Prosthetic Sculpting Basics

I wrote this as an intended post originally, then decided to do a series of videos based on it instead (Part 1 – Blocking out, Part 2 – Refining, Part 3 – Skin texture ), so consider this post a summary of the tutorials.  Reading and watching the information helps retain it and also can be printed out as a handy guide.

Sculpting is one of the most creative aspects of  prosthetics and is fun to do.  The best thing is that to practice, all you need is a cast to work on and something to sculpt with.  You don’t need to mould everything you sculpt…just sculpt something, photograph it and then reuse the materials.

This is an economical way of learning, as well as building up a portfolio of sculpts which you can review later and seek advice without cluttering up your home with dozens of delicate sculptures.

For the purposes of this post, I am assuming all sculpting will use plastiline rather than a water based clay.  This is simply because plastilines are oil based sculpting mediums which do not dry or shrink like water based clays, and achieve a greater level of detail.  Lighter fluid (naphtha – the kind used in Zippo lighters) is usually the solvent used if any as this is relatively easily sourced and stored in a workshop or tool box.

1. Reference
If possible, use reference which is as close to the look you want first and use this to inform your sculpt.  Getting a general feel for what you want before you pick up any clay is usually time well spent.  It will get your juices flowing and inform your brain as to what shapes you should be looking at.  The more you look, the more you will see.

2. Design
If you are creating a sculpture that uses wrinkles or another sculptural device (horns, warts, scales etc), it pays to vary them in intensity and regularity.  If they are too similar and all over the sculpt, they will have less impact than a few good, well placed ones.

3. Sketch out boundaries and detail
I like to use a pencil to mark out where the sculpture need to finish, such as around hairlines, ears and lips etc.  This gives you a specific point at which the plastiline is going to stop and real skin will begin.

Also, if you intend to keep any of the original wrinkles and folds of the skin in the sculpt, it helps to mark these out too.

4. Block out
Start by putting small blobs of plastiline onto the surface and be sure to press them firmly to the surface and making them flat.  It is usually a good idea to keep a minimum thickness of 2-3mm and flattening the blobs like this as you go will ensure that this thickness is maintained.  You can always carve in or add more later.

Work sausage-shaped blobs around any main wrinkles, folds and lines you wished to keep so that as you build up over the surface you do not obscure their position.  Blend these blobs together – except those you wish to keep as wrinkles in the final sculpt – using a small tool or your fingers.  These lines can be left intact and worked on later.

Often it is desirable to retain the position of the original wrinkle in the skin underneath as this is the natural place for the skin to compress.  Doing so will ensure that the appliance folds in the same way and works with the skin better, creating more natural movement.

Build up the larger forms and establish the gross, overall shape or ‘form’.  It does not need to be particularly neat at this stage – we are concerned now only with the rough shape and form.

5. Refine techniques
Once the bulk of the shape is there, it is time to refine the form and surface.  For this, I like to use serrated tools such as a griffon hook or loop tool.

These loop tools comes in many different forms and can be bought although many sculptors make their own using piano wire, guitar string or fret saw blades. (click here for my tutorial on making your own loop tools).

The surface can now be gradually shaved to a more organic, coherent form which appears to flow gradually from one form to the next.  This essentially is what all appliance sculpting is – placing blobs of material in the right place and blending them together so they look like one, continuous surface.

The serrated tools work best as they gradually shave small amounts of material without drastic scoops being hacked away.  By varying the pressure, you can shave down the edges to a natural taper, so they arrive at the skin at an angle which does not suddenly shift from one to the other.

As you refine, you can reduce the pressure to make finer and finer tool marks. I also recommend working the tool in one direction, and then across it the other way to ‘cross-hatch’ the marks.  These finer tool marks can be smoothed out with the thumb as the amount of material you are moving around becomes less and less.

Surface rakes made from piano wire & brass tubing

Using a surface rake of some kind to gently score tiny scratches in to the surface will help smooth out the finish in a very natural looking way.  The tiny lines need not be deep as you use use minimal pressure – the effect comes from multiple passes which gradually smooth out the surface.  The long prongs act like a kind of suspension, rising and falling with the undulations of the surface, so the scratches are not deep.

6. Texture techniques
Good texturing is of course important, but should not begin until the form is correct – think of it as putting really good wallpaper on wobbly walls.  You need to get the surface right first, then tinker away with the pretty texture afterwards.

What is the difference between ‘form’ and ‘texture’?  Well, if you were to manually focus a camera on the final sculpt so that the image you saw was slightly blurry then what you are looking at is the form.  Focusing  the image until it is pin-sharp will then reveal the texture.

What the final texture is to be is down to you and your  design, but commonly required textures include skin pores, wrinkles and other fleshy, non-descript textures.

Using a small, reticulated foam sponge (commonly known as a black ‘stipple’ sponge or scott foam) through thin plastic film such as sandwich wrap works well.  It creates a good non-specific skin texture quickly.

Tooling (literally, gently creating texture by using sculpting tools directly) through plastic of varying thicknesses can create good little wrinkles, folds and pores.  Usually use thin bladed tools, small loop tools or even pins for this.

Use this as a rule-of-thumb guide, but really nothing will beat just getting stuck in – grab some plastiline and get your hands dirty.  Reading about sculpting will inform you, but enjoying putting it into practice is the only way to actively see any improvement in your ability to actually do it.

If you would like some feedback on your sculpts or just want to share what you have done, please feel free to get in touch.  Let me know what you think and leave me a comment below!

Happy sculpting!
-Stuart

All material, images and text © Stuart Bray 2011