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Wax injection to RTV molds

I am new to casting and wonder if anyone can help me out.

I have casted some designs and want to duplicate them. I have access
to a classroom for casting.

I will be making RTV molds since I won’t need many duplicates and it
doesn’t require much. Can anyone tell me if I need any equipment to
do injection wax or if there’s other ways to do the wax in RTV molds?
I couldn’t find info on that.

Thanks in advance!


For small amounts of work you can get I think they are still
available from jewelry suppliers) a hand pump wax injector. For a lot
of work, an air pressurizer wax injector is great. One of these new
is probably $300-400 (check out jewelry equipments suppliers), and
you will need a small air compressor ($100-200). You will also need
wax and here you have choices of 100’s. Sooooo many different
attributes to the different waxes and actually this is the thing
that will present the most difficulty for you as to what you require,
like, how you work, etc. Hope this help a bit.

John Dach

Hi Anne

I spent a long time with this as I didn’t have a vulvaniser nor a
wax injection machine. It is possible to do small run manual wax
injections with patience and very little equipment. Here’s what
you’ll need…

A depilatory wax heater available from beauty supplies for around

Two sheets of plywood held together with 4 thumb screws and a hole
drilled in the middle on one side ( to meet up with the opening in
your RTV mould). This looks like a flower press and is necessary to
apply enough pressure to force the wax into very small crevices.
Otherwise you end up with air bubbles and partial moulds.

A syringe, just the ordinary type you can buy from any chemist.

You put the RTV mould into your press, apply appropriate pressure.
Suck some molten wax into your synringe and inject it by hand into
your mould.

I had success casting wax bezel cups with this setup although it
does take practice and patience to get the process just right. It
took me about a week of constant casting to get everything just
right and it still produces a dud casting around 25% of the time.
But for a very low budget setup I think that’s acceptable.

There is also a limitation about what kind of mould you can make. It
must be two part, and it can’t exceed the size of your press.
Because the wax is not injecting at the same high speeds it would
from an injector machine the pieces also need to be fairly small as
the wax does cool very quickly. My bezel cups were about 2cm x 1cm
x.5cm. Also be careful because hot wax can spew out of the mould
onto your hands if you inject too much too fast.

I had very little success with commercial injection waxes. They
tended to be too brittle and too fast cooling to work. I used a
carving wax from a sculpture supplies place and had good success
because the wax was slow cooling and quite flexible when set.


If the molds are flat, use injection wax and a wax pen on low to
melt a layer of wax in the mold and remove all the bubbles. If the
wax pen is too hot, you’ll effectively boil the wax as well as burn
it and it will leave bubbles on the surface of the mold.


I jsut bought a hand pump wax injector they are 189 dollars fro Rio
Grande or stuller they had the cheapest prices on a little1 pinter I
been making waxes like a happy fool lol

ps first thought after making 50 waxes was ohh I didn’t buy enough
wax flakes lol

I am so hooked on this casting lol

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