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Need advice

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  • crashbone256
    Group: I made the mold from eps. I taped the edges with masking tape. I encased the mold in POP. The mold was oven dried at 170 F for 12 hours. Then 8 hours at
    Message 1 of 24 , Apr 9, 2013
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      Group:

      I made the mold from eps. I taped the edges with masking tape.
      I encased the mold in POP. The mold was oven dried at 170 F for 12 hours.
      Then 8 hours at 200 F. Acetone was poured into the mold the dissolve the
      styrofoam. The mold was dried at 210 F for 3 hours. The 200F molds were buried in new dry sand to near the top.

      5 # Al muffins were melted in a 10 # crucible. The crux was red hot when removed.

      As the Al melt was poured into the "empty" mold it bubbled and popped and blew
      bubbles up through the sprue. A steady stream was being poured, but it didn't want to go down the sprue.

      You can see from the first picture how it was gated.
      Sprued on the top, Al runs down into the mold and rises off the bottom.

      The casting is porous and crappy.
      What to do next time?


      Thanks
      lance
      ++++


      http://groups.yahoo.com/group/hobbicast/photos/album/1891226731/pic/list
    • Jeshua Lacock
      ... Sounds like the POP had far too much water in it still. I would dry it out more around 400F. When I do lost plastic casting (a bit different of course) I
      Message 2 of 24 , Apr 9, 2013
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        On Apr 9, 2013, at 8:06 PM, crashbone256 wrote:

        > I made the mold from eps. I taped the edges with masking tape.
        > I encased the mold in POP. The mold was oven dried at 170 F for 12 hours.
        > Then 8 hours at 200 F. Acetone was poured into the mold the dissolve the
        > styrofoam. The mold was dried at 210 F for 3 hours. The 200F molds were buried in new dry sand to near the top.
        >
        > 5 # Al muffins were melted in a 10 # crucible. The crux was red hot when removed.
        >
        > As the Al melt was poured into the "empty" mold it bubbled and popped and blew
        > bubbles up through the sprue. A steady stream was being poured, but it didn't want to go down the sprue.
        >
        > You can see from the first picture how it was gated.
        > Sprued on the top, Al runs down into the mold and rises off the bottom.
        >
        > The casting is porous and crappy.
        > What to do next time?

        Sounds like the POP had far too much water in it still.

        I would dry it out more around 400F. When I do lost plastic casting (a bit different of course) I heat the POP mold up to around 1000F...


        Best,

        Jeshua Lacock
        Founder/Engineer
        3DTOPO Incorporated
        <http://3DTOPO.com>
        Phone: 208.462.4171
      • Eggleston Lance
        OK, will dry 400-700 F. Would it work better to fill from the bottom and vent at the top ? lance ++++ ... [Non-text portions of this message have been removed]
        Message 3 of 24 , Apr 9, 2013
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          OK, will dry 400-700 F.

          Would it work better to fill from the bottom and
          vent at the top ?

          lance
          ++++
          On Apr 9, 2013, at 10:19 PM, Jeshua Lacock wrote:

          > Sounds like the POP had far too much water in it still.
          >
          > I would dry it out more around 400F. When I do lost plastic casting (a bit different of course) I heat the POP mold up to around 1000F...



          [Non-text portions of this message have been removed]
        • Jeshua Lacock
          ... I don t think so. If there is too much moisture in the mold you are going to have issues no matter what. Best, Jeshua Lacock Founder/Engineer 3DTOPO
          Message 4 of 24 , Apr 9, 2013
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            On Apr 9, 2013, at 11:07 PM, Eggleston Lance wrote:

            > OK, will dry 400-700 F.
            >
            > Would it work better to fill from the bottom and
            > vent at the top ?

            I don't think so. If there is too much moisture in the mold you are going to have issues no matter what.


            Best,

            Jeshua Lacock
            Founder/Engineer
            3DTOPO Incorporated
            <http://3DTOPO.com>
            Phone: 208.462.4171
          • tmoranwms
            PoP dries out in three stages: 1. Absorbed moisture. This is mostly driven off at any temperature with low humidity (with the dry air around here in winter,
            Message 5 of 24 , Apr 9, 2013
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              PoP dries out in three stages:
              1. Absorbed moisture. This is mostly driven off at any temperature with low humidity (with the dry air around here in winter, it would be enough to leave a mold sitting out for a few weeks to fully dry!), or over 212F at any humidity.
              2. First chemical dehydration: when PoP sets, it forms a chemical dihydrate (it's the hydrating process that makes it set, which is also true of Portland cement -- which is why it makes such a bad choice for refractory). Up around 400F, it dehydrates to the hemihydrate ("half hydrate"), losing 75% of the chemically combined water.
              3. Second chemical dehydration: up around 1000F, the rest of the water is given up, resulting in straight-up calcium sulfate.
              4. Calcium sulfate itself decomposes above 2400F or so, giving off stinky SO2 gas (and potentially contaminating whatever metal is touching it), leaving lime (calcium oxide), if additives don't react first (for example, if silica is present, it'll start to form glass).

              If you're pouring a metal at a temperature less than 100F below the next dehydration point, you must calcine the mold at least past the preceeding stage. The mold does not necessarily have to be heated all the way to the pouring temperature.

              Examples:
              - Solder might not need a calcined mold at all. With a melting point around 350F, it's close (it might get bubbly), but may be achieved with only basic dehydration of the mold (say, 250F throughout?).

