[GOT]

I have just recently engaged in the world of latex mold making and could use any advice people have. My first mold is a cast of a skull using "Mold Builder" and I have quickly realised that this mold is going to take about 3 weeks to make (20 layers of latex and it is taking about 24 hours for a layer to dry, even when using a hair drier). Am I missing something here? I bought some polyurethan foam from artstuf.com and I think I have a good plan for making foam skulls but I hate to spend 3 weeks and $40 to screw up. Any advice from the masters?

 

[Sickie Ickie]

Vlad and DS both have great advice on this. Do a search for similar threads and a ton of stuff will pop up.

 

[turtle2778]

wow 24 hours per layer? How much are you putting on??? I was able to do three in roughly 8 hours. They werent super thick, but thick enough i thought. I was figuring 3 a day for a week should do it.

 

[Richie]

Go with several layers of the latex for the outer skin and fill the balance with foam. Don't forget to install a piece of 1" or larger PVC pipe into the skull. This will allow you to connect it to a body later.

 

[playfx]

Instead of latex what about using silicone caulking? you can mix it with a few drops of acrylic craft paint, brush it on and it will set up in 15-20 min.

 

[dave the dead]

wow 24 hours per layer? How much are you putting on??? I was able to do three in roughly 8 hours. They werent super thick, but thick enough i thought. I was figuring 3 a day for a week should do it.

yeah...definitely! If you apply this stuff super thick, it does take a long time to dry....go with the thin layers and it will build up alot quicker for you. The end result will be the same, only much quicker......a strong and stretchy mold with good detail.

 

[GOT]

Thanks for the help, guys. I was planing on doing the foam thing but I don't want to rip the mold when I pull it off so I am making it thick (but after 5 thick layers, it still looks less than 1/8th inch thick). I will persevere and let you know how it turns out..

 

[jrzmac]

this guy used cheese cloth in between layers of the latex. to build it up more and make it stronger i guess. may make it dry a bit faster also?
http://wolfstone.halloweenhost.com/Casting/cstskl_CastPlasterSkulls.html

 

[Vlad]

Hi Got, I'm glad to hear that you're moving into mold making. Aside from skulls, you'll be amazed at the things you can copy. I'm afraid that you have a few misconceptions about the mold making process though.
The first problem seems to indeed be that you're applying the latex much too thickly. Apply thin layers, and don't wait until the layers are completely dry, they should still be "tacky" to the touch. After the first two thin layers of latex which are used to pick up the detail from the original, you should be using cheesecloth with latex for every other layer. Also, heat (in the form of the hair drier) is a prime killer of latex, it's use at any point around latex should be avoided.
A 16oz. container of mold making latex that I purchase from Michael's craft stores for about $7 using their 50% off coupons, is more than enough to make one heavy duty skull mold. $40 estimate for a skull mold is way out of line. Where have you been getting yours?
As far as worrying about tearing the mold when you remove it by making it thick, you're actually getting into a different problem. A thick one piece latex mold will be very difficult to get off at all. I usually cut a slit up the back of my skull molds to make removal easy, while still maintaining the thickness necessary to not have to use a mother mold. It leaves a small seem line that I have to trim off of each copy, but it's well worth it as far as easy removal goes.
Here are some small how tos on mold making that might help>>>>>>>>>>
http://terroronbeechwood.com/index.php?pr=How_To_pages
If you're going into making foam skulls with 2 part foam, here is what my latex skull molds look like for that particular process.>>>>>>>>>
Latex skull mold before removal from original>>>>>>>>
http://img.photobucket.com/albums/v194/TerrorOnBeechwood1/Linked/P1010002.jpg?t=1177452182
Latex skull mold after removal from original, with air holes, and pouring hole cut out>>>>>>>>>>
http://img.photobucket.com/albums/v194/TerrorOnBeechwood1/Linked/P1010008.jpg?t=1177452211
Skull mold taped back together with foam poured in, before copy is removed.>
http://img.photobucket.com/albums/v194/TerrorOnBeechwood1/Linked/P1010020.jpg?t=1177452236

 

[octoberist]

mold release

Encouraged by your posted pics, Vlad, I am planning to use 2 part foam to cast some skulls from a latex mold. Do I need to use some kind of mold release? Or does the cast foam piece come easily out of latex? Thanks.

 

[Uruk-Hai]

Great advice everyone. I've made latex molds before of rock faces (my other hobby is model railroading) but they are mostly flat so doing a more 360 degree mold is new to me. One question I had was what if you wanted to make a separate mold for the skull and jaw - would the process be the same? Would there be any additional difficulty due to undercuts. etc.? Has anyone done this? I'd like to have the 2 pieces separate as I think I could get more variety from the molds and give the finished skulls more of an individual look based on how you pose the jaw.

 

[GOT]

Well, after four attempts, I finally got a foam skull using a 2-part polyurethane foam. It would seem, however, that my mold stretched quite a bit despite my Great Stuff-in-a-box shell I made for it. A little discouraging. Any tips? Should I use plaster for the shell?