I had read on the Hauntforum discussion boards a post about making silicone molds to cast paper clay items in. The process was lifted from Instructables, a website that contains some interesting Halloween-related projects (and a lot of dreck too).
|The mold ingredients|
|The rubber masks|
In his original post, MacabreRob discusses how mixing the caulk with corn starch is a little difficult because of the stickiness of the caulk, but after awhile it yields up and depending on how much corn starch you use you'll have between a few minutes and hours to work with the mixture. At a 1:1 ratio of caulk to corn starch, it you just a few minutes; at 5:1, you have 2 hours.
|Pressing mask into Oogoo|
So I squeezed out about half a regular size tube of silicone into a plastic container and eyeballed about a quarter of the amount of naphtha. I put the lid on the container and shook it vigorous back and forth and it obtained a much more liquid consistency. I mixed it with a bit of corn starch (I figure it was about one quarter the amount of caulk) and using a popsicle stick mixed it all together until smooth and flattened the surface.
|The resulting mold|
I had intended to use paper clay, but really didn't feel like mixing up a batch, so I used plaster instead. I mixed up a batch and poured it into the mold, which had only been setting for about a half hour total. I left them in there for an hour or so and pulled one out and found the plaster was still wet. Maybe because of the silicone it stays wet longer than otherwise. While it gave the face an interesting texture, I decided to let the other head cure overnight.
|The mold pops out easily|
Since I didn't take photos of the process, I did it tonight and noticed the plastic packaging of the rubber skulls has their reverse image molded into the plastic. So I just poured another casting of the faces, but this time using the packaging. I want to see if they cure faster than the silicone mold ones did. I'll report back my findings.
The other mini project I did was used Great Stuff expanding foam to make a brain. I saw Steve from Steve's Haunted Yard (Yardhaunter5 on YouTube) do this and it seemed like a quick and easy project. And it was! Using a plastic Jell-O brain mold, I filled it about half way up and let it set over night.
Unfortunately, the results were disastrous. Although the outer portion dried to a hard shell like Great Stuff does, the inner portion -- the part that would have the brain design on it -- didn't dry, even after 24 hrs. When I pried the "brain" out of the mold. it split in two revealing a still damp interior. Now here it is two days later and the part that I left in the brain mold is still damp in parts, though mostly cured. I'll have to go back and review Steve's project to see what I did wrong.
With a Make & Take group meeting yesterday (Talking Boris Skull hack) and another scheduled for next Saturday (Coffin Creep, but we'll be working on the lid mechanism) it's great to be back in the swing of things building props!