              - Lead and zinc can be cast comfortably in a mold baked out at 450F for several hours. Zinc is close, with a pouring temp of maybe 900F, close to the 1000F dehydration point. But as long as it isn't too hot, you need only complete the first dehydration to pour successfully.

              - Aluminum, and other nonferrous alloys like bronzes, with pouring temps over 1200F, require that the mold be calcined past 1000F (usually to the point where residual soot burns off, which is around red heat -- more than good enough). A very open mold might turn out passable with only the first stage, but don't count on it. (Once upon a time, I cast a pulley in a sand mold, forming the grooves with PoP core inserts. I had baked them thoroughly at 450F just before assembling the mold. The casting worked, but the grooves were obviously distorted by the steam given off by that pesky half a hydration.)

              - Iron and steel cannot be poured in PoP molds because the stuff fully decomposes over 2500F (causing more gas, shrinkage and cracking), and the sulfurous gasses will react with iron to form sulfide impurities, which cause embrittlement.

              HTH,

              Tim

              --- In hobbicast@yahoogroups.com, "crashbone256" <wheezer606@...> wrote:
              >
              > Group:
              >
              > I made the mold from eps. I taped the edges with masking tape.
              > I encased the mold in POP. The mold was oven dried at 170 F for 12 hours.
              > Then 8 hours at 200 F. Acetone was poured into the mold the dissolve the
              > styrofoam. The mold was dried at 210 F for 3 hours. The 200F molds were buried in new dry sand to near the top.
              >
              > 5 # Al muffins were melted in a 10 # crucible. The crux was red hot when removed.
              >
              > As the Al melt was poured into the "empty" mold it bubbled and popped and blew
              > bubbles up through the sprue. A steady stream was being poured, but it didn't want to go down the sprue.
              >
              > You can see from the first picture how it was gated.
              > Sprued on the top, Al runs down into the mold and rises off the bottom.
              >
              > The casting is porous and crappy.
              > What to do next time?
              >
              >
              > Thanks
              > lance
              > ++++
              >
              >
              > http://groups.yahoo.com/group/hobbicast/photos/album/1891226731/pic/list
              >
            • David Hair
              I ve been reading the last few post about POP molds. HELP, what is POP. I guess you can tell I m green at this. DH ... From: tmoranwms
              Message 6 of 24 , Apr 10, 2013
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                I've been reading the last few post about POP molds.
                HELP, what is POP. I guess you can tell I'm green at this.

                DH
                ----- Original Message -----
                From: "tmoranwms" <tmoranwms@...>
                To: <hobbicast@yahoogroups.com>
                Sent: Wednesday, April 10, 2013 2:16 AM
                Subject: [hobbicast] Re: Need advice


                > PoP dries out in three stages:
                > 1. Absorbed moisture. This is mostly driven off at any temperature with
                > low humidity (with the dry air around here in winter, it would be enough
                > to leave a mold sitting out for a few weeks to fully dry!), or over 212F
                > at any humidity.
                > 2. First chemical dehydration: when PoP sets, it forms a chemical
                > dihydrate (it's the hydrating process that makes it set, which is also
                > true of Portland cement -- which is why it makes such a bad choice for
                > refractory). Up around 400F, it dehydrates to the hemihydrate ("half
                > hydrate"), losing 75% of the chemically combined water.
                > 3. Second chemical dehydration: up around 1000F, the rest of the water is
                > given up, resulting in straight-up calcium sulfate.
                > 4. Calcium sulfate itself decomposes above 2400F or so, giving off stinky
                > SO2 gas (and potentially contaminating whatever metal is touching it),
                > leaving lime (calcium oxide), if additives don't react first (for example,
                > if silica is present, it'll start to form glass).
                >
                > If you're pouring a metal at a temperature less than 100F below the next
                > dehydration point, you must calcine the mold at least past the preceeding
                > stage. The mold does not necessarily have to be heated all the way to the
                > pouring temperature.
                >
                > Examples:
                > - Solder might not need a calcined mold at all. With a melting point
                > around 350F, it's close (it might get bubbly), but may be achieved with
                > only basic dehydration of the mold (say, 250F throughout?).
                >
                > - Lead and zinc can be cast comfortably in a mold baked out at 450F for
                > several hours. Zinc is close, with a pouring temp of maybe 900F, close to
                > the 1000F dehydration point. But as long as it isn't too hot, you need
                > only complete the first dehydration to pour successfully.
                >
                > - Aluminum, and other nonferrous alloys like bronzes, with pouring temps
                > over 1200F, require that the mold be calcined past 1000F (usually to the
                > point where residual soot burns off, which is around red heat -- more than
                > good enough). A very open mold might turn out passable with only the
                > first stage, but don't count on it. (Once upon a time, I cast a pulley in
                > a sand mold, forming the grooves with PoP core inserts. I had baked them
                > thoroughly at 450F just before assembling the mold. The casting worked,
                > but the grooves were obviously distorted by the steam given off by that
                > pesky half a hydration.)
                >
                > - Iron and steel cannot be poured in PoP molds because the stuff fully
                > decomposes over 2500F (causing more gas, shrinkage and cracking), and the
                > sulfurous gasses will react with iron to form sulfide impurities, which
                > cause embrittlement.
                >
                > HTH,
                >
                > Tim
                >
                > --- In hobbicast@yahoogroups.com, "crashbone256" <wheezer606@...> wrote:
                >>
                >> Group:
                >>
                >> I made the mold from eps. I taped the edges with masking tape.
                >> I encased the mold in POP. The mold was oven dried at 170 F for 12 hours.
                >> Then 8 hours at 200 F. Acetone was poured into the mold the dissolve the
                >> styrofoam. The mold was dried at 210 F for 3 hours. The 200F molds were
                >> buried in new dry sand to near the top.
                >>
                >> 5 # Al muffins were melted in a 10 # crucible. The crux was red hot when
                >> removed.
                >>
                >> As the Al melt was poured into the "empty" mold it bubbled and popped and
                >> blew
                >> bubbles up through the sprue. A steady stream was being poured, but it
                >> didn't want to go down the sprue.
                >>
                >> You can see from the first picture how it was gated.
                >> Sprued on the top, Al runs down into the mold and rises off the bottom.
                >>
                >> The casting is porous and crappy.
                >> What to do next time?
                >>
                >>
                >> Thanks
                >> lance
                >> ++++
                >>
                >>
                >> http://groups.yahoo.com/group/hobbicast/photos/album/1891226731/pic/list
                >>
                >
                >
                >
                >
                > ------------------------------------
                >
                > For discussion of Metal Casting and related issues
                > this list does not accept attachments.
                >
                > Files area and list services are at:
                > http://groups.yahoo.com/group/hobbicast
                >
                > For additional files and photos and off topic discussions
                > check out these two affiliated sites:
                > http://groups.yahoo.com/group/sandcrabs
                > http://groups.yahoo.com/group/Hobbicast1
                >
                > Please visit our sponsor: Budget Casting Supply
                > http://budgetcastingsupply.com/
                >
                > List Owner:
                > owly@...
                >
                > Yahoo! Groups Links
                >
                >
                >
                >
                > -----
                > No virus found in this message.
                > Checked by AVG - www.avg.com
                > Version: 2013.0.3272 / Virus Database: 3162/6235 - Release Date: 04/09/13
                >
              • Ron Thompson
                ... Plaster Of Paris. -- Ron Thompson On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA Think, Draw, Print. 3D printers ROCK!
                Message 7 of 24 , Apr 10, 2013
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                  On 4/10/2013 3:54 AM, David Hair wrote:
                  > I've been reading the last few post about POP molds.
                  > HELP, what is POP. I guess you can tell I'm green at this.
                  >
                  > DH
                  > ----- Original Message -----
                  > From: "tmoranwms" <tmoranwms@... <mailto:tmoranwms%40charter.net>>
                  > To: <hobbicast@yahoogroups.com <mailto:hobbicast%40yahoogroups.com>>
                  > Sent: Wednesday, April 10, 2013 2:16 AM
                  > Subject: [hobbicast] Re: Need advice
                  >
                  > > PoP dries out in three stages:
                  Plaster Of Paris.

