Molds for casting natural materials

Hello, I would like to cast natural materials. I tried casting some
starfish and seahorses, some turned out and some only partially were
cast. Someone recommended that I make a mold first. Can anyone tell
me what the easiest type of mold, with the least amount of equipment,
would be to make and how do I go about this? OR, if anyone can give
me tips on how to invest and burnout natural materials with better
results than I have gotten so far. I would also like to try twigs,
as well as the sea creatures. Thank You, Christine

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Hi Christine! I tried, a lot of years ago to cast natural materials. I
succeeded in it, but only with very small pieces. The problem is that
natural materials do not burn perfectly, always leaving ashes in their
mold. Anyhow, you may try following these steps :

  1. Dry up , very very well, the piece before casting(better if it
    do naturally - or into an oven at lower temperature 50 C�)

  2. Put into the flask setting a lot of little wax sprues in each
    important and thin part of it.

  3. Put the investment into the flask ( I use KERR SATINCAST 20) adding
    water in ratio 42/100

  4. Set a very long burnout cycle, 8 hours at least, in the
    furnace.Bigger is the object,longer the burnout till a
    maximum of 12 hours too.(EX: 1 inch scorpion about 9 hours)

  5. Reach the right temperature of the flask for casting (about
    400 C� for casting gold) and finally…

  6. CAST !!! Better if you do into a vacuum system.

This way allowed me not to have problems with ashes defaults.

In alternative you may have a mold,( to fill with wax injector
,obviously), using the silicon double-print technique as the dentists
do. I hope these will be useful. TRY and have a GOOD DAY

Dear Christine,

This is Michael Knight at CASTALDO rubber.

We have two new products that are perfect for making molds of natural
materials – leaves, twigs, acorns, sea shells, flowers, insects, wax
models, gravestone inscriptions, statuary – I’ve even made a mold of
a strawberry and another of a chocolate bon-bon.

One is our CASTALDO LiquaCast liquid rubber, which is ideal for
delicate objects.

The other is our CASTALDO Quick-Sil, which is a two- part putty that
you mix by hand like clay and press into and around a natural object.
It cures in only 15 minutes without any equipment more complicated
than a C-clamp – at trade shows I just use my thumb.

I’d be happy to send you a small free sample of each, with
instructions of course. If you’d like to try it, please give me your
shipping address – no PO boxes, please.

Anyone else out there want to try it??

You can read more about these products at:


F.E. Knight, Inc.
120 Constitution Blvd.
Franklin, MA 02038
United States of America
Voice: 508-520-1666
Fax: 508-520-2402

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Hi cristina First I thought you were offering a natural way for
casting Because this thing interest me a lot , Its wonderful to do or
work with any thing without spouling nature Your question is not a
dificult thing to do I read in a book which teachs how to cast any
thing and they have shown unpleasent thing to cast and I hatted doing
that but they did , they casted a cocroch they symply put him in the
solutiong without any mould and he evaporated from the heating
prosses then to casting But I wich from you not to spoil a natural
created thing to make it a metal the true secret in their beauty is
there naturale creation they were not made matals , yu can do a now
creation which is for matals hope this helps you and bye Mazen Daouk
from Lebanon

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Aloha Christine, For a quick, inexpensive mold of things that don’t
burn out well (like seahorses and starfish, due to their
composition), I would use a material called Algenate (available thru
a dental supply house or ask you dentist).The material is used for
making impressions of peoples teeth in the dental trade.A similar
material is sold in hobby shops called, MixaMold. Then you could drip
wax in the resultant mold or use a glass eye dropper ,alcohol lamp
(or bunsen burner) and dental inlay wax to inject a two part
mold.Their are some cold set silicons and RTV compounds that you
could use as well. Micheal Knight is on this list and may still be
making samples of his new molding materials available. You should be
able to find his email in the achives.

