Loading ...
Sorry, an error occurred while loading the content.

Re: [hobbicast] Plaster Moulds for Brass

Expand Messages
  • Peter Sibley
    Do you think that system could be modified to use a thinner plaster coat , say 10 or 12 mm ( 3/8 or 1/2 ) then backed up by vibrated sand? It would speed the
    Message 1 of 7 , Aug 2, 2004
    • 0 Attachment
      Do you think that system could be modified to use a thinner plaster coat ,
      say 10 or 12 mm ( 3/8" or 1/2") then backed up by vibrated sand? It would
      speed the whole process up .
      Peter Sibley

      ----- Original Message -----
      From: "Brewer" <brewer@...>
      To: <hobbicast@yahoogroups.com>
      Sent: Tuesday, August 03, 2004 10:50 AM
      Subject: RE: [hobbicast] Plaster Moulds for Brass


      > Take a look at this site. She uses plaster to invest the wax in .
      Remember
      > that you need to fire the plaster and have it at temp before you poor.
      Any
      > moisture in the mold will cause an explosion.
      > http://www.stonefire.biz/index.php?page=gallery&gid=13
      > Dan in Auburn
      > -----Original Message-----
      > From: uscg_e7 [mailto:uscg_e7@...]
      > Sent: Monday, August 02, 2004 9:30 AM
      > To: hobbicast@yahoogroups.com
      > Subject: [hobbicast] Plaster Moulds for Brass
      >
      > Can I use a plaster mould for casting brass?
      >
      >
      >
      >
      > This list is for discussion of metal casting
      > and does not accept attachments. For off topic discussion and to share
      > photos and stuff: join Sandcrabs by sending a blank message to:
      > sandcrabs-subscribe@yahoogroups.com
      > http://groups.yahoo.com/group/sandcrabs
      > Please visit our sponsor: Budget Casting Supply
      > http://budgetcastingsupply.com/
      >
      > Files area and list services are at:
      > http://groups.yahoo.com/group/hobbicast For problems that cannot be
      > otherwise solved contact the list owner by email:
      > owly@...
      >
      >
      > Yahoo! Groups Links
      >
      >
      >
      >
      >
      >
      >
      > This list is for discussion of metal casting
      > and does not accept attachments. For off topic discussion and to share
      photos and stuff: join Sandcrabs by sending a blank message to:
      sandcrabs-subscribe@yahoogroups.com
      > http://groups.yahoo.com/group/sandcrabs
      > Please visit our sponsor: Budget Casting Supply
      > http://budgetcastingsupply.com/
      >
      > Files area and list services are at:
      > http://groups.yahoo.com/group/hobbicast For problems that cannot be
      otherwise solved contact the list owner by email:
      > owly@...
      >
      >
      > Yahoo! Groups Links
      >
      >
      >
      >
      >
      >
    • James Walker
      For about 12 years I lost-wax cast brass, bronze and a little fine silver with a mixture of 1 part fine silica sand, 1 part water and 1 part casting plaster.
      Message 2 of 7 , Aug 2, 2004
      • 0 Attachment
        For about 12 years I lost-wax cast brass, bronze and a little fine silver with a mixture of 1 part fine silica sand, 1 part water and 1 part casting plaster. It worked well for me, holding up well after steaming the wax out, baking and pouring the metal. Of course, you only get one copy, which was OK with me, since I was casting one-of-a-kind art objects.

        -Jim Walker


        James R. Walker, Metalsmith
        Specializing in fine metal repair, restoration, preservation
        Website: <walkermetalsmith.com>
        Publisher, free eNewsletter, "Repairing Metalware:"
        <http://walkermetalsmith.com/repairing_metalware.htm>

        [Non-text portions of this message have been removed]
      • Andrew Werby
        Message: 25 Date: Mon, 2 Aug 2004 17:50:51 -0700 From: Brewer Subject: RE: Plaster Moulds for Brass Take a look at this site. She uses
        Message 3 of 7 , Aug 3, 2004
        • 0 Attachment
          Message: 25
          Date: Mon, 2 Aug 2004 17:50:51 -0700
          From: "Brewer" <brewer@...>
          Subject: RE: Plaster Moulds for Brass

          Take a look at this site. She uses plaster to invest the wax in . Remember
          that you need to fire the plaster and have it at temp before you poor. Any
          moisture in the mold will cause an explosion.
          http://www.stonefire.biz/index.php?page=gallery&gid=13
          Dan in Auburn

          [That site is long on pictures but short on text. The investment material
          used for bronze (or brass) casting contains plaster (gypsum) but isn't just
          plaster. That's like the difference between cement and concrete - the gypsum
          is just the binder; it's the aggregate that makes it work. There are plaster
          molds made for ceramic slipcasting that are straight plaster; they won't
          work for brass. As Dan points out above, all plaster-based molds have to be
          burned out thoroughly before pouring metal into them. This requires
          temperatures of about 1000F - baking in a home oven isn't sufficient, as
          chemically-bound water has to be eliminated as well as free water and all
          traces of wax.]

          Andrew Werby
          www.unitedartworks.com

          -----Original Message-----
          From: uscg_e7 [mailto:uscg_e7@...]
          Sent: Monday, August 02, 2004 9:30 AM
          To: hobbicast@yahoogroups.com
          Subject: [hobbicast] Plaster Moulds for Brass

          Can I use a plaster mould for casting brass?
        • Brewer
          Yes but, I suggest that you find an Art foundry near you that does brass in the lost wax method. They use a ceramic investment system that is sprayed or
          Message 4 of 7 , Aug 3, 2004
          • 0 Attachment
            Yes but, I suggest that you find an Art foundry near you that does brass in
            the lost wax method. They use a ceramic investment system that is sprayed
            or dipped on to the wax positive. The wax is then burned out and the shell
            is fired. When they get enough of the shells to warrant a pour they fire
            the shells again to bring them up to temp The shells are held at temp until
            just before the pour. They are then hung on an iron tree. Then the brass
            is poured into the shells.