                  --


                  Ron Thompson
                  On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA

                  Think, Draw, Print. 3D printers ROCK!

                  http://www.plansandprojects.com/My%20Machines/PrusaMendel2012-1/

                  http://www.plansandprojects.com My hobby pages are here:
                  http://www.plansandprojects.com/My%20Machines/

                  Visit the castinghobby FAQ:
                  http://castinghobbyfaq.bareboogerhost.com/








                  [Non-text portions of this message have been removed]
                • Dennis
                  Good recap of the process. Here is the a manufactures description http://www.gp.com/build/product.aspx?pid=1569 I have poured zinc (900 degree) into POP
                  Message 8 of 24 , Apr 10, 2013
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                    Good recap of the process. Here is the a manufactures' description
                    http://www.gp.com/build/product.aspx?pid=1569 I have poured zinc (900
                    degree) into POP molds that were dried in the kitchen oven.

                    Dennis Cranston
                    Houston, Texas


                    -----Original Message-----
                    From: hobbicast@yahoogroups.com [mailto:hobbicast@yahoogroups.com] On Behalf
                    Of tmoranwms
                    Sent: Wednesday, April 10, 2013 1:17 AM
                    To: hobbicast@yahoogroups.com
                    Subject: [hobbicast] Re: Need advice

                    PoP dries out in three stages:
                    1. Absorbed moisture. This is mostly driven off at any temperature with low
                    humidity (with the dry air around here in winter, it would be enough to
                    leave a mold sitting out for a few weeks to fully dry!), or over 212F at any
                    humidity.
                    2. First chemical dehydration: when PoP sets, it forms a chemical dihydrate
                    (it's the hydrating process that makes it set, which is also true of
                    Portland cement -- which is why it makes such a bad choice for refractory).
                    Up around 400F, it dehydrates to the hemihydrate ("half hydrate"), losing
                    75% of the chemically combined water.
                    3. Second chemical dehydration: up around 1000F, the rest of the water is
                    given up, resulting in straight-up calcium sulfate.
                    4. Calcium sulfate itself decomposes above 2400F or so, giving off stinky
                    SO2 gas (and potentially contaminating whatever metal is touching it),
                    leaving lime (calcium oxide), if additives don't react first (for example,
                    if silica is present, it'll start to form glass).

                    If you're pouring a metal at a temperature less than 100F below the next
                    dehydration point, you must calcine the mold at least past the preceeding
                    stage. The mold does not necessarily have to be heated all the way to the
                    pouring temperature.

                    Examples:
                    - Solder might not need a calcined mold at all. With a melting point around
                    350F, it's close (it might get bubbly), but may be achieved with only basic
                    dehydration of the mold (say, 250F throughout?).

                    - Lead and zinc can be cast comfortably in a mold baked out at 450F for
                    several hours. Zinc is close, with a pouring temp of maybe 900F, close to
                    the 1000F dehydration point. But as long as it isn't too hot, you need only
                    complete the first dehydration to pour successfully.

