Help with moulding and casting horses

[Laurielee]

I've been sculpting clay horses and other animals over the years just for fun. Needless to say they fall apart over time as the clay dries around the wire frame (they have high detail and various projections etc)

I'd love to know how to mould them properly, or slip cast them. I have searched this site but can't find info on moulding things with 4 legs, or multiple projections etc. although silicone seems to be the way to go. I also don't know what to cast them out of so that I can paint them - I'm thinking some sort of very tough plaster?

Any help would be greatly appreciated!

[fritchie]

The main idea in making a mold is to choose "divisions" or parts of the mold, where it can be separated and later put back together in the same shape, but so that each division, or each part of the mold, can be pulled off your original shape, and also later off the cast shape, without damage to the horse or to the mold.

In your case, you want at least one part of the mold, one division, for each side, including the outside half of each leg, that side of the body, head, tail, and so on. I'm assuming the legs are fairly straight, and that the horse is nor rearing and doesn't have its head turned dramatically, for simplicity. The section under the horse's belly probably can be done in one part, as a third section overall. The only problem with making the belly mold in one piece will be bending the mold so that it can be removed.

That's a tight area, with four legs and the horse's trunk almost surrounding it. That's the critical reason for having some sort of "rubber" or flexible mold inside the overall plaster or rigid resin outer mold. (If it's not clear, all molds when they are assembled have an inside, which is flexible, and an outside, which is rigid and which holds the flexible pieces together.)

Other than these thoughts when planning your mold, the process is fairly straightforward, and you should find the rest of the process elsewhere on this site. Options are many, and other people probably will chime in with suggestions

[larrymoo]

Hi Laurielee,

Choose a wax based clay which won't crack on your armature. It never dries out and shrinks. If you're doing moderate detail work I recommend that you choose NSP medium made by Chavant, or a comparable clay, which holds together pretty well. I believe it is stocked in New Zealand at Golding Handcrafts, in Wellington. Don't use sulpher based clay if you're going to make a silicone rubber mold because silicone won't work atop sulphurated clay.

Make your armature with aluminum wire, available though most sculpt supply houses and on the internet.

Most persons cast the legs separately from the body. To most easily do this, you may wish to fit each piece of aluminum wire that makes up the legs with a connector made of brass tubing. This connection, perhaps 3/8 inch diameter, and 3/4" long, fits like a sock over the end of the aluminum wires that form the armature for the legs and then is glued in place with epoxy. That is, to put four legs on the horse, you'll need four piece of aluminum wire, each with a tiny socket on the end to slip over wires protruding from the armature that makes up the horses body. This permits you to remove the legs at any time, without sawing though a metal wire and damaging the clay legs.

This procedure is clearly shown on a video made by sculptor John Brown which is available over the internet. He has several. His video that covers this topic best is on how to sculpt a maquette.

Here in the states, two companies among many others, offer silicone for mold making. I use Smooth-on and Polytek. Both have catalogs and extensive instructions on mold making. Information about their New Zealand dealerships (if they have any) will probably available on their web sites. You'll get far better information from their instruction manuals and literature than I offer in this note. In making this type of mold, I use brush-on silicone rubber, which most dealers of these materials have available.

Encapsulating these silicone rubber molds is a "mother mold." Most often made of casting plaster. I paint my rubber molds with a "Murphy's Oil" liquid soap before applying the plaster. I probably don't need to since silicone sticks to nothing but silicone, but I do anyway. Plaster making is covered well on the internet at several sites.

If your horse is small, perhaps 18" tall or less, you with probably want to pour your horse mold with a liquid resin to provide adequate strength, instead of a hard plaster. A variety of liquid resins are available. I use a white resin from smooth-on that sets up in less than five minutes. If you pour your horse with plaster, you'll probably wish to choose a strong grade, rather than regular casting plaster which is relatively weak (choose a white hydrocal for instance).

You'll may find great amounts of information from some of the sources I noted above by googling for their web sites.

Best of luck to you.

[le granfred]

I've been sculpting clay horses and other animals over the years just for fun. Needless to say they fall apart over time as the clay dries around the wire frame (they have high detail and various projections etc)

I'd love to know how to mould them properly, or slip cast them. I have searched this site but can't find info on moulding things with 4 legs, or multiple projections etc. although silicone seems to be the way to go. I also don't know what to cast them out of so that I can paint them - I'm thinking some sort of very tough plaster?

Any help would be greatly appreciated!

hello.

It depends on the size of your sculpture.
If I were faced with such a work, I would first make a replica out of your clay, with plaster.
Open the mould, clean it, dry it, and then saturate it with soap and a layer rape oil, before filling the mold with plaster or resin.
Then it is very easy to handle your work after destroying the mould, and do a beautiful mould with rubber cast under resin shell.

understand?