Introduction: How to Sculpt Chocolate

About: Artist in Residence at Pier 9, currently exploring a vast array of new tools with which to injure myself.

How to make chocolate sculptures on a budget

Most store-bought Easter eggs are disappointingly bland in design. Even the fanciest high-end chocolate eggs tend to be cast in a simple design with, if you're lucky, a few swirls of caramel or chocolate drizzled artistically across the top. Given the limitations of mass production this is understandable, but there's no reason why extremely detailed and creative chocolate sculptures can't be produced on a smaller scale.

Slightly late for Easter, this Instructable will show you how to make your very own overly-elaborate chocolate sculptures, using this newly hatched chick and egg as an example. Very little skill is required and the only specialist material needed is cheaply available from most good plumbing or DIY retailers.

While some of the details of this project are specific to this bird sculpture, all of the principles can be adapted and applied to sculpting whatever you want from chocolate.

Step 1: What You'll Need

Relatively few materials are needed for this project, but make sure that you select them carefully (see the warnings below).
  • Modelling clay (plasticine) - make sure that this is non-toxic. You'll need enough to sculpt an original model of whatever you've decided to make.
  • Food grade silicone - also make sure that this is non-toxic. Various types of silicone available on the market are advertised as "food safe". Some of these are designed specifically for the purpose of making moulds and tend to be extremely expensive, but also hard-wearing and capable of capturing incredibly fine details. These often come as two-part resins.Other types are not designed for this purpose at all, but are instead intended to be used as sealants in kitchen areas, on surfaces which may come into contact with food. One of these types of food grade silicone comes in a cylindrical cartridge and does not need to be mixed before use. This is the type we are going to use. Because it is intended for such an unglamorous purpose, it is extremely cheap. It should still be entirely safe to use, since we are only using it as a cooling surface for the chocolate.
  • A non-toxic release agent, such as cooking oil - this is to prevent the plasticine sticking to the silicone. Cooking oil is ideal, and often comes available in a spray.
  • Plaster of Paris - ideally already impregnated into gauze (also known as modroc), but you can do this step yourself. Be careful if you have a known plaster allergy.
  • Lots of chocolate! How much you need will depend on your sculpture, as will your choice of colour(s). Make sure you choose high-quality chocolate that is suitable for melting and cooking.
The following bits of kit will be needed:
  • Sculpting tools - you can get by with just a sharp knife, but it's nice to have a few differently shaped sticks, scoops, scrapers and picks for if you need them. Carving sets are available in most art shops, but you can usually get by with household implements such as spoons, pens, screwdrivers, lollipop sticks, etc.
  • Sealant gun - make sure this fits whatever size of silicone cartridge you use
  • Craft knife
  • Double boiler or bain-marie
  • Mixing bowls
  • Refrigerator
An important warning about plasticine and silicone:

Different types of modelling clay contain different chemical compounds. Similarly, different forms of silicone sealant react in different ways. Sometimes unfortunate cross-reactions can occur which make a particular type of clay stick to a particular type of silicone. Needless to say, this is very frustrating when it happens mid-project.

Before you begin, be sure to test your materials together by covering a small amount of your modelling clay with silicone and letting it set. If they separate easily once the silicone has cured, then you're all set to carry on with the project. If they stick together and lots of modelling clay is left on the silicone, then find another type of clay (ideally one that does not contain sulphur) and try again.

Experiment a bit here. You might find that a thin layer of release agent (i.e. oil) between the clay and the silicone solves this problem, or you might find that no release agent is needed at all. I can't stress strongly enough how useful it is to test this before you start the rest of the project.

In the test run for this project, I accidentally used the wrong sort of modelling clay and had to spend hours scrubbing a thin layer of plasticine off all of my moulds. Prevention is definitely better than the cure*.

*Ho ho.

Step 2: Sculpt the Egg

Read all of that stuff on the previous page? Chosen and tested all of your materials carefully? Then let's crack on!

Start by rolling up a fist-sized ball of newspaper and covering it in masking tape. This will provide the structure for the core of your egg, so you'll only need to cover it with a surface layer of plasticine. If you happen to have enough plasticine to make a solid egg, then feel free to try that. Just be careful not to drop it on anyone.

