# Skull Mold for Urethane Application



## BobC (Aug 23, 2005)

I finally tackled a project I had wanted to do for many years. I have read books and talked to other haunters on their process for making copy's of skulls. Everyone seemed to pull me in 100 different directions which confused me to the point of putting the project on the back burner. I opened a thread a few weeks ago asking for help with mold making and a few of you replied to my call "I thank you". I shortly after received a PM from Scourge999 who pretty much walked me through the whole process. And to whom I credit for having an awesome mold now. I wanted to post this process for anyone that is or was in my shoes for many years. It is a simple process that takes about two days to complete. Have Fun.

I started with a Bucky skull and using (Magic Sculpt) filled in all of the holes around the skull. Eyes, Nose, calvarium, Making the skull solid. Make sure Everything is closed off because you will be putting brushable silicone over this. If there are any major holes the silicone will keep seeping in and make it impossible to get the silicone off the skull when dry. ((Some hot spots not to ignore are the side of the skull right behind the jaw and under the jaw in the front)). Smooth the clay with water and Let Magic Clay dry overnight.










Next you need to get a piece of plywood or in my case I used Osb board cause I had it laying around. And Drill a 1 3/4" hole using a circle bit. This will be used for pouring your two part urethane foam later.









Then you want to Center your skull over the hole you just drilled. If you are casting a Bucky skull like I did ignore the hole that is already on the bottom the holes do not need to line up. Outline your skull with a magic marker onto the plywood and hot glue your skull onto the drawn outline.










Make sure your skull is clean of dirt and dust. Then apply Rebound 25 which is brushable Silicone Rubber from Smooth-on. http://www.smooth-on.com/ I eye balled the amount I needed to cover my skull in large plastic cups. mixing part A & B together. Mix a few minutes until the color of the silicone is uniform then apply with a small cheap paint brush. The 1st coat should be light and cover all the details on your skull. you will want to bring the silicone down onto your plywood also a few inches as seen in the photos creating a large lip.










The Silicone must then dry for 60 minutes, or until it is sticky to the touch.
Then it is time to apply the second coat of Rebound 25. On the second coat I added about a tea spoon of Silc Pig in with my Silicone which is a dye that colors the silicone. I did this so I was certain not to miss any areas that I had to cover. I used Blue there are many colors to choose from. Mix it up and slap it on.










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## BobC (Aug 23, 2005)

Then you must wait another 60 minutes to Apply the 3rd coat in the same manner. Only this time you are adding another product called Thi-Vex II which is a Silicone thickening product. I believe you add 4 drops to every liquid ounce of Rebound 25 that you use. A small amount goes a long way. Mix this all together and concentrate the 3rd thicker coat on areas like the eyes,nose, and mouth fill them in solid and use the left overs to cover the other areas of the skull and plywood.



















After the 3rd coat your skull should have plenty of Rebound 25 on it. You could do one more normal coat if you want to but it isn't needed. let your skull dry overnight. And then with a sharp razor knife cut the Silicone around the skull in a circular fashion leaving about a 2" lip.



















Then it is time to flatten out some Sulfur free clay. (Scourge999) recommended Klean Klay which is great. But I used a Chavant product for this skull which was very hard to work with. Cut flat 1/2" slices of your clay, bond them together with your fingers and apply it running down the center of your skull. With the back end of a paintbrush or toothbrush press the clay onto the skull sealing it. You only need to do this on one side. This will create a wall for the next step which is a hard plastic shell.










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## Dark Angel 27 (Sep 11, 2008)

where's the next part?


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## BobC (Aug 23, 2005)

After your Clay Mohawk is in place you will want to spray or brush down your plywood wood and clay Mohawk and even the skull if you wish but it isn't needed. I used Ease Release 200 which comes in a spray can and works great.










Then it is on to the Final process which is Plasti-Paste. This is trowel-able plastic in liquid form that when mixed turns super hard when dry. This will be your outer shell. You will mix this in a 2 to 1 fashion. 1 part A and 2 parts B. I filled up two large plastic cups with part B and one of the same cups with part A dumped everything into a large mixing container and mixed about one minute until the color was uniform a weird yellow. Then take a paint stick and apply your mix (To one side only) onto the skull and the clay wall making sure to go over the latex flange onto the plywood about 2" past your silicone.




























After the Plasti-Paste is applied you will need to let it dry for about 90 minutes. After 90 Mins remove your clay Mohawk and clean up the surface good. Spray down the whole area again with your release agent and Apply Plasti-paste to the other side.


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## BobC (Aug 23, 2005)

Which will look like this..










