Hi there. I am wondering about casting, things a wee bit larger than
jewelry casting. A foot or so. I have the traditional lost wax
casting before me, it’s an assignment, yet I’m left wondering…
Is there anything that I can potentially easily sculpt/model out of
for the larger masses and then perhaps dip that in wax and add extra
wax detail on top? I could then expose it to water or something
which gets rid of the origional non-wax material leaving my nice
hollow detailed wax model… or something to entirely replace the
wax itself that can be burned out… paper clay or sugar substance or
some other odd thing… hell, maybe the thing is already
commerically available and I’m just unaware. Any ideas? Outright
rejections? Similar thoughts?
I’ll probably just do it the normal way… but I can dream, can’t
I? ;}
You can get water soluble wax (which I believe is wax plus an equal
amount of bicarbonate of soda, someone tell me if I am wrong). Model
this and then coat or paint on carving wax.
Sometimes it is worth just experimenting, sugar lumps, flour and
water paste, paper clay, meringue, biscuits, anything that water will
dissolve! This is how discoveries are made, and it’s all very cheap
to try!
You can use Styrofoam. The best way to work it is to make a large
"U" shape out of coat hanger wire and string a fine stainless steel
wire across the ends of the U. Then get a large dry cell battery like
one of those squarish ones used for camp lanterns and connect the
positive and negative battery leads to the ends of the wire strung
across your U frame. This wire will heat up and cut or melt it’s way
through the Styrofoam easily. You can also use saws, rasps and
knives, etc. Now as to the Styrofoam, the best kind is that pink
stuff you get at building supply stores that is used for insulation.
It’s dense and has a fine grain. When it’s time to dissolve it out of
it’s wax coating, pour acetone or even gasoline into the form and
the Styrofoam will instantly dissolve.
A water soluble wax is available. Use it as the core of your carving
and build onto it with hot wax.
After you have finished your carving simply place the item in warm
water and the core will melt. Of coarse you need to have an opening
for the soluble wax to flow from so the model can not be completely
enclosed.
You could also do the traditional method used by sculpture artists
and make a core of Investment ( plaster ) and build your wax on this.
You would need to embed wire rods that will anchor the core to the
outer Investment so that it does not move during the burnout. The
drawback to this method is that the Investment core remains inside
the casting.
I believe Marty Hykin has posted some additions to my suggestion
regarding safety, and the fine points of construction the U shaped
styrofoam melting saw. Take note anyway;
When exposed to any kinds of chemical fumes, it’s best to have a
fume extraction system, but even so, I think it wise to get a good
fume mask with a pair of filters specifically made for the kind of
fumes you might be exposed to. You can research this, and what’s
more, there’s a good book I can’t remember the name of that is all
about the safety hazzards artists and craftspeople are exposed to.
Maybe somebody here know of it.
Next point, the fine stainless or nichrome wire used to make the
foam saw, which serves as it’s blade, must be insulated from the rest
of the metal frame. This requires wrapping the ends of it in some
material that is both non-conductive and heat proof. I use
fiber-frax, which is an insulation material (refractory, actually)
used by glass blowers, blacksmiths, etc. If you go to an electrical
supply area in your local hardware store, you can find something to
substitute. This takes a little creativity.
you can use the soap kits from the local big box crafts stores and
some even have the water soluble wax. than like the others said build
up your item. They also have a low temp mold making material that
will melt out in warm water and is reusable.It is called Flexwax 120
by AMACO it is a plastic wax.
It melts at 120’F to a clear honey like liquid. it was in the wax
section of the big box craft store and comes in a 2 1/2 pound block.
Distributors tout a water-soluble wax for the buildup of hollow
forms. I don’t have direct experience with it. Too often,
distributors just care about pushing goods out the door. Quality,
detailed explanations and instructions get short shrift. Or you have
to scramble around to other suppliers for a necessary complement
good.
Paper clay may be worth exploring, sugar is an overpriced commodity
in the U.S. in the name of protecting a lagging industry.