Best Regards,

Christian Grunewald
Precision Modelmaking Technologies
(808) 622-9005

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Hi Christine, I have had twigs cast and they came out beautiful (in
sterling silver) . They were cast at Ampex casting in NYC on 47th st.
Joe is the owner and a very nice guy, I am sure if you call and talk
to him he will be able to give you answers. He always seems to want
to help those in the trade. Diane

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Christine, You may wish to go straight to the molding process for your
sea creatures. Twigs, leaves,etc will burn out well in a longer
burn-out cycle. If the leaves are especially thin, try painting the
backs of them with wax to add thickness. Your starfish and seahorses
resist a complete burnout because they are made of calcium carbonate,
which does not like to burn. I have had some sucess with molding
these types of objects. A very cheap method is to make a two part
mold using common bathtub caulking silicone. There are two types, you
want the type that cures with acetic acid (smells like vinegar). The
procedure is as follows. Take the object and get it wet. Smear or
brush on a coating of diluted liquid dish soap. This will act as your
mold release. Next, using a caulking gun, squirt out a glob of
silicone into the palm of your well soaped/watered hand. If your hand
is dry you’ll have a sticky mess. Flatten the glob out into a disc/
losenge shape, and put it on a soaped surface such as a jar lid or
other flat submersible object. Make another disc shaped glob of
silicone. Now, place your object to be molded on top of the first
glob, and press (lightly) the second glob on top of it. You should
now have what appears to be a little silicone sandwich on the jar lid.
Submerge this entire piece in water. Water will accelerate the
curing. To really accelerate the curing time, gently whip water into
the silicone before making the sandwich. This can be tricky though,
as it is hard to prevent air bubbles from being captured in the
silicone during the mixing. After allowing many hours to cure, remove
the mold from the water, and gently poke it with your finger. It
should feel firm. If it feels like it is just a thin skin with
pudding underneath, leave it to dry longer. Once you feel sure it is
dry, you can then cut the mold open along its edge, and separate the
two halves. The scalpel may damage the object inside, especially
since the moisture may have softened it, so be ready to sacrifice a
starfish or two. This type of mold can then have both sides filled
with wax, and then be slapped together before the wax sets. If you
are only concerned with the top or front side of the object, the
sandwich method is not necessary. Just press the object face down
into the silicone and forget about the top half. If you want to use a
wax injector, your best bet is probably an RTV silicone mold. These
molding compounds are somewhat costly, but produce remarkable detail.
There are mold frames and clamps available specifically for these
types of molds. Check out your Swest, Rio Grande, or similar catalog
for details. Both of these methods are ideal for the type of projects
you are describing, since there is not the extreme pressure or heat
involved with the conventional rubber mold vulcanizing process. Good
luck, I hope this info helps!

Michael Holland

Christine, Years ago I invested various sea forms when I was kiln
casting glass. There are many sea life forms which will not burn out
because of their compostion. Most land-based organisms such as leaves
and twigs, are carbon based forms, and carbon will burn out. However,
some sea animals like starfish, sea urchins, crabs with shells, have
"skeletal" structures which contain calcium. This doesn’t burn out.
Also many seaweeds and corals have a silica based structure, and
silica won’t burn out either. Shells (such as snails, clams, etc.) are
calcium carbonate; this will just turn black. On the other hand, some
fish (such as seahorses?) may work if there is no boney skeleton to
contribute calcium. If you want to avoid all the trial and error to
discover which will and won’t work, I’d recommend a rubber mold
process for these kinds of forms.

Hope this helps.
Rene Roberts

Christine, I have had success casting orchid flowers, dogwood flowers,
leaves, twigs etc as well. I do direct burnout at 1300 to 1500 deg F
for about 6 to 7 hours and then cast at about 900 deg F. I find that
spraying the flowers with a very fine spray of lacquer thickens and
strengthens them sufficiently to do the spruing but you must be
careful. I have also done crab claws by making a mold using Castaldo
"LiquaCast" two part RTV in a standard mold frame with aluminum plates
as covers. I make a solid wax model and then drill out the center of
the wax. Keep experimenting…succcess will be spectacular! Don at
The Charles Belle Studio where simple elegance IS fine jewelry.

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