Casting a sea horse

Hello fellow orchidians!

I have a small sea horse that was given to me by my father-in-law,
who found it dried on the beach. It has the same texture and
hardness as would have a dried sea star. I would like to use it in
my jewelry but I don’t know the best way to do it. Cast it then mold
the metal piece? If so, will the sea horse disintegrate in the kiln?
If not, should I mold the sea horse directly into rubber? Will it
support the vulcanizer’s heat? Any feedback would be appreciated…
thank you all!

Benoit Hamel

Hello Benoit. We have done this before… Sea horses are very brittle
in general and will most likely be damaged in a vulcanized rubber
mold. I don;t think casting the sea horse directly will work as the
structure may not burn out correctly.

The best way to mold this would be to use a liquid RTV rubber that
cures on it’s own with no heat applied in about 16 hours. You have
to fashion a frame to poor the rubber into. What I have always used
is a small piece of PVC pipe… does not matter what color it is…
Make sure the pipe has enough clearance around the item… at least
1/2 inc or better all the way around the interior of the pipe . the
pipe should be at least 2 inches higher than the piece when the sprue
is added to the piece in . or more… Cut the pipe in half , length
wise, , then , tape the pipe back together with electrical tape.

The best way to mount the wax would be by connecting a strong sprue
to the sea horse, then take a flat piece of wood or plastic… weld
the wax to the wood or plastic… then use wax and weld the pipe to
the base… Now it’s ready to pour.

The RTV rubber usually works best if you vaccuum the rubber before
pouring it , then pour it slowly into the pipe… then , you may
need to vacuum the mold again to remove any air bubbles that are
trapped. Now, Let the RTV cure overnight.

Now, Remove the electrical tape from the outside of the pipe and
keep it as this will become your mold holder for the newly made
round mold. You now hand cut the rtv rubber .Your mold is now ready
for injection.

There are RTV rubbers that you can pour pewter directly into (
Petwer melts at about 450 oF ) and the pewter piece can be used for a
vulcanized mold. Contenti supply has this type of rtv with
instructions at 800-343-3364

This is not the only way to make frames for rtv rubber… but I have
always liked this method because the pipe becomes the mold holder
when you are done

Hope some of you find this useful as it can be used for
many different types of projects.

Daniel Grandi

We do casting,finishing in gold and silver, soldering, assembly
,engraving, cnc model work , enameling and all kinds of other
services for designers, stores and people in the trade.

Hi Benoit,

I don’t know if the sea horse will burn out in the kiln, but a safe
option for making a mold of it would be RTV (Room Temperature
Vulcanizing) silicon, which requires no heat, only time to catalyze.
I think most jewelry supply houses, such as Rio Grande and Gesswein
carry this material now, but you can also get it at art stores that
specialize in sculpture, such as Douglas and Sturgess in San
Francisco, CA. I have been using it for over 20 years to mold all
sorts of things, such as delicate waxes, and highly recommend it.

Best regards,


Make a siloconeof the seahorse then make a silver model from he mold

Benoit: I did the same thing that you are wanting to do 25 years ago.
Here is what I did. I pot a 1/8’ sprue on the curl part of the tail.
I put a 1/8" wax rod on the top of the head. THis was to take care
of any ash that was left after burnout. I dipped the Sea Horse that
was sprued onto the flask into a solution of de bubble solution. Let
set for 2 hrs. and then poured my investment. I burned out with a
12Hr sycle at 1200* F. and cast it in 14K. I cranked the casting
machine 4 times. I did two sea horses this way and they came out
great. They were made into Earrings for a friend who gave them to his
girlfriend. I hope this helps . Yours Bill S. Bates

Bill Bates, Owner
Royal Wildlife Miniatures
P.O. Box 3151
Torrance, CA 90510
Phone: 310-316-5944
FAX: 310-316-5944
Email: @Billy_S_Bates2

I have done this before with the very same item. I suggest you make
a Room Temperature Vulcanizing rubber mold (look it up in the
archives for more info about RTV rubber molds we have discussed it
several times) and cast the wax injections. This way you save the
original item for whatever use. Also whenever you burn out organic
items there is always a certain amout of ash and non-combustable
materials that tend to contaminate the castings. Wax injections give
much better castings and are easier to alter to accept stones etc.
Frank Goss