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Re: [hobbicast] sodium silicate for stabilizing rock

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  • giesser@aol.com
    What you really need is Colloidal Silica. This is a dispersion of Silicon Dioxide in water. When dried, it creates a solid glass that is not water soluble. If
    Message 1 of 16 , May 22 12:46 PM
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      What you really need is Colloidal Silica. This is a dispersion of Silicon Dioxide in water. When dried, it creates a solid glass that is not water soluble.

      If you use Sodium Silicate, mix in some -200 mesh Silica as a filler. This will help to improve the water resistance.
      Sent from my Verizon Wireless BlackBerry

      -----Original Message-----
      From: Stone Tool <owly@...>
      Date: Sat, 22 May 2010 10:08:25
      To: <hobbicast@yahoogroups.com>
      Subject: [hobbicast] sodium silicate for stabilizing rock

      My understanding is that sodium silicate when exposed to CO2 undergoes a
      transition to silicon dioxide.........and presumably sodium
      hydroxide...... reversing the reaction that produced it in the first
      place................ more or less.

      Any chemists here that can give some insights on this??


      I have been doing some lapidary stuff lately.......... which soon
      will also involve doing some lost wax casting of silver, but first, I
      have a problem with some of the turquoise I have been working with.
      The host rock (limonite) is quite punky and soft, and I also have some
      chalky variscite that I would like to experiment with..... It has no
      value as it is, but I brought some home from my rock collecting trip
      just to play with. At the moment I have a small container of sodium
      silicate on the stove top which I brought up to water boiling temp with
      the rock in it, and have allowed to cool slowly. My plan is to
      repeatedly heat and cool the sodium silicate and rocks to encourage the
      sodium silicate to penetrate well.

      Here's the problem........ What I am trying to do is harden and
      stabilize the rock........ Simply having dehydrated sodium silicate in
      the stone is not what I really want....I'm looking to end up with
      silica impregnating the stone. My thinking here is that perhaps I
      need to put the pieces in a pressure pot and apply CO2 to the still wet
      pieces for a time.......... Is this a reasonable approach? I am
      working with 40% solution, and having to add some water between heats to
      dissolve a skin that forms. I intend to continue the heating / cooling
      process a number of times, and then perhaps use an ordinary pressure
      cooker to pressure the stuff up with CO2 from my MIG bottle.........
      Perhaps up to around 20 PSI or so which should be well within the
      capacity of a pressure cooker. Later if It works decently, I will just
      use some hydraulic tubing with one welded end and a fitting, and another
      with an O-Ring seal so I can go to full bottle pressure safely...... I'm
      not comfortable with much pressure on something of aluminum.

      ............................ Thoughts please ;-)


      Howard



      [Non-text portions of this message have been removed]
    • Rod
      ... Howard I m not a chemist, but jewelry and lapidary is one of my diversions. You can see my video on lost wax casting on YouTube at
      Message 2 of 16 , May 22 1:13 PM
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        --- In hobbicast@yahoogroups.com, Stone Tool <owly@...> wrote:
        >
        > My understanding is that sodium silicate when exposed to CO2 undergoes a
        > transition to silicon dioxide.........and presumably sodium
        > hydroxide...... reversing the reaction that produced it in the first
        > place................ more or less.
        >
        > Any chemists here that can give some insights on this??
        >
        <snip>

        Howard

        I'm not a chemist, but jewelry and lapidary is one of my diversions. You can see my video on lost wax casting on YouTube at
        http://www.youtube.com/watch?v=MvOKy3Msa4I .

        One brew I'm aware is a mix of 330 water clear adhesive lapidary glue with acetone. Mix the 1/2 ounce hardner and 1/2 ounce resin in one pint of acetone THOROUGLY.

        Put the turquoise and this mix in an air tight jar for a week or two in a cool area, and stir every couple of days. Take the stones out and let them air dry for another week or two before grinding.

        The epoxy/acetone mixture should last a long time if kept in a tightly sealed container.

        Hope this helps.