The usual way this is done these days is by making the model solid,
in clay, wax or whatever material works best, then making a rubber
mold from it and casting wax into the mold. The wax is poured in then
poured out, leaving a hollow skin that casts well, using the normal
lost-wax process. This has the advantage of allowing multiple
castings to be made, or having the opportunity of producing another
one if the first casting doesn’t come out well. To cast hollow
pieces, foundries sometimes use a more porous mixture to fill
interior volumes (cores) and also provide core vents to the outside
of the mold, since, being heated on all sides, cores tend to outgas
more than the rest of the investment. Metal core pins are also pushed
through the wax shell, to keep the core from breaking loose and
shifting its position.
Historically, people have done one-offs by building a core first,
out of a porous investment material, adding wax and detailing it, and
then encasing the whole thing in more investment, burning out, and
casting. I suppose you could build a core in sugar or something else
that’s equally soluble, as long as it was possible to introduce
investment into the space it leaves behind. Jewelers sometimes use
water-soluble wax in this manner, but that would probably be
expensive for a foot-high sculpture.
I want to add some detail to one of the suggestions you received to
your query about dissolvable modelling material.
David Huffman’s idea (styrofoam) is very good for the size objects
you are intending to work with - but incomplete - some vital safety
details are missing.
Here’s a copy of what I sent to him.
Here's a small correction or addition re styrofoam cutting
with a hot wire ; It works great - but...
First - The fumes from hot or burning styrofoam are very very
bad fumes indeed - dangerous to mind and body. I don't know
Angela, the person who asked about it - maybe she is
sophisticated and knows enough to have positive fume-extraction
set-up available in her workspace - but if not she, and others,
should know about this.
Second detail - Of which I am less certain - It seems to me
that the electric current would travel through the large
cross-sectional area of the coat hanger wire easily and
therefore not press through the resistant, thin stainless
cutting wire with enough oomph to heat it hot enough. You can
tell by my highly technical language that electric things are
not my forte - But I think if the arms of the "U" shaped frame
were insulated or separated from each other rather than made of
one continuous piece, the current would have only the stainless
wire through which to travel and then your scheme would work
quite well.
And finally - Acetone, gasoline and the like - not good indoor
toys either. Explosive vapours, toxic fumes - the usual
drawbacks. (And might even dissolve the wax surface along with
the styrofoam core.)
I mean - I know all of the above can be done - I knew a guy
who built whole airplanes with the technique. Covered the
styrofoam shapes with fibreglass & resin, then after the resin
set hard he dissolved out the foam and had a lightweight,
hollow wing, or tail or whatever - But when you're putting the
ideas out for folks in general, it's good to know for sure that
they've got the experience required so they don't fry their
brains or blow up the neighbourhood. Give 'em all the
they need.
The airplane builder, by the way, crashed his last plane on
its maiden flight and shuffled off this mortal coil - maybe too
many styrofoam fumes?
Angela - just as a coincidence, but your email name “quercus” caught
my eye - Latin for Oak - I had intended, long ago, to name one of my
childen “Quercus” because I loved oak so much but I got talked out
of it and they all ended up with other names. Probably just as well
or school buddies would have ended up calling him “queer cuss” or
something.
How, why, did you choose that name for your email address?
I just remembered something that might be helpful here. Have you
ever put a bar of Ivory soap in the microwave? It’s cool! It puffs up
into a huge, flaky mass. If I remember, you can pack it like snow.
Maybe this would work for a non-toxic modeling material that would
dissolve out with water.
This wire will heat up and cut or melt it's way through the
Styrofoam easily. You can also use saws, rasps and knives, etc. Now
as to the Styrofoam, the best kind is that pink stuff you get at
building supply stores that is used for insulation.
Hot wire cutting of Styrofoam works really well. We used to cut
slabs of the blue,insulating, close grain Styrofoam in the factory
where I work, but please be sure you have some excellent ventilation.
