Cast Latex Backbone and a Scorpion SFX Design.

This will be my final Instructable on using liquid latex for costume design. For two part mould casting I tend to use gelatin ..... but that's another 'ible.

We are going to look at casting raw latex without baking or foaming, and run through the design for a Scorpion Queen commission.

This is the working drawing for the scorpion, I just painted over a photo off the net for the basic structures. I also had a design for a costume of eerie fingers. The scorpion does not require casting, but the fingers will. I actually got to do the scorpion shoot, but got made redundant before we completed the fingers shoot, so that costume is sitting in my workshop waiting for a victim and a studio. If I get it finished I'll post a comment with a link to it.

Materials list for this instructable:

Theatrical Liquid Latex
Hot melt glue
Plasticene
Plaster of Paris or Dental Casting Plaster
Pipe Lagging sponge
General purpose glue
Acrylic Artists Paint and Ink
Wax Paper
Cotton Wool

Imagination

Here's an aside.

To make quick veins, lay three layers of latex down on a bit of wax or greaseproof paper. Let each one dry before you add the next.
Trail some hot melt glue over the latex, make sure the glue trails to a point.
Paint the hot melt red using acrylic paint.

Add three layers of latex over the glue .... hey presto, instant veins.

OK, some designs need to be sculpted and cast. If it is a complex design that must fit the wearer, then the method here is no good. For that you would need a two part mould and a different technique.

However, we can still produce good results for a generic type of casting. Single mould casting.
The proper clay to use for this is called 'Plastilene', an oil based modelling clay that won't dry. But it is expensive and has to be ordered. Forget that and go and get some oil based kids modelling clay called 'Plasticine'. Virtually every kid has used this at some time.

To make fingers or hands is easy, just roll out some sausages of clay, plonk them down on a smooth non-porous surface and then prod them around with some implements to make wrinkles and what not. I used some small cones of clay to form talons. Smooth down the edges to prevent massive undercuts.

Now build a 'fence' of clay round your sculpted fingers or hand. It needs to be at least 25mm (1 inch) from each side and 25mm (1 inch) higher than the highest point of your model. The fence in this image needs to be a bit higher. Make sure that the fence is sealed or the plaster will run out underneath it.

Keep it simple when you first try. This mould pattern took me 30 seconds to knock up as I write this because I didn't have a picture of this stage.

Mix the plaster 2 parts powder to 1 part water (forget all the fancy formulae) this mix will work. Carefully pour the plaster into one corner of the mould trying to avoid air bubbles forming.

Fill the mould. Wait about 15 minutes and you should be able to de-mould. Do this by carefully pulling away the fence first, then gently try to lift the plaster off the board.
Turn it over and pull out the plasticine, if it won't all come out, leave it at this stage because the plaster is still very soft.

Leave it overnight to dry. Then use tweezers or some other tools to carefully and gently remove all traces of the plasticine. Don't worry too much if the sharp edges of the plaster mould break up a little, it won't really cause too many problems.

Once the plaster has dried, dust it with a little talc using a blusher brush, then put a coat of latex into all parts of the mould and allow say 5 or 6mm to come onto the top. here's a hand mould with the first layer of latex added.

Once each layer of latex has dried add another until you have 4 or 5 layers.

Let this dry thoroughly then dust all over with plenty of talc. carefully lift one edge and peel out the latex cast, dusting both sides with talc as you go.

You will end up with a floppy latex cast.

Here's the hand, along with an image of one of the finger sets that I am going to use.

The fingers are far too floppy to be of much use as they are. They need to be added to a base. You could cast a single piece and make a single base, but I am casting quite a few and adding them to a backbone.

I have carved a tail out of pipe lagging, then laid down a base on wax paper for the backbone. Here you can see the second of three layers of latex being painted on. Each layer should be left to dry before adding the next.

Once the latex has dried, (I have added 4 layers of latex to the tail), use some cotton wool to fill the backs of the finger casts. Don't try and over fill them, just enough to hold the shape.

By pressing dry latex onto dry latex you get an instant bond. Once stuck into place simply run a fillet of latex round the edges to get a good seal.

Add all the ribs and the tail, then start to fill out the spinal column with cotton and latex.

You should end up with a full backbone of cast bits.

Here are a set of cast hands which will be used as part of the costume. They were made exactly the same way.

Next the latex needs painting. In this case I didn't add the paint to the latex because I wouldn't be able to see the effect in the moulds.

Instead, the 'rougher' texture of the cast latex will hold make up or acrylic paint. Use whatever colours you like but remember to add shadows and highlights to create some depth.

Here's the finished ensemble, painted and ready for some poor naked girl to have it all glued on.

The hands will go across her front, the back bone down her back (obviously). There may be some horns and a green body paint.

I started with the tail. This was going to be interesting!

I used 2 1/2 inch pipe lagging and cut sections at angles with a bread knife.
These were then organised and arranged for a pleasing shape and glued together using general purpose glue.

Once all the sections were glued together I added some cotton wool to bulk up the stinger, then profiled the sections with a sharp knife the Dremel and sandpaper.

Then 6 coats of latex.

The tail had some more cotton wool added, some yellow colour added and a backplate made up of scales using the standard process. I used cotton wool sheets to create the scales.

The tail was then glued on and the joint strengthened up.

The tail and back were painted using acrylic paint and ink and a set of pincers carved from lagging and painted with a single scale mounting plate.

The costume was glued on using latex and dusted over with talc. Then we painted her from head to foot.

The end result looked like this. These are the least revealing shots I could find.

More can be found here:

Marshon