                    - Aluminum, and other nonferrous alloys like bronzes, with pouring temps
                    over 1200F, require that the mold be calcined past 1000F (usually to the
                    point where residual soot burns off, which is around red heat -- more than
                    good enough). A very open mold might turn out passable with only the first
                    stage, but don't count on it. (Once upon a time, I cast a pulley in a sand
                    mold, forming the grooves with PoP core inserts. I had baked them
                    thoroughly at 450F just before assembling the mold. The casting worked, but
                    the grooves were obviously distorted by the steam given off by that pesky
                    half a hydration.)

                    - Iron and steel cannot be poured in PoP molds because the stuff fully
                    decomposes over 2500F (causing more gas, shrinkage and cracking), and the
                    sulfurous gasses will react with iron to form sulfide impurities, which
                    cause embrittlement.

                    HTH,

                    Tim

                    --- In hobbicast@yahoogroups.com, "crashbone256" <wheezer606@...> wrote:
                    >
                    > Group:
                    >
                    > I made the mold from eps. I taped the edges with masking tape.
                    > I encased the mold in POP. The mold was oven dried at 170 F for 12 hours.
                    > Then 8 hours at 200 F. Acetone was poured into the mold the dissolve
                    > the styrofoam. The mold was dried at 210 F for 3 hours. The 200F molds
                    were buried in new dry sand to near the top.
                    >
                    > 5 # Al muffins were melted in a 10 # crucible. The crux was red hot when
                    removed.
                    >
                    > As the Al melt was poured into the "empty" mold it bubbled and popped
                    > and blew bubbles up through the sprue. A steady stream was being poured,
                    but it didn't want to go down the sprue.
                    >
                    > You can see from the first picture how it was gated.
                    > Sprued on the top, Al runs down into the mold and rises off the bottom.
                    >
                    > The casting is porous and crappy.
                    > What to do next time?
                    >
                    >
                    > Thanks
                    > lance
                    > ++++
                    >
                    >
                    > http://groups.yahoo.com/group/hobbicast/photos/album/1891226731/pic/li
                    > st
                    >




                    ------------------------------------

                    For discussion of Metal Casting and related issues this list does not accept
                    attachments.

                    Files area and list services are at:
                    http://groups.yahoo.com/group/hobbicast

                    For additional files and photos and off topic discussions check out these
                    two affiliated sites:
                    http://groups.yahoo.com/group/sandcrabs
                    http://groups.yahoo.com/group/Hobbicast1

                    Please visit our sponsor: Budget Casting Supply
                    http://budgetcastingsupply.com/

                    List Owner:
                    owly@...

                    Yahoo! Groups Links
                  • Dan Brewer
                    On of the problems with using POP is that it is hygroscopic meaning that the material will never release all of the water trapped in its structure. It actually
                    Message 9 of 24 , Apr 10, 2013
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                      On of the problems with using POP is that it is hygroscopic meaning that
                      the material will never release all of the water trapped in its structure.
                      It actually will draw water out of the atmosphere . I would use a material
                      that when fired will vitrify and change to a substance that now will reject
                      water. American plaster makes casting plaster. 50 lbs goes for about
                      20USD . There are several others. Plaster of Paris is best left to the
                      art casting for statues.

                      Dan in Auburn


                      On Tue, Apr 9, 2013 at 10:07 PM, Eggleston Lance <wheezer606@...>wrote:

                      > **
                      >
                      >
                      > OK, will dry 400-700 F.
                      >
                      > Would it work better to fill from the bottom and
                      > vent at the top ?
                      >
                      > lance
                      > ++++
                      >
                      > On Apr 9, 2013, at 10:19 PM, Jeshua Lacock wrote:
                      >
                      > > Sounds like the POP had far too much water in it still.
                      > >
                      > > I would dry it out more around 400F. When I do lost plastic casting (a
                      > bit different of course) I heat the POP mold up to around 1000F...
                      >
                      > [Non-text portions of this message have been removed]
                      >
                      >
                      >


                      [Non-text portions of this message have been removed]
                    • Yvanwolvesbane
                      Hey there, folks- PoP I m familiar with. This is the first time I ve heard of American Plaster. Is it known by other names? What makes it different from PoP?
                      Message 10 of 24 , Apr 10, 2013
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                        Hey there, folks-
                        PoP I'm familiar with. This is the first time I've heard of American Plaster. Is it known by other names? What makes it different from PoP?

                        Mark Feldmann/
                        Yvan Wolvesbane

                        Pacifist with occasional lapses


                        On Apr 10, 2013, at 9:52 AM, Dan Brewer <danqualman@...> wrote:

                        > On of the problems with using POP is that it is hygroscopic meaning that
                        > the material will never release all of the water trapped in its structure.
                        > It actually will draw water out of the atmosphere . I would use a material
                        > that when fired will vitrify and change to a substance that now will reject
                        > water. American plaster makes casting plaster. 50 lbs goes for about
                        > 20USD . There are several others. Plaster of Paris is best left to the
                        > art casting for statues.
                        >
                        > Dan in Auburn
                        >
                        >
                        > On Tue, Apr 9, 2013 at 10:07 PM, Eggleston Lance <wheezer606@...>wrote:
                        >
                        >> **
                        >>
                        >>
                        >> OK, will dry 400-700 F.
                        >>
                        >> Would it work better to fill from the bottom and
                        >> vent at the top ?
                        >>
                        >> lance
                        >> ++++
                        >>
                        >> On Apr 9, 2013, at 10:19 PM, Jeshua Lacock wrote:
                        >>
                        >>> Sounds like the POP had far too much water in it still.
                        >>>
                        >>> I would dry it out more around 400F. When I do lost plastic casting (a
                        >> bit different of course) I heat the POP mold up to around 1000F...
                        >>
                        >> [Non-text portions of this message have been removed]
                        >>
                        >>
                        >>
                        >
                        >
                        > [Non-text portions of this message have been removed]
                        >
                        >
                        >
                        > ------------------------------------
                        >
                        > For discussion of Metal Casting and related issues
                        > this list does not accept attachments.
                        >
                        > Files area and list services are at:
                        > http://groups.yahoo.com/group/hobbicast
                        >
                        > For additional files and photos and off topic discussions
                        > check out these two affiliated sites:
                        > http://groups.yahoo.com/group/sandcrabs
                        > http://groups.yahoo.com/group/Hobbicast1
                        >
                        > Please visit our sponsor: Budget Casting Supply
                        > http://budgetcastingsupply.com/
                        >
                        > List Owner:
                        > owly@...
                        >
                        > Yahoo! Groups Links
                        >
                        >
                        >
                      • Inventor
                        Just a side thought: Did you de-gass before the pour? Grandpa Bill
                        Message 11 of 24 , Apr 10, 2013
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                          Just a side thought:
                          Did you de-gass before the pour?

                          Grandpa Bill

                          --- In hobbicast@yahoogroups.com, "crashbone256" <wheezer606@...> wrote:
                          >
                          > Group:
                          >
                          > I made the mold from eps. I taped the edges with masking tape.
                          > I encased the mold in POP. The mold was oven dried at 170 F for 12 hours.
                          > Then 8 hours at 200 F. Acetone was poured into the mold the dissolve the
                          > styrofoam. The mold was dried at 210 F for 3 hours. The 200F molds were buried in new dry sand to near the top.
                          >
                          > 5 # Al muffins were melted in a 10 # crucible. The crux was red hot when removed.
                          >
                          > As the Al melt was poured into the "empty" mold it bubbled and popped and blew
                          > bubbles up through the sprue. A steady stream was being poured, but it didn't want to go down the sprue.
                          >
                          > You can see from the first picture how it was gated.
                          > Sprued on the top, Al runs down into the mold and rises off the bottom.
                          >
                          > The casting is porous and crappy.
                          > What to do next time?
                          >
                          >
                          > Thanks
                          > lance
                          > ++++
                          >
                          >
                          > http://groups.yahoo.com/group/hobbicast/photos/album/1891226731/pic/list
                          >
                        • StoneTool
                          Mark: I think you misread.......... American Plaster is probably a company not a product. Though I wouldn t be surprised if during the Bush administration
                          Message 12 of 24 , Apr 10, 2013
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                            Mark:
                            I think you misread.......... American Plaster is probably a
                            company not a product. Though I wouldn't be surprised if during the
                            Bush administration when they were stirring up hatred against the French
                            for telling the truth, and going to such absurd lengths as renaming
                            everything with the word "French", if Plaster of Paris wasn't renamed
                            "American Plaster" along with the other childish nonsense that went on!

                            Howard

                            On 04/10/2013 09:42 AM, Yvanwolvesbane wrote:
                            > Hey there, folks-
                            > PoP I'm familiar with. This is the first time I've heard of American Plaster. Is it known by other names? What makes it different from PoP?
                            >
                            > Mark Feldmann/
                            > Yvan Wolvesbane
                            >
                            > Pacifist with occasional lapses
                            >
                            >
                            > On Apr 10, 2013, at 9:52 AM, Dan Brewer <danqualman@...> wrote:
                            >
                            >> On of the problems with using POP is that it is hygroscopic meaning that
                            >> the material will never release all of the water trapped in its structure.
                            >> It actually will draw water out of the atmosphere . I would use a material
                            >> that when fired will vitrify and change to a substance that now will reject
                            >> water. American plaster makes casting plaster. 50 lbs goes for about
                            >> 20USD . There are several others. Plaster of Paris is best left to the
                            >> art casting for statues.
                            >>
                            >> Dan in Auburn
                            >>
                            >>
                            >> On Tue, Apr 9, 2013 at 10:07 PM, Eggleston Lance <wheezer606@...>wrote:
                            >>
                            >>> **
                            >>>
                            >>>
                            >>> OK, will dry 400-700 F.
                            >>>
                            >>> Would it work better to fill from the bottom and
                            >>> vent at the top ?
                            >>>
                            >>> lance
                            >>> ++++
                            >>>
                            >>> On Apr 9, 2013, at 10:19 PM, Jeshua Lacock wrote:
                            >>>
                            >>>> Sounds like the POP had far too much water in it still.
                            >>>>
                            >>>> I would dry it out more around 400F. When I do lost plastic casting (a
                            >>> bit different of course) I heat the POP mold up to around 1000F...
                            >>>
                            >>> [Non-text portions of this message have been removed]
                            >>>
                            >>>
                            >>>
                            >>
                            >> [Non-text portions of this message have been removed]
                            >>
                            >>
                            >>
                            >> ------------------------------------
                            >>
                            >> For discussion of Metal Casting and related issues
                            >> this list does not accept attachments.
                            >>
                            >> Files area and list services are at:
                            >> http://groups.yahoo.com/group/hobbicast
                            >>
                            >> For additional files and photos and off topic discussions
                            >> check out these two affiliated sites:
                            >> http://groups.yahoo.com/group/sandcrabs
                            >> http://groups.yahoo.com/group/Hobbicast1
                            >>
                            >> Please visit our sponsor: Budget Casting Supply
                            >> http://budgetcastingsupply.com/
                            >>
                            >> List Owner:
                            >> owly@...
                            >>
                            >> Yahoo! Groups Links
                            >>
                            >>
                            >>
                            >
                            > ------------------------------------
                            >
                            > For discussion of Metal Casting and related issues
                            > this list does not accept attachments.
                            >
                            > Files area and list services are at:
                            > http://groups.yahoo.com/group/hobbicast
                            >
                            > For additional files and photos and off topic discussions
                            > check out these two affiliated sites:
                            > http://groups.yahoo.com/group/sandcrabs
                            > http://groups.yahoo.com/group/Hobbicast1
                            >
                            > Please visit our sponsor: Budget Casting Supply
                            > http://budgetcastingsupply.com/
                            >
                            > List Owner:
                            > owly@...
                            >
                            > Yahoo! Groups Links
                            >
                            >
                            >
                            >
                          • Dan Brewer
                            The big difference is that when fired the substrate will no longer adsorb any moisture. The term used to describe it is vitrification or to become like glass.
                            Message 13 of 24 , Apr 10, 2013
                            • 0 Attachment
                              The big difference is that when fired the substrate will no longer adsorb
                              any moisture. The term used to describe it is vitrification or to become
                              like glass.


