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Water soluable wax - (WSW)


#1

How did you guys know that I was just thinking about water soluble
wax! I can’t seem to conceptualize exactly how it would work to
cast (or have someone cast for me) a hollow piece. Let me run
through the process as I imagine it:

Scenario 1:

  1. Build the wax piece around the WSW so it is completely surrounded
    by the regular wax.

  2. Leave a hole somewhere, and the put the piece in water until the
    inside wax dissolves and runs out. We now have a hollow piece.

  3. Send it to caster and poof–it all caves in when the pressure of
    the hot metal hits the hollow wax .,

Scenario 2:

  1. Follow 1 as above.

  2. Do not melt out the WSW wax

  3. Send it to casting person–then what happens?

I know I am missing something. Can someone take me through the
steps?

Many Thanks
Sandra Elegentinsects@aol.com


#2
    ... I can't seem to conceptualize exactly how it would work to
cast (or have someone cast for me) a hollow piece. 

You might want to check out the following:

https://orchid.ganoksin.com/t/soluable-wax-bead-making

I had to read it a few times over to let it sink in because the
process does not seem intuitive for some reason.

In the end though the fog clears and one can see what is happening:
investment replaces the WSW and that’s what allows the hollow shape
to be formed when cast.

Cheers,
Trevor F.


#3

Hi Sandra, I think I wrote to you before when you had questions about
casting hollow bug bodies. The following can be applied to that
issue.

SCENARIO 1:

  1. Build the wax piece around the WSW so it is completely surrounded
    by the regular wax.

  2. Carve, texture, etc. your surface while it is supported by your
    WSW core. Be sure to include pierced decorative holes in your design
    because you need enough holes to permit plaster to flow into the void
    that will be left after you dissolve the WSW core. Cut through the
    regular wax making certain that you expose the WSW core. When you’ve
    done all your surface treatment and piercing, dissolve the WSW.
    Clean up the holes in the regular wax bead (now hollow) with a
    scalpel because it’s easier to do it in wax than to file, grind or
    bur it out in metal. Occasional dipping of the wax in iced water will
    keep it firm while you work on it. If you did, however, make a very
    thin walled piece that is too difficult to handle without crushing,
    leave the cleaning to be done after casting. Make sure that you have
    enough openings to permit rapid filling of the hollow of the bead
    during the investing process. If plaster can’t quickly fill the
    void, you’ll end up with a semi solid piece.(Note: Your piercings
    need to be strong enough and placed such that they will anchor the
    plaster core in place so it won’t break away in the void during the
    casting process.)

  3. Consult with your professional caster about the most
    advantageous spruing of your hollow bead. If you had adequate
    piercing and enough conduits for wax flow in your design, you should
    end up with a hollow bead. You may have to do a bit of work to remove
    all the plaster - poke it out, steam it out, power spray it out,
    ultrasonic it out, all of the above.

SCENARIO 2:

If you do not remove the WSW and have it completely enveloped by
regular wax, you’ll end up with a solid casting. If you want a solid
casting, just work with a chunk of carving wax and be done with it.
Don’t use the WSW because it costs more and should be used where it’s
properties are an asset, not just a filler.

SCENARIO 3:

If you want to make a hollow wax bead or item without piercings, you
cut the piece apart. You would dissolve the WSW and cast the parts
separately and reassemble the parts back together in metal
(soldering, laser welding, cold connecting, etc.). You could also do
everything as in Scenario 1 but still cut the piece apart to have an
easier time removing the plaster after casting. Also, by cutting and
casting in two parts, you can clean the inside and you could mold the
two parts to reproduce your hollow item. NOTE: You should address
your seamline or connecting points in your design so you can blend,
camouflage, or accentuate them as needed. Some examples would be
smooth surface easily finished, a line designed to integrate the
natural soldering line, heavy texture like stippling to hide the
connection, a corner or knife edge to hide the solder seam, etc.

HTH,
Donna Shimazu


#4
   Build the wax piece around the WSW so it is completely
surrounded by the regular wax. 
   Leave a hole somewhere, and the put the piece in water until
the inside wax dissolves and runs out. We now have a hollow piece. 

Not quite. You have a hollow piece with a hole to the interior.
two or three would be better, unless it’s fairly large.