        Rod
      • Stone Tool
        Dick: That is my thought also.......however sodium silicate is a large percentage of water........... I know from experience that water boils at very low
        Message 3 of 16 , May 22 8:27 PM
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          Dick:
          That is my thought also.......however sodium silicate is a large
          percentage of water........... I know from experience that water boils
          at very low temps under vacuum.... that after all is what my vacuum pump
          is for (refrigeration). Experience shows that if there is moisture
          present, you don't achieve a really good vacuum..... but perhaps it is
          unnecessary.
          The other thing that comes to mind is radical pressure changes....
          supposing I had a chamber where I could rapidly change pressure from
          several thousand psig to 0 psig, and back again in a series of
          cycles..... the changing pressures would drive the fluid in and out of
          the porous stone......and out again bringing air with it each time it
          came out.. It would actually be fairly easy to do........ Perhaps
          pressure, followed by vacuum and purge.... vacuum to expand the bubbles
          and encourage them to come out of solution..... purge to remove the air,
          and then pressure to drive the fluid in..... etc....... It wouldn't of
          course really be "rapid" except perhaps for pressure release.


          Howard

          Dick Morris wrote:
          > At 08:08 AM 5/22/2010, you wrote:
          >
          >
          >> My plan is to
          >> repeatedly heat and cool the sodium silicate and rocks to encourage the
          >> sodium silicate to penetrate well.
          >>
          >
          > I have a good vacuum pump so I tend to think in terms of removing the
          > air, other gasses, and water with a vacuum and then let atmospheric
          > pressure force the liquid back into whatever I'm working on.
          >
          >
          >
          > Dick Morris
          > Anchorage, Alaska
          >
          >
          >
          > ------------------------------------
          >
          > 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
          >
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          > http://budgetcastingsupply.com/
          >
          > List Owner:
          > owly@...
          >
          > Yahoo! Groups Links
          >
          >
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          >
        • sonny djatnikasundjaja
            To harden sodium silicate, it is not necessary use pressure or vacuum with carbon dioxide. You can use ferro-silicon powder with/without mollases. The
          Message 4 of 16 , May 22 8:37 PM
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            To harden sodium silicate, it is not necessary use pressure or vacuum with carbon dioxide.
            You can use ferro-silicon powder with/without mollases. The process slower than carbon dioxide blows.

            Sonny
             

            --- On Sun, 23/5/10, Stone Tool <owly@...> wrote:

            From: Stone Tool <owly@...>
            Subject: Re: [hobbicast] sodium silicate for stabilizing rock
            To: hobbicast@yahoogroups.com
            Date: Sunday, 23 May, 2010, 10:27 AM







             









            Dick:

            That is my thought also.......however sodium silicate is a large

            percentage of water........... I know from experience that water boils

            at very low temps under vacuum.... that after all is what my vacuum pump

            is for (refrigeration). Experience shows that if there is moisture

            present, you don't achieve a really good vacuum..... but perhaps it is

            unnecessary.

            The other thing that comes to mind is radical pressure changes....

            supposing I had a chamber where I could rapidly change pressure from

            several thousand psig to 0 psig, and back again in a series of

            cycles..... the changing pressures would drive the fluid in and out of

            the porous stone......and out again bringing air with it each time it

            came out.. It would actually be fairly easy to do........ Perhaps

            pressure, followed by vacuum and purge.... vacuum to expand the bubbles

            and encourage them to come out of solution..... purge to remove the air,

            and then pressure to drive the fluid in..... etc....... It wouldn't of

            course really be "rapid" except perhaps for pressure release.



            Howard



            Dick Morris wrote:

            > At 08:08 AM 5/22/2010, you wrote:

            >

            >

            >> My plan is to

            >> repeatedly heat and cool the sodium silicate and rocks to encourage the

            >> sodium silicate to penetrate well.

            >>

            >

            > I have a good vacuum pump so I tend to think in terms of removing the

            > air, other gasses, and water with a vacuum and then let atmospheric

            > pressure force the liquid back into whatever I'm working on.

            >

            >

            >

            > Dick Morris

            > Anchorage, Alaska

            >

            >

            >

            > ------------------------------------

            >

            > 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]
          • Stone Tool
            Rod: I will save this along with a number of other suggestions........ My desire it to get away from things like epoxy... hence the interest in sodium
            Message 5 of 16 , May 22 8:47 PM
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              Rod:
              I will save this along with a number of other suggestions........
              My desire it to get away from things like epoxy... hence the interest
              in sodium silicate. Hardened sodium silicate should be virtually
              indistinguishable from silica based rock..... Though turquoise is
              alumina based. The object here is to stabilize the host rock... the
              turquoise itself is good material. Host rock is what they are calling
              limonite........ presumably a calcium based rock related to limestone.


