
                        >
                        > [Do let us know...]
                        >
                        > Andrew Werby
                        > www.unitedartworks.com
                        >
                        >
                        >
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                        --
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                        Rupert Wenig
                        Camrose, Alberta, Canada.

                        http://www3.telus.net/public/rwenig/
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