# Alternative to Plaster of Paris



## lonerogue2 (Sep 30, 2008)

Heya guys,

I just made a cast of a decent sized skull from plaster of paris. (pics to come a bit later when i dries more) the only problem is because its a decent size, it weighs about 8 pounds or so. So my question is, is there anything that acts like plaster, but is much lighter? I tried looking some stuff up online but cant find anything general, might need a specific product name. 

So if anyone has used something lighter than plaster for casting, give me a shout  im trying to stay away from expanding foam, as im not sure the mold im using could take it. thanks everyone 

Bob


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## DeathDealer (Jun 18, 2004)

What about resin with a hollow sphere filler?
You could also look at rotocasting to create a hollow cast.

edit: Found the wood rotocaster.
~Rotomolder~ Solsylva CNC Plans


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## Bubbels (Nov 30, 2008)

How about silicone caulking as is discussed here: http://www.halloweenforum.com/general-halloween/75958-silicone-molds.html

Been dieing to try it, just have a long list of things to finish before I can start something new.


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## lonerogue2 (Sep 30, 2008)

Hey death, thats an idea, but a costly one. I guess i want the best of all worlds, cheap and light  might look into it though.

Thanks bubbles, i remember reading this thread too, but i have the mold. Im not sure filling the mold with silicone caulk would do the trick, but who knows


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## Bubbels (Nov 30, 2008)

I misunderstood. In that case, expanding foam does the trick quite well! Not only are they light, but you can kick them around without worrying about breaking them and I would imagine they are also rather water resistant.


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## nightrideproductions (Jun 1, 2008)

Did you consider this:
Rigid and Flexible Castable Foams | Smooth-On, Inc.
[Edit: Just noticed the stuff is pretty expensive, but it says it expands many times its own size, do idk]

I wouldn't suggest spray foam, or "Great Stuff." I used that at first for the thread mentioned above, and there were no problems with sticking, but as the foam was curing, it seemed to shrink from the inside, which deformed the entire cast after a few days.


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## lonerogue2 (Sep 30, 2008)

Hi Nightride,

yeah i just noticed the price too. That stuff is perfect, but way beyond my budget  why is all the cool stuff so expensive lol. drats.


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## wilbret (Oct 8, 2004)

Get some minimally expanding spray foam. AKA Great Stuff or another brand.


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## Bubbels (Nov 30, 2008)

nightrideproductions said:


> Did you consider this:
> Rigid and Flexible Castable Foams | Smooth-On, Inc.
> [Edit: Just noticed the stuff is pretty expensive, but it says it expands many times its own size, do idk]
> 
> I wouldn't suggest spray foam, or "Great Stuff." I used that at first for the thread mentioned above, and there were no problems with sticking, but as the foam was curing, it seemed to shrink from the inside, which deformed the entire cast after a few days.


Did you use enough foam? I figure I use a little more than a half can per skull, havnt seen the shrinking effect problem that you are talking about.

You also got to let them sit for at least a day if not two before you pull the mold.

All in all, I wouldnt rule it out until you try it lonerogue! At $3 a can its worth a shot.

Here is the video I followed with the exception of making a PP mold versus the cut in half skull he does.

YouTube - Cheap Easy skulls


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## nightrideproductions (Jun 1, 2008)

Bubbels said:


> Did you use enough foam? I figure I use a little more than a half can per skull, havnt seen the shrinking effect problem that you are talking about.
> 
> You also got to let them sit for at least a day if not two before you pull the mold.
> 
> All in all, I wouldnt rule it out until you try it lonerogue! At $3 a can its worth a shot.


I used about that much foam. I dunno what happened, but it just seemed like it shriveled up. I let it sit for a little more than a day. I might try it again just to see


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## wilbret (Oct 8, 2004)

Great video. 

I wonder if he makes more than one skull to use up a can in one sitting? Great Stuff is pretty much use it or lose it, in my experience.


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## lonerogue2 (Sep 30, 2008)

*might give it a whirl*

Yeah, looks like i just might have to give it a try. from all my readings I agree, you either love the great stuff, or you loath it. Looks like i might have to cast my lot and see which group i belong to. I'm just worried about ruining my mold. might have to give the ol foam a go. I'll let you guys know how it goes.


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## voodoo willy (Feb 1, 2008)

The two part rigid foam from smooth on is Great!!!! It seems like alot of money but at first
but it goes a very long way. I use it for just about all of my skull cast and I haven't had a problem yet. 
You can try the trial size if money is an issue, and you should get several castings from it.
Go with the 3lb it expands the most and still picks up detail.

It also sets quick so you can crank out many, many castings in a few hours.


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## Bubbels (Nov 30, 2008)

wilbret said:


> Great video.
> 
> I wonder if he makes more than one skull to use up a can in one sitting? Great Stuff is pretty much use it or lose it, in my experience.


I just do the one, mainly because I haven't built a second mold. Would be handy because the major downside to this process is that you cant crank out skulls very fast. My experience with losing the foam is that if you let it sit for a couple weeks then you got to throw it away. However, when you use it that second time a couple days later the foam comes out much slower. Takes you 10 minutes to fill the skull versus 2.


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