                              On Wed, Apr 10, 2013 at 8:42 AM, Yvanwolvesbane <yvanwolvesbane222@...
                              > wrote:

                              > **
                              >
                              >
                              > Hey there, folks-
                              > PoP I'm familiar with. This is the first time I've heard of American
                              > Plaster. Is it known by other names? What makes it different from PoP?
                              >
                              > Mark Feldmann/
                              > Yvan Wolvesbane
                              >
                              > Pacifist with occasional lapses
                              >
                              >
                              > On Apr 10, 2013, at 9:52 AM, Dan Brewer <danqualman@...> wrote:
                              >
                              > > On of the problems with using POP is that it is hygroscopic meaning that
                              > > the material will never release all of the water trapped in its
                              > structure.
                              > > It actually will draw water out of the atmosphere . I would use a
                              > material
                              > > that when fired will vitrify and change to a substance that now will
                              > reject
                              > > water. American plaster makes casting plaster. 50 lbs goes for about
                              > > 20USD . There are several others. Plaster of Paris is best left to the
                              > > art casting for statues.
                              > >
                              > > Dan in Auburn
                              > >
                              > >
                              > > On Tue, Apr 9, 2013 at 10:07 PM, Eggleston Lance <wheezer606@...
                              > >wrote:
                              > >
                              > >> **
                              >
                              > >>
                              > >>
                              > >> OK, will dry 400-700 F.
                              > >>
                              > >> Would it work better to fill from the bottom and
                              > >> vent at the top ?
                              > >>
                              > >> lance
                              > >> ++++
                              > >>
                              > >> On Apr 9, 2013, at 10:19 PM, Jeshua Lacock wrote:
                              > >>
                              > >>> Sounds like the POP had far too much water in it still.
                              > >>>
                              > >>> I would dry it out more around 400F. When I do lost plastic casting (a
                              > >> bit different of course) I heat the POP mold up to around 1000F...
                              > >>
                              > >> [Non-text portions of this message have been removed]
                              > >>
                              > >>
                              > >>
                              > >
                              > >
                              > > [Non-text portions of this message have been removed]
                              > >
                              > >
                              > >
                              > > ------------------------------------
                              >
                              > >
                              > > For discussion of Metal Casting and related issues
                              > > this list does not accept attachments.
                              > >
                              > > Files area and list services are at:
                              > > http://groups.yahoo.com/group/hobbicast
                              > >
                              > > For additional files and photos and off topic discussions
                              > > check out these two affiliated sites:
                              > > http://groups.yahoo.com/group/sandcrabs
                              > > http://groups.yahoo.com/group/Hobbicast1
                              > >
                              > > Please visit our sponsor: Budget Casting Supply
                              > > http://budgetcastingsupply.com/
                              > >
                              > > List Owner:
                              > > owly@...
                              > >
                              > > Yahoo! Groups Links
                              > >
                              > >
                              > >
                              >
                              >
                              >


                              [Non-text portions of this message have been removed]
                            • Yvanwolvesbane
                              Thanks, Dan. That was very clear & warrants further investigation. Mark Feldmann/ Yvan Wolvesbane Pacifist ...with occasional lapses.
                              Message 14 of 24 , Apr 10, 2013
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                                Thanks, Dan. That was very clear & warrants further investigation.

                                Mark Feldmann/
                                Yvan Wolvesbane

                                Pacifist ...with occasional lapses.


                                On Apr 10, 2013, at 4:21 PM, Dan Brewer <danqualman@...> wrote:

                                > The big difference is that when fired the substrate will no longer adsorb
                                > any moisture. The term used to describe it is vitrification or to become
                                > like glass.
                                >>
                                >>
                                >>
                                >>
                                >>
                                >>
                                >>>
                                >>>
                                >>>
                                >>>>
                                >>>>
                                >>>>
                                >>>>
                                >>>>
                                >>>>>
                                >>>>
                                >>>>
                                >>>>
                                >>>>
                                >>>
                                >>>
                                >>>
                                >>>
                                >>>
                                >>>
                                >>>
                                >>>
                                >>>
                                >>>
                                >>>
                                >>>
                                >>>
                                >>>
                                >>
                                >>
                                >>
                              • Inventor
                                Hey Dan, About a half a dozen links wouldn t hurt.... A few to read up about it. A few more as to where to buy it for 20 BUCKS All I ve found was clay and
                                Message 15 of 24 , Apr 11, 2013
                                • 0 Attachment
                                  Hey Dan,
                                  About a half a dozen links wouldn't hurt....
                                  A few to read up about it.
                                  A few more as to where to buy it for "20 BUCKS"

                                  All I've found was clay and that 'started' at $85/50#.

