How to make a rigid epoxy mold compatible with platinum silicones

As we know, platinum silicone is a very flexible and elastic material with a remarkable ability to reproduce large quantities of pieces, such as reborn dolls, Sex Dolls, masks, any replica requiring hyperrealism, and more.

However, working with this type of silicone comes with a drawback: it has very specific characteristics related to inhibition problems. For this reason, if you want to take advantage of its excellent qualities, you need to use a mold that is compatible with platinum silicones.

That's why, in this Feroca article, we'll walk you through the step-by-step process for making a small, one-piece rigid Epoxy mold that is compatible with platinum silicones. However, the same approach can be applied if you want your figure to have a mold on both sides.

Step-by-step video guide for making a rigid Epoxy mold compatible with platinum silicones

Tutorial for making an Epoxy mold suitable for platinum silicones

Materials for making the Epoxy mold

Epocoat Grey Epoxy Resin

One of the favourite products in the workshop of our subject matter expert, Juan Villa.

One of Spain's leading references in the creation of props, replicas of fossils, archaeological pieces, museum figures, and countless other masterworks.

Thixotropic Epoxy resin, which makes it a gel coat. Hard, resistant and very stable. Suitable for a wide range of applications, including vacuum forming molds, injection molds and FX molds for silicone casting, precision tooling, and more. As you'll see, it's a multi-purpose resin.

Axson SC-258 Epoxy Putty

This lightweight Epoxy putty will be used to reinforce our mold. It's a fantastic paste-putty, very strong and at the same time extremely lightweight.

You'll find it has some really interesting properties for making this type of mold, especially in small to medium sizes.

Also remember, as stated in the product specifications, to use a mask, gloves and all necessary protective equipment.

Step-by-step guide to creating your mold

Before making the mold, you'll need to sculpt your piece. To do this, use Monster Clay professional sculpting clay. Once your piece is sculpted, you'll be ready to create the mold. Think of this as step zero.

Setting up your work area

• The first thing to do is prepare your work area. Place a small piece of plastic on a table and set your sculpted piece on top of it.

• If you're working with, for example, a larger sculpture or a sculpture in the round, you would need to divide it into two parts — first doing the top half and then the bottom half.

• Also, make sure to keep all the tools you might need within reach, such as a scale, a craft knife, a sculpting tool, a mask, gloves, etc.

Preparing the Epoxy gel coat

• To do this, you first need to mix the Epoxy gel coat, Epocoat Grey, in the correct ratio. It comes as a two-part system, part A and part B.

Specifically, the ratio is 100 to 15, but don't worry — this is clearly stated on the product data sheet and you can also find it on the Feroca website.

In addition, these containers are clearly labelled with working times, ratios, and more, making them much easier to use.

• In this case, we're going to make a small amount. You'll only need 100 grams of part A, which you'll then catalyse using 15 grams of part B.

• Mix thoroughly, making sure everything is well blended along the sides and at the bottom of the container. After this step, your gel coat will be ready to use, with a very pleasant consistency.

Registering the piece

• Once you have the mixture ready, apply a first registration coat over the entire piece using a brush to ensure it picks up all the fine details.

• This resin has a working time of approximately 40 minutes, though this will depend on the climate.

• Although its full cure time is 16 hours, it will start to polymerise in approximately 30 minutes, allowing you to add the next coat. But first, apply a small amount, let it register well, and then build up subsequent layers to increase thickness.

You can also use this step if your piece needs specific registration keys. This will depend on its shape — as we know, no two molds are exactly alike, and no two sculpts are identical.

In other words, what matters most right now is that the resin registers every detail of the sculpt perfectly.

• Next, you need to wait for the Epoxy resin to polymerise.

Reinforcement layer with putty

• Next, we'll use our lightweight putty to add reinforcement (this is a great alternative to applying additional coats, depending on the type of model) and to give the mold a perfect finish.

The Axson SC 258 lightweight putty has a fantastic quality — it's practically weightless and very easy to work with.

• Mix equal halves: half of one component and half of the other, measured by volume.

• Once you have equal parts of part A and part B, mix them together. Having a little water nearby will help you smooth it out and can also make it easier to blend both parts together. However, in this case, add only a very small amount, as too much could make it overly sticky.

• Make sure to check there are no colour streaks and that everything is fully homogeneous.

• Use the resulting putty to reinforce the mold. To do this, cover the entire piece, pressing firmly so it adheres well to the registration layer. You can use a little water to smooth it as you go.

• At this point, if you like, you can write a name or number to remind yourself what's inside, what type of mold it is, for storage and organisation in the workshop, etc.

• You have a working time of 40–50 minutes, though as you know this depends on temperature and may be reduced to around 20–30 minutes. Its full cure time is around 7 hours.

• If the piece is larger, you could use fibreglass fabric to reinforce it and laminate it with an Epoxy resin. That is, when working within the Epoxy family, you can laminate a reinforcement fabric using an Epoxy resin as well.

Obtaining and perfecting the mold

• Next, let it dry and harden.

• Once that time has passed, your lightweight Epoxy putty will be completely rigid. You'll have a very strong yet lightweight mold.

• The next step is to finish cleaning and perfecting the mold. To do this, remove the Monster Clay from the inside using a sculpting tool or wooden tools.

• You can also use a little solvent to remove any remaining traces of clay.

• Then go over any other details and remove any flash with a craft knife or sandpaper.

The result will be a compact mold with perfect registration, lightweight and fantastically solid. It's compatible with platinum silicones and ready to use.

Find the best molding and sculpting tutorials at Feroca

At Feroca we don't just focus on selling — we also want our potential and existing customers to receive the best pre- and post-sales experience possible. That's why we offer a wealth of resources across our platforms to ensure our products are used correctly and so you can discover all their endless possibilities.

Video tutorials, articles, WorkShops, live videos on social media and more, led by our experts, so you can learn more about the art of molding and sculpting with Feroca. Browse our website and social channels to discover them.

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