After 90 minutes when this dries you will want to drill 6 pilot holes on each side of your mold through the dried Plasti-Paste flange into the plywood. Later you will apply 12 -1" wood screws into the holes to hold the mold onto the plywood while you pour your 2 part Foam. After you drill these holes drill 5 -1/4" holes around the mohawk wall through the Plast-Paste. you will apply 5 -1/4" Car-rage bolts with 1/4" washers on each side and tightened with a wing nut. But before you apply any screws and bolts and after your holes are drilled separate your shell from the plywood and Silicone mold. At this time the edges of the Plasti-Paste will be very sharp. I cut my finger pretty bad. So you will want to clean up the edges with a cutting wheel or Dremel tool sand or cut all the edges flat. This will make the mold easier to work with. Then remove Your silicone mold from the skull by working it from back to the front. Don't be afraid to pull the Silicone its pretty strong stuff.



















After this you will insert your Silicone mold back into the shell and screw and bolt it down to your plywood. as seen above. Flip the mold over revealing the circle you cut into the plywood earlier and set it into a small bucket or garbage can. You will want to cut a small square piece of plywood to cover the hole after your pour your 2 part foam. Set that over the hole and pre-drill 2 holes you will screw this down to lock the foam inside the mold. Mix some 2 part foam which will take some trial and error to get the correct amount depending on what size skull you are casting. After you pour your foam secure your small plywood square down over the hole and shake and rotate the mold around in circles to get the foam into tricky areas in the mold. Then set it down upside down on your bucket or garbage can and you can de-mold your foam skull in about 2 to 3 hours. I hope this helps someone. Have Fun


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## Dark Angel 27 (Sep 11, 2008)

nice! that's absolutely awesome!


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## BobC (Aug 23, 2005)

I would like to thank Scourge999 for walking me through this process. Its so great that us haunters help each other out. And also big shout outs to Jameson Irish whiskey, Coors, and 89.5FM NJ's Heavy Metal radio station for getting me through this project. Enjoy everyone. :jol:


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## niblique71 (Dec 2, 2009)

Damn I want to do this!!! It's a good thing you didn't mention it at the Mnt, I'd have shut off the fog machines and picked your brains. Thank you for that tutorial.... AWESOME... Still gonna pick your brains...


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## BobC (Aug 23, 2005)

Pick away..lol


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## My CReePY Garage (Jun 7, 2010)

Very nice.
Is it paintable? Carvable, if you wanted to add more detail?


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## BobC (Aug 23, 2005)

Yeah you can paint it carve it sculpt clay on top of it to flesh it out anything pretty much.


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## NoahFentz (May 13, 2007)

It was great finally sitting down and chatting with you this past Make and Take. That's what I like about the dinner aspect too. After a day of prop making there is time to sit and eat and share stories about Halloween.

Great step by step process. thanks for posting it.

I am interested in doing this process....eventually. I can see why I dont think we could do a make and take but it would be cool to see the process of making the foam skull. I do like the fact that they are much durable and can be manipulated afterwards its just the cost factor. After creating the mold and buying all the materials, How many skulls do you have to make to break even?


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## Denhaunt (Aug 18, 2006)

Excellent Tutorial. My trial and error attempts have been mostly error but now I see where I was screwing it up. Thanks.


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## beelce (Jul 21, 2007)

nice how to Bobc....thanks


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## Bascombe (May 18, 2010)

Excellent tutorial. You didn't leave any bits out that would make us scratch our heads.

Good work!


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## RoxyBlue (Oct 6, 2008)

BobC said:


> I would like to thank Scourge999 for walking me through this process. Its so great that us haunters help each other out. And also big shout outs to Jameson Irish whiskey, Coors, and 89.5FM NJ Heavy Metal radio station for getting me through this project. Enjoy everyone. :jol:


I love this picture - it's a total hoot

Well done tutorial! Seeing pictures of each step is extremely helpful.


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## DarkShadows (Feb 6, 2006)

BADASS! I did the same method making my skulls... Toby from haunt 31 used my mold at Great Lakes Fright Fest, which is made using the same smooth on products.

What foam are you using that takes 2-3 hours? I'm using Foam-it 5, and it takes about 5 minutes to be completly cured. I just clamp the shell together, flip the mold upside down, and pour the foam. I dont do the last part you did by clamping it on the plywood board, seems like it would take alot of time to mass produce skulls.. Looks good tho man, props!!


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## fick209 (Aug 31, 2009)

excellent step by step tutorial, very well done


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## BobC (Aug 23, 2005)

DarkShadows said:


> BADASS! I did the same method making my skulls... Toby from haunt 31 used my mold at Great Lakes Fright Fest, which is made using the same smooth on products.
> 
> What foam are you using that takes 2-3 hours? I'm using Foam-it 5, and it takes about 5 minutes to be completly cured. I just clamp the shell together, flip the mold upside down, and pour the foam. I dont do the last part you did by clamping it on the plywood board, seems like it would take alot of time to mass produce skulls.. Looks good tho man, props!!


I use foam-it 15. I want to give the others a try to see what works best for me. 
Thank you everyone for the kind words I really hope it helps.