              Howard

              Rod wrote:
              >
              >
              >
              > --- In hobbicast@yahoogroups.com, Stone Tool <owly@...> wrote:
              >
              >> My understanding is that sodium silicate when exposed to CO2 undergoes a
              >> transition to silicon dioxide.........and presumably sodium
              >> hydroxide...... reversing the reaction that produced it in the first
              >> place................ more or less.
              >>
              >> Any chemists here that can give some insights on this??
              >>
              >>
              > <snip>
              >
              > Howard
              >
              > I'm not a chemist, but jewelry and lapidary is one of my diversions. You can see my video on lost wax casting on YouTube at
              > http://www.youtube.com/watch?v=MvOKy3Msa4I .
              >
              > One brew I'm aware is a mix of 330 water clear adhesive lapidary glue with acetone. Mix the 1/2 ounce hardner and 1/2 ounce resin in one pint of acetone THOROUGLY.
              >
              > Put the turquoise and this mix in an air tight jar for a week or two in a cool area, and stir every couple of days. Take the stones out and let them air dry for another week or two before grinding.
              >
              > The epoxy/acetone mixture should last a long time if kept in a tightly sealed container.
              >
              > Hope this helps.
              >
              > Rod
              >
              >
              >
              > ------------------------------------
              >
              > 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
              >
              >
              >
              >
              >
            • giesser@aol.com
              To harden sodium Silicate, all you need to do is dehydrate it. Tom Cobett From Denali, AK Sent from my Verizon Wireless BlackBerry ... From: sonny
              Message 6 of 16 , May 22 9:06 PM
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                To harden sodium Silicate, all you need to do is dehydrate it.

                Tom Cobett
                From Denali, AK
                Sent from my Verizon Wireless BlackBerry

                -----Original Message-----
                From: sonny djatnikasundjaja <sundadjaja@...>
                Date: Sat, 22 May 2010 20:37:48
                To: <hobbicast@yahoogroups.com>
                Subject: Re: [hobbicast] sodium silicate for stabilizing rock

                 
                To harden sodium silicate, it is not necessary use pressure or vacuum with carbon dioxide.
                You can use ferro-silicon powder with/without mollases. The process slower than carbon dioxide blows.

                Sonny
                 

                --- On Sun, 23/5/10, Stone Tool <owly@...> wrote:

                From: Stone Tool <owly@...>
                Subject: Re: [hobbicast] sodium silicate for stabilizing rock
                To: hobbicast@yahoogroups.com
                Date: Sunday, 23 May, 2010, 10:27 AM







                 









                Dick:

                That is my thought also.......however sodium silicate is a large

                percentage of water........... I know from experience that water boils

                at very low temps under vacuum.... that after all is what my vacuum pump

                is for (refrigeration). Experience shows that if there is moisture

                present, you don't achieve a really good vacuum..... but perhaps it is

                unnecessary.

                The other thing that comes to mind is radical pressure changes....

                supposing I had a chamber where I could rapidly change pressure from

                several thousand psig to 0 psig, and back again in a series of

                cycles..... the changing pressures would drive the fluid in and out of

                the porous stone......and out again bringing air with it each time it

                came out.. It would actually be fairly easy to do........ Perhaps

                pressure, followed by vacuum and purge.... vacuum to expand the bubbles

                and encourage them to come out of solution..... purge to remove the air,

                and then pressure to drive the fluid in..... etc....... It wouldn't of

                course really be "rapid" except perhaps for pressure release.



                Howard



                Dick Morris wrote:

                > At 08:08 AM 5/22/2010, you wrote:

                >

                >

                >> My plan is to

                >> repeatedly heat and cool the sodium silicate and rocks to encourage the

                >> sodium silicate to penetrate well.

                >>

                >

                > I have a good vacuum pump so I tend to think in terms of removing the

                > air, other gasses, and water with a vacuum and then let atmospheric

                > pressure force the liquid back into whatever I'm working on.

                >

                >

                >

                > Dick Morris

                > Anchorage, Alaska

                >

                >

                >

                > ------------------------------------

                >

                > 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]



                [Non-text portions of this message have been removed]
              • Alan Millar
                ... Boy, did I learn that last week! My friends and I are making a Gingery lathe in cast iron, and we used sodium silicate and olivine sand to make cores for
                Message 7 of 16 , May 23 10:33 AM
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                  On May 22, 2010, at 9:06 PM, giesser@... wrote:
                  > To harden sodium Silicate, all you need to do is dehydrate it.
                  >
                  Boy, did I learn that last week! My friends and I are making a
                  Gingery lathe in cast iron, and we used sodium silicate and olivine
                  sand to make cores for the lathe bed.

