What can I use for a mother mold when rotocasting?

[proteus]

I'm looking to make a two-part mold of a full-size helmet, and I've been doing some research on what I should be using to mold and cast it. But, there doesn't really seem to be a consensus on what kind of materials should be used for a mother mold. So, I thought it would be good to consult the experts

My setup is as follows:
I've got a sculpture ready to be molded, it is made out of monster clay and sits on an ed head (plastic)
Molding with Rebound 25 silicone seems to be a good fit, so that's where I'm headed. The divider will be made of EM-210 water-based clay
When it's done, I'd like to cast it in semi-rigid resin, like Smooth Cast 57D
I am planning on rotocasting, so the silicone + mother mold should be fairly light. I am decently strong, so it doesn't need to be like the lightest thing ever, but reasonably light

So I'm not sure what to use. I've been looking at Free Form Air but I've also seen folks use epoxy resin + fiberglass. I think plaster is out due to weight. I can easily acquire Free Form Air, but not sure what to look for in epoxy resin. Anyone have any suggestions? Thanks in advance!

 

[thejoker1246]

I'm looking to make a two-part mold of a full-size helmet, and I've been doing some research on what I should be using to mold and cast it. But, there doesn't really seem to be a consensus on what kind of materials should be used for a mother mold. So, I thought it would be good to consult the experts

My setup is as follows:
I've got a sculpture ready to be molded, it is made out of monster clay and sits on an ed head (plastic)
Molding with Rebound 25 silicone seems to be a good fit, so that's where I'm headed. The divider will be made of EM-210 water-based clay
When it's done, I'd like to cast it in semi-rigid resin, like Smooth Cast 57D
I am planning on rotocasting, so the silicone + mother mold should be fairly light. I am decently strong, so it doesn't need to be like the lightest thing ever, but reasonably light

So I'm not sure what to use. I've been looking at Free Form Air but I've also seen folks use epoxy resin + fiberglass. I think plaster is out due to weight. I can easily acquire Free Form Air, but not sure what to look for in epoxy resin. Anyone have any suggestions? Thanks in advance!

i use plaster bandage for all my molds which are life sizes busts and i slush cast i dont find them heavy at all plaster bandage is super easy to use

 

[udog]

There are many options.
Polyester resin+fiberglass, epoxy+fbglass, Shell Shock+PlastyPaste, Acrylic Resin+fbglass, and as said plaster bandage.
For rotocasting I like Smoothcast 65d.

 

[udog]

You can also use PU resin with Polyfibre (Polytek) for mold shells, works fine. Easy, fast and lightweight.

 

[djgillstudio]

I am new here,
I have used plasti-paste from smoot-on, and I have also used their Foam-it series, rigid foam, but one small thing with using foam, mixing and temperature is needed for full expansion, its rigid and very light. I will post some of my pictures of what I have done.

 

[djgillstudio]

Here is Face and silicone ( mold max silicone tin) with outer mold with rigid foam