Noobie's crack at sculpt and cast-Many questions, advice appreciated

Wow! Allow me to edit...no more copy and paste for me..sorry about that folks

Your pics are pretty small, so it's hard to tell much from it. That said, bravo for diving in head first and congratulations and a promising start.

Sculpey is a perfectly fine materail to sculpt in, but it is not self-supporting at all. This is why it is cracking and falling apart on you. It's not the dryness of the clay, but rather its own weight pulling against itself that is your problem.

Simply put, you need an armature underneath to support the clay. Even a cheap styrofoam wig head would do the trick and those can be found cheaply on Ebay or any hairdresser's supply store.

Also, you are correct that you don't need to bake the Sculpey if you are going to mold it.

As for molding and casting... The kit you bought should contain plenty of material for doing a mold for that piece. I do helmet molds frequently and can typically do 2 helmet molds from a kit that size. You should even be able to get about 3 or 4 helmets from the resin.

I've found that the 2 oz Dixie drink cups found in any supermarket make the perfect measuring tools for doing helmets. Fill 1 cup each with part A and B of the silicone and then mix together in a larger cup and then apply. Let that set and repeat 3 or 4 more times until you've built up the appropriate thickness. After the last layer has set, build your mother mold with the plasti paste and you are done with the mold.

The same cups work perfectly for measuring out the resin for casting as well. Three to 4 layers seems to give the best balance between strength and weight. I would however recommend getting a sample kit of Onyx Fast from Smooth-On, as it makes for better helmet shells since it is better suited to slush casting.

Oz

Forgot to mention, but very important. Do not use latex gloves or anything made of latex on this project. In fact, don't let latex anywhere near it. Platinum silicones will not cure if it even smells latex in the room.

Check out the Polytek range of silicone and molding products. I use their Platsil Gel silicone and they are good at coping with latex being in the room. Polytek Development Corp.-Polyurethane & silicone mold materials and casting plastics for making rubber molds to cast concrete, plaster, wax, resins & foam from Polytek Corp.

I use them under the Mouldlife brand.

You want the Onyx Fast. It sets in about 3 minutes. One of the $20 sample kits will do just fine.

One other note on the silicone. Get you some disposable chip brushes from Harbor Freight or the like and dab the silicone to pop the bubbles.

So I was watching the how-too video that came with this kit and the guy used clay shims to seperate the support shell into three pieces...I was palnning on doing two straight in half like I usually see but...does it have to be modeling clay used to seperate it? Seems like a lot is needed.

FYI, the support shell is called a "Mother Mold", and the silicone is called the "Daughter Mold". Don't want the jargon to confuse you.

And no, you can use anything to build a separating wall for the mother mold. To save time and clay, I will often make a divider from a thin piece of MDF, or even foam board. Just cut a hole in the middle that fits your mold and fit it over the center. You can then use a small amount of clay to secure it in place and fill in the gaps.

BTW, this is also where you will want to use the Sonite Wax. It will keep the shell material from sticking to the dividing wall, and then to itself when you lay up the other side.

Sorry for the double post but just as an update here's some slightly more finished (and better quality) pics...sorry for the darkness- room doesn't get much light. As for the design, it being my own I think only I will really appreciate it XD (I know it's kinda funky but a story goes with everything). It's a good size...about 28 inches around...oh and I'm not a dog murderer....You can find all sorts of things on etsy.

since you are doing a silicone mold, single piece sleeve I'm assuming, you need to be VERY careful with that scull the silicone will lock in those holes between the nose and the inside of the mouth, which could potentially rip a section out of the mold. best bet would be to stuff clay under the skull and incorporate the fill to your sculpt.

The silicone will flow into every nook and cranny, be very aware of this and seal off any areas that may be surrounded in silicone, you can always cut them out later once its cast. also if its a real skull you need to seal any sinus's or holes in the skull, or else the silicone may use those holes to fill the skull and lock that entire portion.

Filll the nose! Got it! Thanks, good thing you told me, I filled in the back and most of the eye cavity but totally forgot about the sinus!

Sand the thin areas with some rough sandpaper (80 grit or similar) and the SC 300 should bond to it okay. It would also help if you thickened it up with some kind of filler.

I use Urefil 3 as a thickener all the time, but plain old sand or talc will also work. To make a spreadable paste it usually takes about equal parts filler and resin.

then smooth cast it shall be! Thanks- now to get some sand...

Congatulations.

Just powder the mold with talc before casting and it should come out fine. And remember, best to use 3 or 4 thin layers than trying to 1 thick one.

Came out gorgeous!...well except the one huge ass dent in the side- but I'm thrilled! the detail in the skull (which was totally destroyed in the process) is amazing! Hoping I can maybe heat gun the thing out as it'll be a little while before I can cast another. Here's my boyfriend holding 'er up.