Noob, wanting to cast sculpture.

[DarkArt]

Hello guys and gals, I am looking for a little advice on how to make a mold and cast my sculpture.

I have no experience using anything like this so want to make sure that i have all the info before i take the plunge. Firstly this is the kit I am thinking of buying....www.mbfg.co.uk/category-186/7619.html. The sculpture I want to cast measures 18" high 12" length and 6" from back to front, and is made from oil based clay. ( it is a bust with open mouth)
I have some pictures but do not know how to upload onto this site.

Is the kit I am thinking of buying what I need?
Do I need a degassing chamber?
How much of what will I need for a cast this size?

[Fleafa]

Such a sculpture would probably require slush-casting or rotational casting. Otherwise, you would use an awful lot of resin and likely end up with trapped air pockets.
The kit you list, whilst a decent intro kit for conventional casting, is not ideal for this process.

[RageofAchilles]

for ease of use you need a condensation cure silicone that can be thickened with a thixo agent.
Lots of it too. Tomps do a budget condensation cure that can be thickened

http://www.tomps.com/rtv-silicone-rubbe ... p-450.html

[DarkArt]

[mangozac]

It's quite ambitious for a first project!

Polyurethane resin is what you want - it will facilitate slush casting as Fleafa has suggested.

[DarkArt]

Yes i realise that it is a very ambitious for a first timer, Do you think it will pose many problems?
What size tubs would be needed for a project this size?
Many thanks for the responses.

[RageofAchilles]

If you get the Thixo agent you can spread it on with a spatula or other tool. This is a really good idea if you have a lot of undercuts as you can place the silicone where you want it to any thickness.

condensation cure does not suffer from cure inhibition, that can be caused if you use the wrong clay or wear rubber gloves while handling addition cure silicones.

There are tutorials all over the place for making moulds for this type of project, there are several approaches to it. It's going to be a case of what you think you will be comfortable with on your first outing.

when you come to casting you basically want to create a skin, by sloshing or painting the resin in the mould. when that is done you can use a filler additive to the resin to fill up the void. This saves money and cuts down on heat produced by such a large mass of resin. Or leave it hollow...

Here is one approach shown by Smooth-on, obviously showing their products :

https://www.youtube.com/watch?v=sOyBawt1-Ec

if you like the look of the Smooth-On approach , you can buy their products in the UK from this company
http://www.benam.co.uk/

They are very helpful and approachable guys at benam, they went the extra mile to help me out once, so I can't praise them enough.

I think you can see that it will not be simple or cheap to do want you want to do, but it is worth it
Good Luck!