Coat the newspaper core with plasticine and roll it into an egg shape on a smooth, flat surface.

Use a craft knife to cut away a jagged edge to make the shell's opening.

Step 3: Sculpt the Chick

For the chick, it helps to use another colour of plasticine. This will allow you to distinguish it from the eggshell while you're still sculpting.

The chick's head starts off as a ball of plasticine slightly larger than a golf ball. Make two dents for the eye sockets, pushing upwards to create the arch of the eyebrows. Pinch together a rough beak with your hands, then refine it with a knife or another sculpting tool. A handy hint from my own experience: An upturned beak looks cute on a baby chick; a downturned beak makes it look like a conniving carrion bird.

Use the knife again to add definition to the eyes. The bigger and rounder you make them, the cuddlier your creature will look.

With a pen lid or a rounded sculpting tool, carefully add feathers to the bird row by row. This takes a while, but it's extremely easy work.

Step 4: Make a Nest

For the nest, roll out several dozen thin cylinders of plasticine and chop them into short (~5cm) lengths. Haphazardly weave these together into a rough torus, then press them all together so that there aren't too many large gaps. Remember that if your sculpture is too convoluted it will be impossible to mould.

Carefully place the egg and chick in the nest and put in a few more details. Here I've added cracks to the shell and scattered a few fragments of shell on top of the nest.

Spend some time giving attention to the surface texture of your sculpture. The advantage of the feathery chick is that it can still look good while not being entirely smooth. The egg, however, needs to be as smooth as possible if you want to make it look glossy and delicious when it is cast in chocolate.

Step 5: Cover Everything With Silicone

When you're happy with your plasticine sculpture, you're going to have to cover it with silicone to make a negative mould. This will almost certainly destroy your sculpture and, quite possibly, a little bit of your spirit. Fear not: while your original sculpture will soon be no more, its chocolatey progeny will live on indefinitely.

You'll want your plasticine to be as firm as possible before you start coating it, so it might help to chill it in the refrigerator for a short while before you go any further. Done that? Super.

I chose to separate the nest from the egg and cast it separately. If you've decided to use a release agent for the moulding step (see Step 1 - What you'll need), apply it now. Carefully brush or spray a thin layer of cooking oil onto the plasticine, being sure to work it into all the nooks and crannies.

Next, extrude your food grade silicone onto the sculpture. Cover a small patch (e.g. 5cm square) at a time, then use a blunt knife to smooth the silicone down and ensure it covers all of the surfaces. Any air bubbles that sneak in now will turn into unsightly chocolate warts on the finished product. Build up a layer no more than 0.5cm thick all over the sculpture (any thicker than this and the mould will lose the flexibility that will allow you to remove the chocolate from it without cracking).

Don't worry too much about how rough and messy the outer surface of the silicone appears; the important thing is that the inside has good, continuous contact with your sculpture (or at least with the thin layer of release agent clinging to the sculpture).

You should end up with something looking like a penguin encased in meringue. Hmm, that gives me an idea for another delicious cookery project...

Leave the silicone in a well-ventilated place for around 24 hours to allow it to fully set. During this period, it will reek of vinegar as acetic acid is released by the curing process.

Step 6: Mummify Your Chick

Make sure the silicone is completely cured before you move on to this step.

Because the silicone mould you're making is so thin and flexible, you'll need to reinforce it with a layer of something more rigid before you can fill it with chocolate. Bandages impregnated with plaster of Paris are ideal for making a thin outer shell around the silicone. You can either buy these ready-prepared (it's also known as modroc) or make them yourself by soaking gauze in wet plaster.

It is best to wear gloves when handling plaster, especially if you have sensitive skin or a known plaster allergy.

Wet the plastered bandages, drip off any excess water and wrap them around your silicone-encased sculpture. Your meringue penguin should now turn into a mummified penguin. Leave the plaster until it has set and cooled (plaster heats up as it cures - this may take between 30 minutes and 2 hours).

Step 7: Remove the Plasticine From the Moulds

Turn over the nest to expose its open base and pull out all of the plasticine. Carefully winkle out all the little bits that will try to cling on or hide in tiny cracks. If any large chunks seems really stuck, it might be a good idea to trim some of mould away so that the same doesn't happen with the chocolate later. Give the mould a thorough wash under hot, soapy water.

