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 Making a mold can be very simple or it can be an art. It all depends
on the
intricacy of your part.
If you have never made a silicone mold before, begin by making a
mold of a simple part. The good
news is that silicone will not hurt your original.
AeroMarine silicone mold making rubber does not require use of a vacuum.
You will need mixing
containers, stirring sticks and probably a mold box into which to place your
pattern while making your mold. Depending on the size of the pattern,
1/2" of silicone moldmaking rubber is the minimum thickness necessary for
your mold. Making it too thick will reduce the flexibility of the mold-
too thin will reduce the resistance to tearing.
There are 3 basic types of molds:
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BLOCK mold, one
piece. The part usually has no negative draft and/or undercuts.
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The BLOCK mold, multiple
piece, can be made in the same way as the one piece mold. Just cut the
mold after it has cured to get the pattern out. Then use rubber
bands to keep the two halves of the mold together. Instead of cutting the
block mold apart, you can design it to be taken apart. One way is to
partly fill the container with the silicone mold making rubber, let it cure,
spread petroleum jelly as a release, then finish pouring the mold. When it
has cured, you can take the mold apart.
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The GLOVE mold, brushed onto the
pattern, requires the use of our thixotropic catalyst. This is so that
the silicone moldmaking rubber doesn't run off the surface of the pattern.
It also builds up much thicker than the regular catalyst. This type mold
is widely used in restoration of architectural designs on vintage
buildings. The silicone rubber is brushed onto the surface, allowed to
cure, then removed. Back in the shop, it is then supported and used as a
mold to cast additional parts.
Mold Release
Generally, silicone RTV mold
making rubber does not stick to anything, and nothing will stick to it. The exception is that it will stick to itself, other silicones, silica, and glass. If you need to release silicone from itself, use our mold release for silicone. In a pinch, a thin film of
petroleum jelly will provide a good release agent.
Silicone RTV mold making
rubber may soak into a porous surface and lock in place. This is often the
case when making a mold from a wood pattern. To prevent sticking, seal the
wood so the silicone can't soak into it. Krylon Acrylic spray is a good choice. It is compatible with just about any
substrate or silicone rubber. Silicone doesn't stick to Krylon Acrylic. Petroleum
jelly can work well as a wood sealant also.
Mixing
For the AM128 series, mix the silicone resin at a ratio of 100 parts by weight to 10 parts
catalyst. A digital gram scale is best. The AM125 series is mixed 1:1 by volume, not weight. Mix thoroughly. Since our silicone resin and hardener are contrasting colors, it is easy to tell when it is mixed well. Do not whip air into the mixture by being too vigorous or using a high speed
mechanical mixer.
If you have further questions about making
your mold, please call us toll-free 1(877)342-8860.
We also sell several accessory products for
our silicones:
- Extra catalyst
- Thixotropic catalyst for brushing onto vertical surfaces
- Food grade silicones
- Clear catalyst
- Accelerators for faster curing
- Colorants for custom colors
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