            Here is a repost of an earlier message
            I don't use slurry. I don't have the equipment. So I do the next best
            thing.
            First I use plaster and silica flint mixed in equal parts by volume,
            and
            brush a coating on the whole thing to 1/4 inch. We also use a few drops
            of
            Jet Dry, the dishwasher stuff, to the mixture which makes it adhere to
            the
            wax better. This gives the metal a smoother finish without grinding. It
            takes to polishing better. Less grinding means more of the details from
            the
            original wax show in the finished bronze.
            Then I use plaster, sand and what we call "luto" which is old
            investment
            ground back to a powder. It is mixed in equal parts by volume and
            hand
            packed to at least 3/4 of an inch around the wax. Then chicken wire is
            wrapped around the sides and bottom with a final coat of investment to
            hold
            the wire in place. Generally I fill it in and flatten the bottom,
            mainly so
            it is more stable when casting. The luto helps with the expansion
            during
            burnout and casting to prevent major cracking and the chicken wire
            keeps the
            whole thing from coming apart during pouring. I have done some
            experimenting
            with other things to replace the luto. Wet sawdust works. It burns out
            with
            the wax and the investment gets very light weight. It looks a little
            scary,
            being so light weight, but works fine. This method can lead to some
            flashing
            at times especially if care is not taken to make sure than there are no
            air
            pockets while packing it. But very few of my pieces have ended up at
            the
            welder's for repair(less than 10%). Cups and sprews need to be large
            with
            the sprews tapered down to the piece, as metal shrinkage can be a
            problem,
            and the piece needs to be well vented. I did a narrative with pictures
            on my
            web page if you want to go look:
            http://www.stonefire.biz/index.php?page=gallery&gid=13
            The investment process is about half way down the page.
            Burnout is done in an electric kiln adapted for the process, 24 hours
            at
            1100 degrees. It is slightly more complicated than that but if you want
            that
            process too let me know. Then we place the warm investments (about
            300
            degrees) in a tub filled with pumice and sand in case of metal leakage.
            When
            working with students who have never done this before, we occasionally
            have
            a blowout. I have never had one, but I have seen a few and it was
            easier to
            recover the metal from the sand than from the floor.
            If you have any more questions let me know. I am happy to help.
            Amy

            Good luck in your quest Dan in Auburn

            -----Original Message-----
            From: Peter Sibley [mailto:sibleyp@...]
            Sent: Monday, August 02, 2004 7:17 PM
            To: hobbicast@yahoogroups.com
            Subject: Re: [hobbicast] Plaster Moulds for Brass

            Do you think that system could be modified to use a thinner plaster coat ,
            say 10 or 12 mm ( 3/8" or 1/2") then backed up by vibrated sand? It would
            speed the whole process up .
            Peter Sibley

            ----- Original Message -----
            From: "Brewer" <brewer@...>
            To: <hobbicast@yahoogroups.com>
            Sent: Tuesday, August 03, 2004 10:50 AM
            Subject: RE: [hobbicast] Plaster Moulds for Brass


            > Take a look at this site. She uses plaster to invest the wax in .
            Remember
            > that you need to fire the plaster and have it at temp before you poor.
            Any
            > moisture in the mold will cause an explosion.
            > http://www.stonefire.biz/index.php?page=gallery&gid=13
            > Dan in Auburn
            > -----Original Message-----
            > From: uscg_e7 [mailto:uscg_e7@...]
            > Sent: Monday, August 02, 2004 9:30 AM
            > To: hobbicast@yahoogroups.com
            > Subject: [hobbicast] Plaster Moulds for Brass
            >
            > Can I use a plaster mould for casting brass?
            >
            >
            >
            >
            > This list is for discussion of metal casting
            > and does not accept attachments. For off topic discussion and to share
            > photos and stuff: join Sandcrabs by sending a blank message to:
            > sandcrabs-subscribe@yahoogroups.com
            > http://groups.yahoo.com/group/sandcrabs
            > Please visit our sponsor: Budget Casting Supply
            > http://budgetcastingsupply.com/
            >
            > Files area and list services are at:
            > http://groups.yahoo.com/group/hobbicast For problems that cannot be
            > otherwise solved contact the list owner by email:
            > owly@...
            >
            >
            > Yahoo! Groups Links
            >
            >
            >
            >
            >
            >
            >
            > This list is for discussion of metal casting
            > and does not accept attachments. For off topic discussion and to share
            photos and stuff: join Sandcrabs by sending a blank message to:
            sandcrabs-subscribe@yahoogroups.com
            > http://groups.yahoo.com/group/sandcrabs
            > Please visit our sponsor: Budget Casting Supply
            > http://budgetcastingsupply.com/
            >
            > Files area and list services are at:
            > http://groups.yahoo.com/group/hobbicast For problems that cannot be
            otherwise solved contact the list owner by email:
            > owly@...
            >
            >
            > Yahoo! Groups Links
            >
            >
            >
            >
            >
            >




            This list is for discussion of metal casting
            and does not accept attachments. For off topic discussion and to share
            photos and stuff: join Sandcrabs by sending a blank message to:
            sandcrabs-subscribe@yahoogroups.com
            http://groups.yahoo.com/group/sandcrabs
            Please visit our sponsor: Budget Casting Supply
            http://budgetcastingsupply.com/

            Files area and list services are at:
            http://groups.yahoo.com/group/hobbicast For problems that cannot be
            otherwise solved contact the list owner by email:
            owly@...


            Yahoo! Groups Links
          Your message has been successfully submitted and would be delivered to recipients shortly.