You can see here that I failed to use a proper release agent, so was left with a heavily stained mould. This required hours of painstaking scrubbing with an old toothbrush to clean fully. Don't make the same mistake: check that your plasticine and release agent are compatible with your silicone before you start the project.

Step 8: Crack Open Your Mummy

Use a craft knife to cut the plaster shell in two down the midline. Hopefully you will have chosen a shape that divides conveniently into two halves.

Don't worry about also cutting the silicone while you do this. You're going to cut the silicone along the same midline anyway, so just cut in one deep continuous motion and you should neatly cut through both the plaster and the silicone (and also slightly into the plasticine).

Step 9: Peel the Silicone Off

Having divided the silicone into two halves, peel it off the plasticine sculpture. Be careful not to stretch it too far or it might tear. Give the silicone a good scrubbing under hot, soapy water.

Again, notice the heavy staining on my silicone moulds. Do not make this mistake. Test your materials before you start. Grrr.

Step 10: Admire Your Moulds

You should now be left with:
  • A slightly battered plasticine sculpture
  • A set of silicone moulds
  • A set of matching plaster shells

Step 11: Melt and Temper Your Chocolate

At last, you can play with chocolate.

In a double boiler or a bain-marie, melt down and temper whatever types of chocolate you want to use. I recommend reading this excellent Instructable on how to temper chocolate by the inimitable scoochmaroo.

For my chick, I decided that I wanted the following different types of chocolate:
  • Dark (plain) chocolate for the nest and the pupils of the eyes
  • White chocolate for the whites of the eyes
  • Milk chocolate for the beak
  • Slightly off-white chocolate for the feathers
  • Marbled milk and white chocolate for the eggshell
This meant thinking carefully about the order in which I melted and mixed my three kinds of chocolate (plain, milk and white) before pouring them into the moulds. How you melt yours will depend on what colour scheme you choose.

Step 12: Fill the Moulds

Take your scrupulously cleaned and dried moulds, place them inside their plaster shells and chill them in the refrigerator for 10 minutes. This will encourage the chocolate to begin setting as soon as it is poured into the moulds.

Fill in the details of your moulds colour by colour, starting with the outermost layers. I began with the whites of the eyes, then moved on to the feathers, then the eggshell. Apply each layer carefully with a teaspoon and leave it to set (this can be hurried along by chilling) between layers. Don't worry if you spill a bit over the edge of any layer; simply let it cool then use a toothpick to scrape away the excess chocolate.

Once you have covered the entire mould and let it set, apply another layer of chocolate to the inside. Use the back of a spoon to spread this layer all the way up the edges so that the seams of the mould aren't too thin. Ideally, repeat this two or three times, cooling in between. If the chocolate is wafer-thin at the edges of the mould it will just crack when you try to remove it, so it's well worth getting this stage right.

Step 13: Hatch Your Chick

When you're feeling brave, gently peel the silicone moulds off their new chocolate centres. Try to do this when the chocolate is cool enough not to bend and warp, but not so frozen that it sticks to the moulds and cracks when you try to separate them.

Trim away any excess chocolate and assemble the two halves of your chocolate sculpture by warming their edges and pushing them softly together.

You may find that they no longer align perfectly due to slight deformation of the silicone moulds. This is not a problem: simply align them as closely as possible, then trim away any protrusions that are stopping them sitting flush together. If necessary, soften some more chocolate and use it to plaster over any cracks or gaps. For small cracks, heat the back of a teaspoon and use it to smear the edges together.

You can see where I've had to use some milk chocolate to fill a hole in the front of my eggshell. This left it looking rather grubby, so I added some more white chocolate on top for the finished sculpture. You can see in the next step that the front of the shell is noticeably less smooth than the rest as a result.

Another finishing touch was to apply the pupils of the eyes by dripping plain chocolate onto the sculpture from the end of a toothpick.

Step 14: Serve

Present your sculpture to a loved one as a gift, or keep it to yourself and eat it when nobody's looking.

Either way, enjoy!

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