                  After we poured the iron, the cores would not come out. I drilled
                  out most of them with a masonry bit on a hammer drill. We tried
                  using a pressure washer to blast the rest of it out, and it did not
                  touch it. We cut a groove in the asphalt driveway (accidentally)
                  with the pressure washer, but it did not affect the sodium silicate/
                  sand at all. It was bonded to the surface of the casting.

                  It definitely turned into rock, and sure did not dissolve in water.
                  An interesting learning experience :-)

                  - Alan
                • bs190815
                  What you need is the Sodium Silicate that is specifically manufactured for foundry use. They add starches and sugars to the SS so that upon heating with the
                  Message 8 of 16 , May 24 6:39 PM
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                    What you need is the Sodium Silicate that is specifically manufactured for foundry use. They add starches and sugars to the SS so that upon heating with the poured metal, it disintegrates. I use a SS made by Ashland Chem." Adcosil NF". They no longer make it, but I have enough left to do my castings. There are several who sell SS Binders, here is one:

                    http://foseco-foundry.com/Products-Services/Products/Sand-Binders.html

                    --- In hobbicast@yahoogroups.com, Alan Millar <amillar503@...> wrote:
                    >
                    > On May 22, 2010, at 9:06 PM, giesser@... wrote:
                    > > To harden sodium Silicate, all you need to do is dehydrate it.
                    > >
                    > Boy, did I learn that last week! My friends and I are making a
                    > Gingery lathe in cast iron, and we used sodium silicate and olivine
                    > sand to make cores for the lathe bed.
                    >
                    > After we poured the iron, the cores would not come out. I drilled
                    > out most of them with a masonry bit on a hammer drill. We tried
                    > using a pressure washer to blast the rest of it out, and it did not
                    > touch it. We cut a groove in the asphalt driveway (accidentally)
                    > with the pressure washer, but it did not affect the sodium silicate/
                    > sand at all. It was bonded to the surface of the casting.
                    >
                    > It definitely turned into rock, and sure did not dissolve in water.
                    > An interesting learning experience :-)
                    >
                    > - Alan
                    >
                  • bcjohn48
                    Alan: I hope someone has an answer to your problem, because I have the same one. However, it seems if I used a lot (not sure what a lot might be) of SS the
                    Message 9 of 16 , May 25 7:41 AM
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                      Alan:

                      I hope someone has an answer to your problem, because I have the same one. However, it seems if I used a lot (not sure what a lot might be) of SS the core comes out really hard, if I back off on the SS and use a softer core, it come out easier. But really, I haven't a clue.

                      Bob

                      --- In hobbicast@yahoogroups.com, Alan Millar <amillar503@...> wrote:
                      >
                      > On May 22, 2010, at 9:06 PM, giesser@... wrote:
                      > > To harden sodium Silicate, all you need to do is dehydrate it.
                      > >
                      > Boy, did I learn that last week! My friends and I are making a
                      > Gingery lathe in cast iron, and we used sodium silicate and olivine
                      > sand to make cores for the lathe bed.
                      >
                      > After we poured the iron, the cores would not come out. I drilled
                      > out most of them with a masonry bit on a hammer drill. We tried
                      > using a pressure washer to blast the rest of it out, and it did not
                      > touch it. We cut a groove in the asphalt driveway (accidentally)
                      > with the pressure washer, but it did not affect the sodium silicate/
                      > sand at all. It was bonded to the surface of the casting.
                      >
                      > It definitely turned into rock, and sure did not dissolve in water.
                      > An interesting learning experience :-)
                      >
                      > - Alan
                      >
                    • michael.a.porter@comcast.net
                      Have you tried steam? ... From: Alan Millar To: hobbicast@yahoogroups.com Sent: Sun, 23 May 2010 17:33:47 +0000 (UTC) Subject: Re: [hobbicast] sodium silicate
                      Message 10 of 16 , May 25 5:26 PM
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                        Have you tried steam?

                        ----- Original Message -----
                        From: Alan Millar
                        To: hobbicast@yahoogroups.com
                        Sent: Sun, 23 May 2010 17:33:47 +0000 (UTC)
                        Subject: Re: [hobbicast] sodium silicate for stabilizing rock













                        On May 22, 2010, at 9:06 PM, giesser@... wrote:


                        > To harden sodium Silicate, all you need to do is dehydrate it.


                        >


                        Boy, did I learn that last week! My friends and I are making a


                        Gingery lathe in cast iron, and we used sodium silicate and olivine


                        sand to make cores for the lathe bed.



