Heatproof Moulding Material

AMirth

New Member
Hi all!
Been mask making for a while but recently got into polymer clay and LOVING IT!
The one issue I face is well... the face. When I used to make masks I’d pepakura my own files or model and print them using a CAD representation of my head. Not a scan, but a rather accurately sized model.
The problem is, if printed, I could use it for modelling but not for baking, and the masks certainly would benefit from the support.

So I’m going to make a basic tape pattern of my head and I plan to use it to roto-cast a bust skin and reinforce that with more material. My question is: what’s the best pourable oven proof material to make this skin? Would it be best to make a silicone skin then fill it with clay or something?

Thanks!
 

udog

Active Member
Hi
I´m not sure what are you trying to achieve.
You want a shape to model on it (with what material?)and then bake it?, and you are saying the shape would have a silicone skin?.
What temperature will the material have to stand?
There are thermostable resins and platinum silicone can stand some heat but I don´t understand what you are after exactly.
 

Chaank

Well-Known Member
The best way to go would be use oil or water based clay and take a mould of it then you have a huge variety of materials you could cast it in
 

AMirth

New Member
Hi udog. Yes, I want a shape to model on. “With what material?” Would be polymer clay, as mentioned in the original post. The “shape” doesn’t have to have a silicone skin, I thought of that as a good way to capture detail from the initial mould.
The temperatures it would have to survive are standard oven temperatures (50-200°C) but mainly at the 130°C mark.
I figure that high temp plaster may be the best material. I can slurry it around inside the mould and then fill in the rest with stiffer plaster and filler material.

Edit: what I’m after exactly is a material I can slurry inside a negative mould in order to make a positive mould that I can use as a base for sculpting, that must be able to withstand standard oven temperatures for prolonged time over many uses.
 

AMirth

New Member
The best way to go would be use oil or water based clay and take a mould of it then you have a huge variety of materials you could cast it in
I’m not entirely sure I follow what you mean. I have a negative, I need to make a thermally stable positive from it. Being able to slurry it around the negative is important to capture the detail.

Edit: so I figure high-temp plaster is a good bet?
 

Chaank

Well-Known Member
Yeah sorry, after reading my comment back again I can see I wasn't very clear at all. I mean, rather than using sculpy, use an oil or water based clay. Then you wont have to worry about baking. You could also use something like milliput or epoxie sculpt. Again, no baking. Sculpy is great but for a mask, I would be concerned about how strong it would be.
 

Chaank

Well-Known Member
The reason I say this is first, polymer clay is strong as a small solid shape but with any part with leverage on it, like the bowl shape of a mask damage is very likely. Also, when using a plaster buck to sculpt on, the plaster would have to be dried slowly to remove the moister it has absorbed before you raise the temperature otherwise it would crack. I would imagine most masks are built on a buck (head shape cast) and then moulded in place and cast. If you did that, you could just slush cast the final mask in resin which is incredibly strong even if it is thin
 

AMirth

New Member
l mean, rather than using sculpy, use an oil or water based clay. Then you wont have to worry about baking. You could also use something like milliput or epoxie sculpt. Again, no baking. Sculpy is great but for a mask, I would be concerned about how strong it would be.
My worry here is the curing time and the strength of the final unbaked piece. The same goes for milliput and epoxie (for curing time at least). I like to have a long time to tinker over the finer details but then I get impatient waiting for the final cure!
I’ve gotten one mask in polymer clay at the moment which is holding up just fine, even with thinner sections and a feature that creates a natural stress focal point.

I went the polymer clay route to deliberately not have to create silicone moulds and cast masks that I’ll be making once and only once.
I have wire mesh and just plain wire to help strengthen it where necessary.
The cracking plaster I can deal with by using a high temp plaster such as that used in fireplaces. It’s designed for the heat and shouldn’t crack as regular plaster would. Plus sticking it in the oven at 50°C for a good while to help dry it out beforehand upping the temperature would help. Then glaze it.
 

udog

Active Member
The best way to go would be use oil or water based clay and take a mould of it then you have a huge variety of materials you could cast it in
That would be my option too. Mold your positive shape and cast an polyester or epoxy+fiberglass shape. There are also thermostable versions of these resins.
Never used high temp plaster, could be an option but can´t say how it works as a casting material. I think fiberglas would give you a more durable casting. Also, more light weight than a full plaster piece.
Just curious, once you bake your sculpt (made over the rigid shape), will it come out? no lockings?...doesn´t the polymer clay have a contraction of some kind?.
I still don´t understand what is the goal of your project.
 

clonesix

Sr Member
Amirth, welcome to the forum. Many questions can be answered here if you know what you are looking for, and know how to write your question. I had to read you post several time to understand what you are asking.

It appears to me that you are asking how to make a face cast, onto which you plan to sculpt your masks. Is this correct?

Face casting needs to be done by an experienced person. If done wrong, it can be very dangerous to the person being cast.
Here is a youtube video that give s a good explanation:

You best material that you can put into the oven and bake is Hyrocal gypsum plaster. It is inexpensive and available most places. It will take oven heat well/
 

Chaank

Well-Known Member
The strength of milliput and epoxy sculpt wouldn't be an issue at all. You can also work it before, during and after curing. This means you can still stay away from mould making. But if you still want to go the route you are asking about the name of the product you are looking for is refractory cement. Still, an heat proof materials will prevent you from getting even heating. Have a look at Bruce d Mitchell's masks. They are all made with epoxie sculpt
 

AMirth

New Member
It appears to me that you are asking how to make a face cast, onto which you plan to sculpt your masks. Is this correct?
/
Hi and thanks. No, I don’t need to know how to make a face cast safely, that’s something I’ve been aware of since getting into costume prosthetics back in highschool. I don’t need anywhere near that level of detail anyway, just dimensional accuracy.
The negatives I have. The positive I was thinking would be good to cast in high temp plaster, as you say. Though I’ve discovered my gap filler is fine in the oven and bakes rock hard so I may end up using that as its on hand. We’ll see.

Thanks!
 

AMirth

New Member
The strength of milliput and epoxy sculpt wouldn't be an issue at all. You can also work it before, during and after curing. This means you can still stay away from mould making. But if you still want to go the route you are asking about the name of the product you are looking for is refractory cement. Still, an heat proof materials will prevent you from getting even heating. Have a look at Bruce d Mitchell's masks. They are all made with epoxie sculpt
I know the strength won’t be an issue. How does one work milliput before curing? To my knowledge milliput is a two part that is kneaded together and begins to cure as soon as the chemicals react, so you’re pretty limited.
Working it after is just like carving and filing most other media that have similar properties, but the general shaping is best done before, and it seems to me there isn’t that much “before” time. I’d like to work on my masks over several days, not rush to complete them in a few minutes.

A heat proof material would indeed create a thermal barrier depending on its thermal transfer coefficient, but the entire outside of the mask would be open to air. It takes 15 minutes per 6mm thickness to cure and multiple cures only help to strengthen it, though it can eventually singe or discolour, which isn’t an issue as I paint them anyway. So really, sticking it in for longer at lower temp is fine with me.

But if there’s a chemically cured polymer “clay” that gives me plenty of working time (hours to days) then I’m in!
 
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