How to Make Silicone Molds of Complex Shapes

Today I will lead you to teach you step by step how to make complex silicone molds. Such complex molds are usually divided into two halves to make, which is what we often call male and female silicone molds. Today I'm using the mushroom cloud model, which is an atomic bomb-like explosion effect model.

mold application scene effect

Production process principle: Cover half of the master pattern with plasticine, and fill the other half with rtv-2 silicone rubber, remove the plasticine after curing, and pour the rtv-2 silicone into the other half of the master mold again.

mushroom cloud master pattern model

Tools & Materials:

1. RTV-2 Silicone Rubber (Tin cured silicone)

2. Vaseline release agent

3. Smooth wood

4. Screwdrivers and screws

5. Knife

6. Pliers

7. Plastic bottle caps

8. Plasticine

Production process

Step 1: Make a Suitable Box

According to the master pattern model, the thickness of the silicone mold should be 2.5-3 cm is more appropriate. According to this size target, we use wooden boards to build a suitable mold frame. The gaps around it must be sealed with plasticine, otherwise it will leak. Of course, you can also use hot melt glue to seal.

Make a Suitable Box

Step 2: Transform the Box

In order to save cost and minimize the amount of silicone, I added wooden blocks on both sides of the wider part of the upper part of the master pattern to reduce the volume.

Transform the Box

Step 3: Apply mold release agent

In order to make it easier to separate the silicone from the board after curing, we apply Vaseline release agent on both the master pattern and the board.

release agent

Step 4: Mark the Parting Line

The parting line is usually drawn at half the height of the model according to the master pattern, and the line is drawn with a marker, so as to correspond to the marked line when pouring liquid silicone.

mark parting line

Step 5: Prepare the rtv-2 silicone

Weigh an appropriate amount of silicone according to the correct ratio of rtv-2 silicone and curing agent. The silicone and curing agent should be mixed and stirred evenly. Due to the high viscosity of the tin-cured silicone, bubbles will be generated during stirring, so after stirring, a vacuum pump is used for defoaming treatment.

Prepare the rtv-2 silicone

Step 6: Pour in the silicone

Pour the prepared liquid silicone into the mold box. Note that the operation time after mixing the silicone and curing agent is only about 15-20 minutes, so the silicone must be poured into the mold box within this time.

Pour in the silicone

Step 7: Preset positioning holes

In order to better combine the two parts of the silicone mold in the later stage, we need to pre-set positioning holes on one half of them in advance, and the positioning holes are set on the periphery of the master pattern.

Preset positioning holes

Step 8: Pull out the plastic tube

After the liquid silicone is cured, pull out the plastic tube with the preset positioning hole.

Pull out the plastic tube

Step 9: Apply Vaseline

Since the silicone and the silicone are hard to be separated together, the mold release agent must be applied in place in this step, as well as the fixed holes.

Apply Vaseline

Step 10: Continue to pour the silicone

After applying the mold release agent, continue to pour the silicone into the other half of the silicone mold, which can be shaken slightly to make the air bubbles disappear.

pour the silicone

Step 11: Wait for curing

Tin-cured silicone rubber raw materials are usually cured at room temperature for about ten hours, and the longest is not more than 24 hours. If it has not cured within 24 hours, it is necessary to investigate the reason why the silicone does not cure.

Wait for curing

Step 12: Demolition and Separation

Remove the box, separate it one by one, and trim the excess corners of the silicone mold.



Step 13: Finish the Effect

The final effect is displayed.

Two-piece silicone mold

Combination effect


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