                        After we poured the iron, the cores would not come out. I drilled


                        out most of them with a masonry bit on a hammer drill. We tried


                        using a pressure washer to blast the rest of it out, and it did not


                        touch it. We cut a groove in the asphalt driveway (accidentally)


                        with the pressure washer, but it did not affect the sodium silicate/


                        sand at all. It was bonded to the surface of the casting.



                        It definitely turned into rock, and sure did not dissolve in water.


                        An interesting learning experience :-)



                        - Alan








                        [Non-text portions of this message have been removed]
                      • Dan Brewer
                        You need to add some thing that will burn out or crush in the mixture. The big boys use a corn syrup additive in the mix. It allows the core to be reused.
                        Message 11 of 16 , May 25 6:45 PM
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                          You need to add some thing that will burn out or crush in the mixture. The
                          big boys use a corn syrup additive in the mix. It allows the core to be
                          reused.
                          And it releases from the casting.

                          Just a thought.

                          Dan in Auburn

                          On Tue, May 25, 2010 at 5:26 PM, <michael.a.porter@...> wrote:

                          >
                          >
                          > Have you tried steam?
                          >
                          >
                          > ----- Original Message -----
                          > From: Alan Millar
                          > To: hobbicast@yahoogroups.com <hobbicast%40yahoogroups.com>
                          > Sent: Sun, 23 May 2010 17:33:47 +0000 (UTC)
                          > Subject: Re: [hobbicast] sodium silicate for stabilizing rock
                          >
                          > On May 22, 2010, at 9:06 PM, giesser@... <giesser%40aol.com> wrote:
                          >
                          > > To harden sodium Silicate, all you need to do is dehydrate it.
                          >
                          > >
                          >
                          > Boy, did I learn that last week! My friends and I are making a
                          >
                          > Gingery lathe in cast iron, and we used sodium silicate and olivine
                          >
                          > sand to make cores for the lathe bed.
                          >
                          > After we poured the iron, the cores would not come out. I drilled
                          >
                          > out most of them with a masonry bit on a hammer drill. We tried
                          >
                          > using a pressure washer to blast the rest of it out, and it did not
                          >
                          > touch it. We cut a groove in the asphalt driveway (accidentally)
                          >
                          > with the pressure washer, but it did not affect the sodium silicate/
                          >
                          > sand at all. It was bonded to the surface of the casting.
                          >
                          > It definitely turned into rock, and sure did not dissolve in water.
                          >
                          > An interesting learning experience :-)
                          >
                          > - Alan
                          >
                          > [Non-text portions of this message have been removed]
                          >
                          >
                          >


                          [Non-text portions of this message have been removed]
                        • giesser@aol.com
                          Corn syrup, molasses, sugar, starch and even flour will help with shake out. Use at 10 to 20% by weight of the Silicate. Use the Silicate at 3 to 5% by weight
                          Message 12 of 16 , May 26 1:00 PM
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                            Corn syrup, molasses, sugar, starch and even flour will help with shake out. Use at 10 to 20% by weight of the Silicate.

                            Use the Silicate at 3 to 5% by weight of the sand. The preferred Silicates are PQ Corp. RU or M Grade. You can add a little water to thin out the Silicates.
                            Sent from my Verizon Wireless BlackBerry

                            -----Original Message-----
                            From: Dan Brewer <danqualman@...>
                            Date: Tue, 25 May 2010 18:45:09
                            To: <hobbicast@yahoogroups.com>
                            Subject: Re: [hobbicast] sodium silicate for stabilizing rock

                            You need to add some thing that will burn out or crush in the mixture. The
                            big boys use a corn syrup additive in the mix. It allows the core to be
                            reused.
                            And it releases from the casting.

                            Just a thought.

                            Dan in Auburn

                            On Tue, May 25, 2010 at 5:26 PM, <michael.a.porter@...> wrote:

