Advice on how to do silicone layers

[magentaleo]

Hi Everyone

I'm experimenting with building doll parts and am looking for advice on how to create layer of skin using different types of silicone.

Currently, I'm focusing on building a torso (just as an experiment for now). My aim is to use a layer of ecoflex about 2mm to 4mm in thickness for the outer layer of skin, then a layer of more durable silicone underneath, then finally fill up the remainder of the inside with foam.

I have a mold in two parts for the torso.

My main question is this - what is the best way to create these outer layers? If I just apply the ecoflex silicone with a brush to the inside of the mold, it runs and just ends up in a pool at the bottom. Some of it sticks to the mold in the correct place, but it's a very thin later. To get the 2mm-4mm thickness I'm after, it would take many, many coats. I know there are thickeners you can buy which allow you you paint the ecoflex on vertically surfaces, but they also reduce the softness.

Some users on this forum seem to have done projects with similar layers of silicone, so I'm hoping someone here can give me some advice.

[Rtechguy]

The best way to do it would be to pour your material into your mold but set your mold on a continuously spinning table so that it rotates the mold continuously Distributing your material on the outside wall of the mold therfore giving you an even layer of it over the entire mold. after that is dry you apply your second layer in the same mold. All you would need is an attachment point at the bottom of the Torso an attachment point at the top of the Torso with pipe running to bearings and then a motor to rotate the entire assembly continuously until the material dries. I am not sure about the viscosity of the material but the rotational speed should be fast enough to keep the material against the mold, but slow enough so it does not put the material on you and your house walls.

[MannequinFan]

Hi magentaleo, welcome to TDF!

I'm no expert with silicone but I think with only a few mm skin thickness, being a little less soft and more durable might be a good thing.
Here's a video from Smooth-On showing how to make suture training pads. They use a less soft skin (0030) with the super soft gel fat layer underneath.

https://www.youtube.com/watch?v=G6HdZpXdEiM

[magentaleo]

Hi! Thank you for both of your replies.

It seems I have 2 reasonable options to try.

1 - a rotational mold seems like a good idea, and I do have the skills to set it up. The full rotational rig seems like a lot of effort, so before I consider it, I think I'll try what I believe is called a slush mold. All I have to do is move it around occasionally, and then a lot when the silicone starts to set. I've tried it with a small mount on the inside of a disposable cup and it worked well.



2 - Having a more durable coat might be a good idea too. Maybe do some thin layers of regular soft ecoflex on the outside so that the skin feels right, then a more durable coat underneath.

[animals32]

Smooth-on has some great products. Will have to investigate them more.

[Space Buckaroo]

How did this turn out for you? I believe the multilayer is the best way to go.

[Siliconeman]

The original post is quite old in thread standards. I would like to hear also how this went.

Personally I would use more fast curing silicone to brush the layers. You can either buy fast cure silicone as is or buy separate chemical catalyst to speed up the process.

[Average Joe]

When applying silicone in layers, if it's not the exact silicone being layered then it may warp. Over the area of a limb or torso, the warpage could be significant. I'd recommend a test piece before pouring hundreds of dollars of silicone.
And this applies mostly to platinum, tin cure doesn't stick so well.