   3.  Send it to caster and poof--it all caves in when the
pressure of the hot metal hits the hollow wax

Hot metal never hits any wax, water soluble or not… The wax is
gone by then. In the investing process, because of the same hole
though which you dissolved the WSW, investment fills the hollow
center of the piece. The investment mold thus has a solid investment
core, connected by a bridge the size of that hole, to the investment
surrounding the wax. After the wax is burned out, the mold cavity is
also the thin hollow shape of the wax, surrounding that center core,
which needs to be held in position by that bridge. If the hole was
large enough, so the bridge securing the inside core to the rest of
the mold is strong enough to withstand the casting process, then your
casting is also a hollow metal shape, from which you’ll have to then
clean out the investment. This is why two or more holes are better,
since it better secures the center core, and makes cleaning easier
too. If you don’t want holes, other than the at least one through
which investment can fill the original wax during investing, you can
also poke metal pins through the wax model, so they extend from
outside the model to inside the model. If they are sufficiently
strong, and high enough in melting point to survive contact with the
molten metal in casting, then they can help hold the interior core in
place, since after burnout, they will extend from being imbedded at
one end in the core, through the mold cavity, to be imbedded at the
other end in the outer mold surface. After casting, they can be
just cut flush on the outside. If the wires are thick enough, they
usually can be the same metal being cast. And if the original hole
in the wax is too small, and you don’t use pins, then the center
investment core will break away from that bridge, and fall to the
bottom of the mold cavity, giving you a defective casting, since then
there will be a new, probably destructive, hole where the core now
touches the molds outer cavity. If it doesn’t touch, and the metal
completely covers, then the core is floating in an unpredictable
position inside the casting, and can’t be removed without drilling a
hole somewhere. When that’s done, probably it will be found that the
wall thickness of the hollow casting is way too thin somewhere, where
the core came nearest.

  1. Follow 1 as above.
  2. Do not melt out the WSW wax
  3. Send it to casting person–then what happens?

If the WSW is left in place when sent for casting, it then makes no
difference that it happens to be a different type of wax. you’ve
sent the caster a solid wax object, not a hollow one, so you’ll get
back a solid casting. All the wax, whether water soluble or not, is
removed during burnout. The WSW only becomes significant if you
dissolve it prior to investing the model. If you don’t then it
serves no purpose that’s any different from any regular wax…

   I know I am missing something. Can someone take me through the
steps? 

completely solid surfaced hollow castings can be done this way. You
need some sort of entrance into the model for investment to get in,
and for it then to be cleaned out. An alternative to this is to carve
the core of investment itself, using just pins extending through the
wax, to support it’s position. then you probably need less of a
hole, or can, if the pins are something like steel, pull them out of
the casting after, to get cleaning holes, filling them later.

Most commonly, water soluble wax is used to build cores for things
that are not completely enclosing a form, such as a filigree surface.
or wire frame sort of surface. Then the WSW is used just as a
support on which to build the rest of the model, and after dissolving
the WSW, you have a form with a hollow interior, but plenty of access
to that interior both for the WSW to be dissolved out, and investment
to then flow in.

did that help?
Peter Rowe


#5

There is a possibility that hollow waxes will trap air when the
investment is poured.

Vacuuming the investment will reduce the size of the trapped air but
may not remove all of it. When this happens the air pocket will
fill with metal making the section much thicker than you desire.
This problem usually occurs when the wax has only one opening and is
sprued at the open end. The investment will raise into the hollow
but will trap air in any pocket that is not vented.

Care should be taken to study the wax, where it will be sprued and
how the investment will enter the hollow to insure that no air will
be trapped. Vent holes should be drilled into the wax to allow air
to escape

It has been stated that it is important to provide a means of
holding the core of investment once the wax is burned out,
especially it the bridge (hole into the wax) is small. I cut a
piece of 12 gage sterling wire so that it is about 1/2 the length of
the core. I bend both ends so that they are perpendicular body of
the wire. I wax weld this piece to a 10 gage piece of wax wire.
The assembly is then wax welded to the wax model so that the
sterling wire extends into the hollow of the wax. The wire acts as
a re-bar and holds the core so that it cannot move. With this
method I do not have holes in the casting that need to be filled and
clean up is very easy. Lee Epperson


#6

Thanks to Donna Shimazu and Peter Rowe, I finally had the "aha"
experience about Water Soluble Wax. It is really great to have
those wonderful descriptions and thus a clear understanding of the
process. What a relief!! Sandra www.Elegantinsects.com