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Lost wax tools and techniques


#1

Hi all,

I have been researching whether it is sound to mix waxes for casting
a piece using the lost wax method. For example to combine, in the
same piece, green wax wire and pink sheet wax in the making of a
flower. I would want to do this because I find the different types
of wax lend themselves to different types of structures, forms, etc.
The sheets lend themselves to petals, and the wax wire to stems or
other linear elements. The workflow of building a model all at once
really appeals to me.

People seem to say that this would cause problems during the casting
process due to waxes having different melting points. On the other
hand I have seen examples through online wanderings, of people who
do use waxes in this way. One thought I had was to coat the entire
piece, once finished with a thin layer of wax of one kind, though I
wouldn’t know which to use and whether this would solve the problem.
I have been told that wax combination models can be directly molded
rather than cast, but this would be inefficient for me given the
amount of work I do on a metal casting before I have a mold made. If
I go directly from wax to mold it will have to be molded again after
finishing.

The only other solution I could think of would be to cast components
separately then assemble, or give to a contractor to assemble.

Any thoughts, advice, articles, or feedback would be appreciated.
Otherwise it will be trial and error which is costly and time
consuming.

Mary


#2

Mary,

The only thing I can think of is the wax for the sprue and/or sprue
extensions should be of a wax that will melt out first so there is
no blockage for the other waxes to flow out of the investment. I use
the red sprue with yellow sprue extensions. My wax models are green
wax or turquoise injection wax and all is good.

Good Luck.
Ken Moore


#3

Mary,

Some thoughts:

The sheets lend themselves to petals, and the wax wire to stems or
other linear elements. The workflow of building a model all at
once really appeals to me. People seem to say that this would cause
problems during the casting process due to waxes having different
melting points. 

I disagree. The waxes do have different melting points but, , so
what? There may be a need to “look” at things and make sure low
melting wax in not “captures” between high melting wax within the
investment, so that the molten material cannot flow out/escape (the
hotter wax gets the more it expand so one needs to at least allow
for a pressure release, if needed).

On the other hand I have seen examples through online wanderings,
of people who do use waxes in this way. One thought I had was to
coat the entire piece, once finished with a thin layer of wax of
one kind, though I wouldn't know which to use and whether this
would solve the problem. 

Any detail will be jeopardized with this.

I have been told that wax combination models can be directly
molded rather than cast, but this would be inefficient for me given
the amount of work I do on a metal casting before I have a mold
made. 

Why are you having to do so much metal work? The best place to do
work is in the wax, shock should be near perfect when cast and the
casting should be near perfect too. RTV mold rubbers are GREAT for
making molds of waxes, often leaving the wax in perfect or near
f=perfect shape after molding, depending on what the master looks
like/construction/complexity.

If I go directly from wax to mold it will have to be molded again
after finishing. See the above comment. The only other solution I
could think of would be to cast components separately then
assemble, or give to a contractor to assemble. 

You are starting to loose control of YOUR work with this direction.

Any thoughts, advice, articles, or feedback would be appreciated. 
Otherwise it will be trial and error which is costly and time
consuming. 

Hope this is a bit of help. If further questions, let fly. I am
happy to do what I can to lend assistance or give alternative ideas.

John
john dach


#4
People seem to say that this would cause problems during the
casting process due to waxes having different melting points. 

They are wrong. You can mix wax types to your hearts content.
Different melting points is often precisely the reason one would mix
waxes, not a deterrent to it, such as using lower melting waxes to
join parts in higher melting types. The very much higher melting
types, like carving waxes, can take longer to burn out, and don’t
work with steam dewaxing, but this doesn’t interfere with the actual
casting, only with how you burn out the flask. And its the same,
whether or not those carving waxes were mixed with the lower melting
types. As a general rule, you want sprue waxes to be, if possible,
lower melting types or the same as the models, so that during
burnout, the melted wax can most easily flow out of the flask instead
of soaking into the investment. But that’s almost automatic, since
all the sprue wax types sold are that sort of lower melting type,
and even if you didn’t do that, it would cast fine. You just might
need a slightly longer burnout. So the bottom line is your choice of
which wax to use should be driven by what is best for making the
model and how you wish to work with the wax. After that, the casting
process is pretty much the same, so long as burnouts are long enough
to fully eliminate the wax and residues.


#5

I often mix waxes in pieces. As you say, some waxes are better for
certain elements than others. I think the temperatures in burnout
are so high that the variations in wax melting temperatures don’t
make any difference. As my artist husband says, art is achieved by
any means necessary.

Janet Kofoed


#6

I have used many types of waxes together for casting. As long as the
jointsbetween the waxes are good then it should make little
difference if good investment techniques are followed. Basically
anything that will burn out or melt out without any or much
expansion or left over residue will work just fine. Even butterfly
wings coated on the underside with wax for thickness will cast
beautifully. Play have fun and take lots of notes as to what works
and what does not.

Vernon Wilson
Panama Bay Jewelers


#7

Hai,

We are using Riace wax injector with using Freeman Flakes Premium
Injection wax-Turquoise-50051.

We were facing the following defects while injecting wax.

  1. Cooling
  2. Air-bubbles
  3. Improper filling

We are not using the talcum powder while injection the wax.

We are using the talcum powder in the air-vent places in the mold.

Could you suggest, How to avoid the above problem in waxing stage?

Any Techniques is available…

Regards,
KAC


#8

I create all sorts of designs using everything from Ferris carving
wax, spruce wax sheet wax, purple build up wax, injection waxes and
any wax that I find.

I crashed and banged designs without ever considering how the waxes
would burn out.

I burn out the flasks in a fully loaded oven for around eight hours.

I have never had any failure that could be attributed to how the
waxes went together.

I have had a failure or two that was caused by quenching too soon.

The best advice is to not worry about construction sequence. Make
sure alljoints are free of voids. Just create, take notes and have
fun.

If you vacuum cast sterling silver check out my paper on no fire
scale casting on the tips from the jewelers bench.

Lee Epperson


#9

Thanks to all who have generously shared their knowledge and
experience withme! I’m also happy that i was wrong about not being
able to mix waxes. One caveat that I want To add Is that I have no
control over burn out or anythingelse that happens once I’m done with
the model, as I outsource casting to Taba in NYC. I Have always been
satisfied with the quality of their work though, so I don’t see this
as an issue.