                            >
                            >
                            > Have you tried steam?
                            >
                            >
                            > ----- Original Message -----
                            > From: Alan Millar
                            > To: hobbicast@yahoogroups.com <hobbicast%40yahoogroups.com>
                            > Sent: Sun, 23 May 2010 17:33:47 +0000 (UTC)
                            > Subject: Re: [hobbicast] sodium silicate for stabilizing rock
                            >
                            > On May 22, 2010, at 9:06 PM, giesser@... <giesser%40aol.com> wrote:
                            >
                            > > To harden sodium Silicate, all you need to do is dehydrate it.
                            >
                            > >
                            >
                            > Boy, did I learn that last week! My friends and I are making a
                            >
                            > Gingery lathe in cast iron, and we used sodium silicate and olivine
                            >
                            > sand to make cores for the lathe bed.
                            >
                            > After we poured the iron, the cores would not come out. I drilled
                            >
                            > out most of them with a masonry bit on a hammer drill. We tried
                            >
                            > using a pressure washer to blast the rest of it out, and it did not
                            >
                            > touch it. We cut a groove in the asphalt driveway (accidentally)
                            >
                            > with the pressure washer, but it did not affect the sodium silicate/
                            >
                            > sand at all. It was bonded to the surface of the casting.
                            >
                            > It definitely turned into rock, and sure did not dissolve in water.
                            >
                            > An interesting learning experience :-)
                            >
                            > - Alan
                            >
                            > [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
                          • Dick Morris
                            Tom - Thanks again for all the info you have passed on. Just yesterday I tried a suggestion you posted several years ago of using corn starch and water as a
                            Message 13 of 16 , May 26 10:10 PM
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                              Tom - Thanks again for all the info you have passed on. Just
                              yesterday I tried a suggestion you posted several years ago of using
                              corn starch and water as a binder for cores. Formed in an Alumilite
                              RTV mold and zapped in the microwave. They worked great!



                              At 12:00 PM 5/26/2010, giesser@... wrote:
                              >Corn syrup, molasses, sugar, starch and even flour will help with
                              >shake out. Use at 10 to 20% by weight of the Silicate.
                              >

                              Dick Morris
                              Anchorage, Alaska
                            • englishfoundryman
                              Hi An alternative to sodium silicate as a sand binder is a blend of phosphate, silicate and borate. A commercial product exists marketed by Huettenes-Albertus
                              Message 14 of 16 , May 26 10:49 PM
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                                Hi

                                An alternative to sodium silicate as a sand binder is a blend of
                                phosphate, silicate and borate. A commercial product exists marketed by
                                Huettenes-Albertus called CORDIS. This was originally developed here in
                                the UK by the Pilkington firm.

                                The binder, which is inert and to my knowledge no environmental
                                penalties or odours has two fundemental benefits. It can be hot air
                                cured and is water soluble to give excellent decore. My only experience
                                is using it for aluminium castings 10 years ago.

                                There is a lot on the web about the product.

                                Best regards

                                Keith


                                --- In hobbicast@yahoogroups.com, Stone Tool <owly@...> wrote:
                                >
                                > My understanding is that sodium silicate when exposed to CO2 undergoes
                                a
                                > transition to silicon dioxide.........and presumably sodium
                                > hydroxide...... reversing the reaction that produced it in the first
                                > place................ more or less.
                                >
                                > Any chemists here that can give some insights on this??
                                >
                                >
                                > I have been doing some lapidary stuff lately.......... which soon
                                > will also involve doing some lost wax casting of silver, but first, I
                                > have a problem with some of the turquoise I have been working with.
                                > The host rock (limonite) is quite punky and soft, and I also have some
                                > chalky variscite that I would like to experiment with..... It has no
                                > value as it is, but I brought some home from my rock collecting trip
                                > just to play with. At the moment I have a small container of sodium
                                > silicate on the stove top which I brought up to water boiling temp
                                with
                                > the rock in it, and have allowed to cool slowly. My plan is to
                                > repeatedly heat and cool the sodium silicate and rocks to encourage
                                the
                                > sodium silicate to penetrate well.
                                >
                                > Here's the problem........ What I am trying to do is harden and
                                > stabilize the rock........ Simply having dehydrated sodium silicate in
                                > the stone is not what I really want....I'm looking to end up with
                                > silica impregnating the stone. My thinking here is that perhaps I
                                > need to put the pieces in a pressure pot and apply CO2 to the still
                                wet
                                > pieces for a time.......... Is this a reasonable approach? I am
                                > working with 40% solution, and having to add some water between heats
                                to
                                > dissolve a skin that forms. I intend to continue the heating /
                                cooling
                                > process a number of times, and then perhaps use an ordinary pressure
                                > cooker to pressure the stuff up with CO2 from my MIG bottle.........
                                > Perhaps up to around 20 PSI or so which should be well within the
                                > capacity of a pressure cooker. Later if It works decently, I will
                                just
                                > use some hydraulic tubing with one welded end and a fitting, and
                                another
                                > with an O-Ring seal so I can go to full bottle pressure safely......
                                I'm
                                > not comfortable with much pressure on something of aluminum.
                                >
                                > ............................ Thoughts please ;-)
                                >
                                >
                                > Howard
                                >
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