The fumes that come off can be a serious respiratory hazard. We
eventually went to a different material because of the safety
concern. In our MSDS for Styrofoam we found that there was a
possibility of cyanide fumes being emitted when it was heated.
I use pieces of Styrofoam for forms, containers and bead holders in
my workshop, but if I have to cut it, even with a knife, I do it
outside. Also, you would still have to find a way of disposing of
the melted Styrofoam safely.
I wonder if the wax wouldn’t be the better way to go. Can you
reclaim it once it’s melted and use it again? An added bonus for
using wax. I haven’t done any casting so am not sure of the
properties of the wax once it’s been used.
Have you ever put a bar of Ivory soap in the microwave? It's cool!
It puffs up into a huge, flaky mass.
You are an original thinker!
Putting a bar of Ivory soap in a microwave? Who would ever have
thought of that in the first place? And why? Only reason I can think
of is for the sheer hell of it -which is what i mean by an original
thinker. Sheer genius. What were you thinking?
We banished our microwave to the dump after we discovered that it
destroys 90% of whatever little bit of good remains in the
industrial- grade vegetables we get these days. But if I still had a
microwave on the payroll, I know what I’d do tonight. I’d invest in a
bar of Ivory soap and settle in. For sheer entertainment it’d
probably beat anything showing on that other box with the glass
window on the front.
What else have you microwaved lately?
Best thing I ever did with our microwave while we still had it - I
picked a bouquet of fresh catnip from the garden and tossed it into
the infernal device to dry it out. Within 3 minutes all of our cats
(we had at least 7 of the little pissers at the time) had gravitated
to the kitchen and instantly became well and truly stoned on the
fumes. The funniest part was that they couldn’t locate the source of
their craziness - all they knew was that they were intensely,
ecstatically, insane.
Makes me wonder about some other kinds of weeds. Maybe we shoulda
kept the microwave.
Marty Hykin - In Victoria BC, apparently suffering vestigial traces
of cabin fever due to our mild winter weather.
And another thing -
Not that I’m really worried about this - but I wouldn’t count on
micro-waved Ivory soap fumes being non-toxic.
Oh well, Ivory soap was good enough for Linda Lovelace (for those
old enough to remember)
Is there anything that I can potentially easily sculpt/model out of
for the larger masses and then perhaps dip that in wax and add
extra wax detail on top? I could then expose it to water or
something which gets rid of the origional non-wax material leaving
my nice hollow detailed wax model....
Might give this a try, I am not recommending, just ran across it in
another search, they have a lot of material here for casting large
objects.
We banished our microwave to the dump after we discovered that it
destroys 90% of whatever little bit of good remains in the
industrial- grade vegetables we get these days.
What evidence and/or research studies do you have that support your
statement?
You wondered: “Putting a bar of Ivory soap in a microwave? Who would
ever have thought of that in the first place? And why?”
OK, here’s why. Those of us who hate to discard anything remotely
useful, like slivers of bar soap, think of it.
Instructions: Put the new bar of soap in the microwave. Add a few
drops of water to the top of the bar and place the sliver of soap on
the water drops. Microwave on high for 10 - 15 seconds. The soap
sliver becomes pliable, the new bar softens and the two bars can be
mashed together. Let it cool. Use as usual. No more soap slivers.
However, it seems obvious that Ivory soap does not lend itself well
to this technique!
We used to cut slabs of the blue,insulating, close grain Styrofoam
in the factory where I work, but please be sure you have some
excellent ventilation. The fumes that come off can be a serious
respiratory hazard.
The original post about styrofoam reminded me of this, but I’ll post
it now. Once I heated some plastic for some repair or something.
Frankly I don’t remember what it was. As it burned and fumed, though,
I got a whiff of it, and immediately knew it was poison. I mean, like
really, like another good sniff and I could be dead. Just a feeling
you get that what you’re doing is not a good thing to be doing. Many
plastics - styrofoam, acrylic, styrene, mostly just stink and aren’t
good for you, but I’d be careful about heating just any old plastic.
This was more like Bhopal.
