Form rubber

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One way to make a puppet with a soft material such as human skin is using a material called foam rubber. Make a mold with plaster or silicon, foam the foam rubber with a mixer, pour it into a mold, and heat it in an oven to make a soft outer skin like a sponge.
However, the difficulty level is quite high, it is a method that can not be done well at once by using a professional modeler who baked many times and chooses the one with the best condition. You should make many times, the material cost will also change accordingly. Temperature and humidity are greatly influenced result, so you should measure the temperature and humidity as you work, and keep it as data.
There is a method of baking after framing a armature in a mold beforehand and a method of baking only the foam rubber and then filling in the armature afterwards. In here I would like to introduce a method of baking only the form rubber .

materials and tools

foam rubber
Here I use the form Rubber set of Resetex Corporation in Japan.

It is high strength with resin.

oil-based clay
use for prototype of a puppet with rigid objects for modeling.

Use it when foaming foam rubber. I am using a hand mixer that is commercially available. The rotating parts at the tip is called a beer, you should use a wire not like a plate, the probability of successfully preparing the foam finely increases.

It is used for baking the foam rubber with the mold of plaster. There is another way to use a steamer or put it in hot water.
Used to bond foam rubber.

parting agent
It is used for making mold of plaster. vaseline or potash soap.

It is aqueous acrylic paint. Used to color foam rubber. It is also possible to spray and dilute with an airbrush.


Make a frame work with aluminum wire or iron wire and wind hemp thread so that clay can easily be attached. When baking only the foam rubber, it will shrink when drying, so make it slightly larger.

Prepare a prototype with oil clay.

Take a mold of the prototype. Lay down the prototype and fill around with lightweight oil-based clay. Think about where to put the boundary line of the mold at this time. Bring the boundary line to a less obtrusive place.

surround it with a foam core board.

Pour plaster. Work carefully and quickly so as not to enter bubbles. Pay attention to the thickness of the mold. If the mold is too thick, heat will not be transmitted to inside, and if it is too thin it will crack during work. Try ourselves over and over and have experience.

After the plaster solidifies, remove only the lightweight clay and surround the mold with a foam core board again. Do not forget to apply a release agent so that plaster does not stick together.

Pour plaster like the first.

After plaster solidifies, divide the mold into two pieces and take out the prototype. If clay remains, clean it thoroughly with a cotton swab soaked with thinner. Leave it as it is for 1 or 2 days to dry it.

Take foam rubber (Solution A) only in an appropriate amount into a bowl and foam it with a mixer. First mix the foam rubber at high speed for about 2 to 3 minutes, then turn it into low speed to make a fine foam.

Measure Solution B (10% of Solution A) and Solution C (5% of Solution) and mix with Solution. Curing begins when mixing, so work quickly.

Pour the foam rubber into two molds. Be careful not to get bubbles in this work.

Quickly superimpose the two molds.

Put it in the oven and heat it. The standard is around 2 hours at 100 degrees, but depending on the size of the prototype and the thickness of the mold, I think it would be better to bake it a few times and try it.

Wait for the mold to cool down and remove the foam rubber.

Cutting off the protruding part, wash the foam rubber thoroughly with water and dry it.

To put the armature in foam rubber, cut it with scissors according to the seam and hollow out the inside. Work carefully so as not to make a hole by mistake.

It is difficult to predict exactly how the foam rubber shrinks, so keep the armature in a temporary assembled state and fine-tune the position of the joint of the armature while fitting it to the foam rubber.

After the position of the joint is decided, weld and assemble the armature first.

Put the armature to the foam rubber, then apply bond at the cut section and glue it.

Color it with paint for soft vinyl or rubber.

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