Facial prosthetic plaster mold making

[kimidori]

Hi everyone, I'm new here and a first-time challenger for making facial prosthetics. I was going off of several tutorials to get started, but it seems I've encountered a problem and I'm stuck. Could you give me some advice?

Here's what I've done so far:

1) Made a plaster face cast. Once completely dried, I sealed its surface with a few coats of modge podge.

2) I used air-setting clay to build my sculpt onto the face cast.

3) Once the clay sculpt was dry, I applied a thin layer of vaseline, and then several thin coats of liquid latex.

4) Here's where it got hairy: I am at the point where I want to make a negative mold of my sculpt. Rather than doing the pouring method, I saw in a tutorial how you could essentially pile up plaster on top of the sculpt in layers. I started by applying a thin layer of vaseline to my sculpt, then 4 thin layers of liquid latex. Then, I mixed some clumpy plaster, and then layered it on top of the latex. For the last layer, I applied some plaster gauze so the fibers will keep the mold together. (see my photos below)



I had to leave it for several days because of time, but when I went back to it, the plaster mold would not come off the face cast. The latex did prevent the outer plaster from sticking, but I literally had to break off the outer plaster mold to get the cast out. It's a challenge because I need to keep the face cast in tact, so that I can remove all the clay and use the original cast for when I pour the silicone.

Alternatively, I tried a dish soap method that someone suggested, and for that time I tried removing the outer plaster as soon as it seemed fit enough to hold its shape....but that proved to be the same result.

So many people swear by vaseline, but it's really not doing the trick for me. Anyone have an alternative mold release that they'd recommend? Or is there something along the way that I'm doing wrong? Any help would be greatly appreciated!!

(For anyone who's curious, I'm making this for my outfit of Baron, from Ghibli's "The Cat Returns.")

 

[Mr Mold Maker]

Allow me to be blunt here...You've made quite a few mistakes along the way.

Let's try and go in order..
I've never come across a lifecast sealed with Modge Podge. That could be a reason they halves stuck together but I'm not sure. Next time, I'd just rub a thin layer of vaseline into the stone and start sculpting. There is no reason to seal the stone.

You used air drying clay. That is typically avoided in prosthetic work because you have to go so thin, particularly on the edges. When the clay dries it will shrink and crack. Next time, try Chavant NSP medium. It is an oil based clay so it won't dry out and will not inhibit silicone.

On to inhibiting silicone.. You did the one thing you should never do if you want a silicone appliance. You applied latex directly to the mold! I don't know why you thought applying latex to the sculpt was a necessary step, but in doing so you've backed yourself into a corner. Platinum silicone will NOT cure in a stone mold that has been in contact with latex. The only option you have now is to encapsulate the silicone and pray it's enough not to inhibit, or buy some Inhibit X from Smooth-On. Inhibit X comes with it's own set of challenges, mostly releasing it properly.

On to the mold. Again, the application of latex wasn't a good idea. Normally you'd seal the sculpt, apply a release (such as vaseline or a spray release) and then mix your stone and apply it. Your stone should never be "chunky." You want a smooth milk shake consistency. No bumps or lumps. If it's "chunky" you have unmixed stone. You'd also be better off using burlap for the reinforcement, and it goes in the second the last layer. It won't do much on the outside of the mold.



I don't know what tutorials you've been watching but I'd suggest you stop immediately before learning bad habits! Check out the Stan Winston School, they have fantastic tutorials and they teach you the correct way. If you can't afford or don't want to purchase them, check out Stuart Bray on youtube. He is a working effects artist and teaches very effectively. https://www.youtube.com/user/stuartbray73

 

[kimidori]

Thank you SlipKnoT, all your points are incredibly helpful. I'm sorry and I ask that you please bear with me as this is literally the first time I've ever done this. I will probably start over from scratch as it seems it will be easier than back-tracking at this point. Stuart Bray's tutorials are easy to understand and I'll definitely try his sculpting methods.