                                  Grandpa Bill

                                  --- In hobbicast@yahoogroups.com, Dan Brewer <danqualman@...> wrote:
                                  >
                                  > On of the problems with using POP is that it is hygroscopic meaning that
                                  > the material will never release all of the water trapped in its structure.
                                  > It actually will draw water out of the atmosphere . I would use a material
                                  > that when fired will vitrify and change to a substance that now will reject
                                  > water. American plaster makes casting plaster. 50 lbs goes for about
                                  > 20USD . There are several others. Plaster of Paris is best left to the
                                  > art casting for statues.
                                  >
                                  > Dan in Auburn
                                • Dan Brewer
                                  So here is a link to one supplier. http://www.sheffield-pottery.com/U-S-Gypsum-1-CASTING-PLASTER-50-lbs-p/rmcaspla50.htm The name of the company is US gypsum
                                  Message 16 of 24 , Apr 11, 2013
                                  • 0 Attachment
                                    So here is a link to one supplier.
                                    http://www.sheffield-pottery.com/U-S-Gypsum-1-CASTING-PLASTER-50-lbs-p/rmcaspla50.htm
                                    The name of the company is US gypsum not US plaster. Brain fart. The way
                                    that I use it is to take my wax master with sprus and vent attached and
                                    coat it in Jet dry. Yes the stuff you use in your dish washer. It breaks
                                    the surface tension on the wax and allows the plaster to stick. I mix a
                                    little of the plaster up to the consistency of thin pancake batter and
                                    paint it on. until I have coated the entire master except the top of the
                                    pouring cup and the top of the vents. . I let that dry a little miz a
                                    little more up a little thicker and put on another coat. When still wet I
                                    sprinkle flint sand on the entire piece. Let that dry for a little. Mix up
                                    some more plaster about 60/40 plaster sand and coat the piece. Let dry. You
                                    should have coated the piece about 1.4 to 1/2 inch thick by now. Mix up
                                    some more plaster 50/50 sand and plaster. sprinkle each coat with sand. The
                                    next coat should be 30/30/30 plaster /sand / and grog. Grog is previously
                                    fired plaster that has been broken up in to pieces that will fit through a
                                    #8 sieve. When you have 3/4 to one inch of plaster wrap the piece in small
                                    chicken wire. This is to keep the mold from breaking up when you fire it.
                                    Add another inch of plaster , grog, sand to the outside of the mold. The
                                    top and bottom of the mold should be able to support the mold with out
                                    tipping over. The top because when you fire it the top will be down so all
                                    of the wax will leave the mold and the bottom so you can fill the now
                                    vacated mold with metal. Let dry .for several days in a warm spot. I place
                                    mine on a blotter board. My blotter board is a 2x2 piece of drywall.
                                    Place in your kiln and heat at the rate of 100 deg f per hour until the
                                    melting temp of the wax has been reached. My kiln has a stainless steel
                                    sink in the bottom that is plumbed out the bottom to get some of the wax
                                    out of the kiln. I am able to recover some of it but not much. after the
                                    wax is out around 200 to 275 deg you can ramp up a little faster Fire at
                                    2000deg f for 4 to 20 hours depending on size of the piece. Let cool to
                                    around 400 deg and pour.. Cover the pouring cup and vents with perlite or
                                    vermiculite and let cool. When the outside of the mold is just hot enough
                                    to touch sweep off the perlite/ vermiculite and you can remove the
                                    plaster. Remember that it will be hot. I use a hammer and a water hose to
                                    remove most of the plaster . Plaster will clog your drain . More clean up
                                    can be done with a stiff brush or sand blasting.
                                    For more information look up lost wax casting , ceramic shell casting.

                                    Dan in Auburn

                                    Other places to find casting plaster are pottery suppl houses. jewelery
                                    supply houses. And there are lots of formulas of the casting plaster. This
                                    is just the one that I have been using.


                                    On Thu, Apr 11, 2013 at 11:56 AM, Inventor <welfab@...> wrote:

                                    > **
                                    >
                                    >
                                    > Hey Dan,
                                    > About a half a dozen links wouldn't hurt....
                                    > A few to read up about it.
                                    > A few more as to where to buy it for "20 BUCKS"
                                    >
                                    > All I've found was clay and that 'started' at $85/50#.
                                    >
                                    > Grandpa Bill
                                    >
                                    >
                                    > --- In hobbicast@yahoogroups.com, Dan Brewer <danqualman@...> wrote:
                                    > >
                                    > > On of the problems with using POP is that it is hygroscopic meaning that
                                    > > the material will never release all of the water trapped in its
                                    > structure.
                                    > > It actually will draw water out of the atmosphere . I would use a
                                    > material
                                    > > that when fired will vitrify and change to a substance that now will
                                    > reject
                                    > > water. American plaster makes casting plaster. 50 lbs goes for about
                                    > > 20USD . There are several others. Plaster of Paris is best left to the
                                    > > art casting for statues.
                                    > >
                                    > > Dan in Auburn
                                    >
                                    >
                                    >


                                    [Non-text portions of this message have been removed]
                                  • abascirocco
                                    FWIW, US Gypsum also has a plaster specifically formulated for non-ferrous metal casting, they call it simply USG metal casting plaster. The other major North
                                    Message 17 of 24 , Apr 11, 2013
                                    • 0 Attachment
                                      FWIW, US Gypsum also has a plaster specifically formulated for non-ferrous metal casting, they call it simply USG metal casting plaster. The other major North American plaster manufacturer is Georgia Pacific, they also have a line of metal casting plasters.