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## Bone Dancer (Oct 7, 2005)

Excellent job on the how-to and great photos, very well done.
What kind of money are well talking here for what you showed us?


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## BobC (Aug 23, 2005)

Around $200. I bought everything from Smooth-on. It might be Cheaper with another company. US Composites http://www.uscomposites.com/products.html is another place I have ordered foam from I know they carry mold making supplies not sure about their prices though. I have heard in my research that you could use normal store bought Silicone from Home Depot or Lowes for the Silicone process which would lower the price. :jol:


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## DarkShadows (Feb 6, 2006)

The thing with the store bought silicone is that its extrmely fragile. Sure the smooth-on mold will cost more, but in the long run will save you time and it will last. We used my mold for Haunt Club Chicago make/take and it had atleast 100 pulls and still looks brand new, verse using my silicone caulk mold and only had 1 pull before it tore..


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## IMU (Apr 8, 2009)

Thanks for this, maybe I'll actually try and make one this year.


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## Jaybo (Mar 2, 2009)

Great info! I did not know they had foam that cured in 5 minutes! That puts a whole new spin on things. 

One question though, how would you go about making a mold for a more complex item. Like an elongated skull with a large open mouth? Would it be easier to mold separate pieces and then assemble them afterward?


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## BillyC333 (Mar 13, 2010)

I'm going to mold two thumbs up and send them your way for this tutorial


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## BobC (Aug 23, 2005)

Jaybo, If the jaw is detachable you would either hot glue the jaw in the position you want to cast and fill the mouth in with clay. or make two separate molds if you want freedom with the jaw to move freely. :jol:


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## The Watcher (Sep 13, 2008)

BobC That was a very nice skull you had at the m&t. It seemed like these will be durable also. It helps seeing the process with the materials to understand it better. Thanks.


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## BobC (Aug 23, 2005)

Thanks Watcher, it was so great that you came up to see us. I didn't get to talk to you as much as I would have like to. The Entertainment was top notch I really enjoyed it. I'm happy for your safe return home and I Hope you can make it back again sometime. :jol:


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## HauntCast (Jul 25, 2008)

Denhaunt gave me a taste of casting back in January. Next year I'm going to try a few projects on my own. 
Great tutorial. Rock on!


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## pagan (Sep 9, 2009)

Great job on the tutorial! Nice looking skull, too!


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## RavenLunatic (Jan 3, 2006)

great tutorial, funny pic


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## SPOOKY J (Nov 20, 2009)

Thanks so much Bob. I've been so curious about casting and you've really answered a lot of my questions. Thanks for sharing!


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## MBrennan (Sep 22, 2008)

Awesome Tutorial! I too have been wanting to try this.

Did you have to make a slit in the rubber mold to get the skull out, or is the rubber flexible enough to remove it without tearing.

Thanks again for taking the time to post this.


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## Joiseygal (Sep 3, 2008)

Great Tutorial Bob. I don't think I will be doing this anytime soon because of the cost, but sometime in the future I would love to give this a try.


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## BobC (Aug 23, 2005)

MBrennan said:


> Awesome Tutorial! I too have been wanting to try this.
> 
> Did you have to make a slit in the rubber mold to get the skull out, or is the rubber flexible enough to remove it without tearing.
> 
> Thanks again for taking the time to post this.


Yeah the Rubber is flexible enough to remove without tearing or slicing. :jol:


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## scabbie (May 15, 2010)

BobC,This is an awesome "How-To!"You did a great job.I plan on trying my own mold in the near future.Thank you! Scabbie.


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## BobC (Aug 23, 2005)

Thanks, I'm working on my new skull mold this weekend this one will be in two pieces with a detachable jaw. I will either post the new pics onto this thread or start a new one. :jol:


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## BobC (Aug 23, 2005)

Thought I would dust this How-to off been in the basement for awhile. I will be adding my seperate jaw version after Halloween.


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## doggieshop (Jul 15, 2008)

Awesome Tutorial! Thanks


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## pennywise (Aug 5, 2008)

This is great! I can't afford all the materials this year, but it's good to keep in mind when I do get a chance to try it out. Thanks.


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## niblique71 (Dec 2, 2009)

Can we PLEASE Do this at an upcomming MnT?? I'm Dying to have the ability to cast 100 skulls (or other objects) for just a few bucks each. Thanks again for this Bob.


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## BobC (Aug 23, 2005)

Greg, sure we can do this as a project....smooth on is actually like a half hour away from you in Easton PA I believe. It takes a few day to complete but I am sure what ever we dont finish can easily be done on your own.


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## Lilly (Jun 13, 2006)

Nice skull..Great How to Bob..


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## [email protected] (Aug 25, 2012)

This looks like a great project. I just wish it wasn't so cost-prohibitive. I can't think of anything that I could mass produce that would ultimately justify the startup cost. Grrrrr.


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