                                      --- In hobbicast@yahoogroups.com, Dan Brewer <danqualman@...> wrote:
                                      >
                                      > So here is a link to one supplier.
                                      > http://www.sheffield-pottery.com/U-S-Gypsum-1-CASTING-PLASTER-50-lbs-p/rmcaspla50.htm
                                      > The name of the company is US gypsum not US plaster. Brain fart. The way
                                      > that I use it is to take my wax master with sprus and vent attached and
                                      > coat it in Jet dry. Yes the stuff you use in your dish washer. It breaks
                                      > the surface tension on the wax and allows the plaster to stick. I mix a
                                      > little of the plaster up to the consistency of thin pancake batter and
                                      > paint it on. until I have coated the entire master except the top of the
                                      > pouring cup and the top of the vents. . I let that dry a little miz a
                                      > little more up a little thicker and put on another coat. When still wet I
                                      > sprinkle flint sand on the entire piece. Let that dry for a little. Mix up
                                      > some more plaster about 60/40 plaster sand and coat the piece. Let dry. You
                                      > should have coated the piece about 1.4 to 1/2 inch thick by now. Mix up
                                      > some more plaster 50/50 sand and plaster. sprinkle each coat with sand. The
                                      > next coat should be 30/30/30 plaster /sand / and grog. Grog is previously
                                      > fired plaster that has been broken up in to pieces that will fit through a
                                      > #8 sieve. When you have 3/4 to one inch of plaster wrap the piece in small
                                      > chicken wire. This is to keep the mold from breaking up when you fire it.
                                      > Add another inch of plaster , grog, sand to the outside of the mold. The
                                      > top and bottom of the mold should be able to support the mold with out
                                      > tipping over. The top because when you fire it the top will be down so all
                                      > of the wax will leave the mold and the bottom so you can fill the now
                                      > vacated mold with metal. Let dry .for several days in a warm spot. I place
                                      > mine on a blotter board. My blotter board is a 2x2 piece of drywall.
                                      > Place in your kiln and heat at the rate of 100 deg f per hour until the
                                      > melting temp of the wax has been reached. My kiln has a stainless steel
                                      > sink in the bottom that is plumbed out the bottom to get some of the wax
                                      > out of the kiln. I am able to recover some of it but not much. after the
                                      > wax is out around 200 to 275 deg you can ramp up a little faster Fire at
                                      > 2000deg f for 4 to 20 hours depending on size of the piece. Let cool to
                                      > around 400 deg and pour.. Cover the pouring cup and vents with perlite or
                                      > vermiculite and let cool. When the outside of the mold is just hot enough
                                      > to touch sweep off the perlite/ vermiculite and you can remove the
                                      > plaster. Remember that it will be hot. I use a hammer and a water hose to
                                      > remove most of the plaster . Plaster will clog your drain . More clean up
                                      > can be done with a stiff brush or sand blasting.
                                      > For more information look up lost wax casting , ceramic shell casting.
                                      >
                                      > Dan in Auburn
                                      >
                                      > Other places to find casting plaster are pottery suppl houses. jewelery
                                      > supply houses. And there are lots of formulas of the casting plaster. This
                                      > is just the one that I have been using.
                                      >
                                      >
                                      > On Thu, Apr 11, 2013 at 11:56 AM, Inventor <welfab@...> wrote:
                                      >
                                      > > **
                                      > >
                                      > >
                                      > > Hey Dan,
                                      > > About a half a dozen links wouldn't hurt....
                                      > > A few to read up about it.
                                      > > A few more as to where to buy it for "20 BUCKS"
                                      > >
                                      > > All I've found was clay and that 'started' at $85/50#.
                                      > >
                                      > > Grandpa Bill
                                      > >
                                      > >
                                      > > --- In hobbicast@yahoogroups.com, Dan Brewer <danqualman@> wrote:
                                      > > >
                                      > > > On of the problems with using POP is that it is hygroscopic meaning that
                                      > > > the material will never release all of the water trapped in its
                                      > > structure.
                                      > > > It actually will draw water out of the atmosphere . I would use a
                                      > > material
                                      > > > that when fired will vitrify and change to a substance that now will
                                      > > reject
                                      > > > water. American plaster makes casting plaster. 50 lbs goes for about
                                      > > > 20USD . There are several others. Plaster of Paris is best left to the
                                      > > > art casting for statues.
                                      > > >
                                      > > > Dan in Auburn
                                      > >
                                      > >
                                      > >
                                      >
                                      >
                                      > [Non-text portions of this message have been removed]
                                      >
                                    • bs190815
                                      For years I have been using Ransom & Randoph Ultra-Vest. I recently bought five 100 pound drum; I use nothing else! Here is their web site, lots of good
                                      Message 18 of 24 , Apr 18, 2013
                                      • 0 Attachment
                                        For years I have been using Ransom & Randoph Ultra-Vest. I recently bought five 100 pound drum; I use nothing else!

                                        Here is their web site, lots of good information.

                                        http://www.ransom-randolph.com/
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