Making a Positive Paper Mache Mould Using Plasticine

People often ask me about my paper mache moulds, so here’s my updated approach for creating positive moulds that give you maximum flexibility and reusability. So … let’s get started!

Why Positive Moulds?

I use positive moulds—meaning the paper pulp or paper mache dries on the outside of the mould form. I tried negative moulds early on, but they never worked well for me because the paper mache doesn’t get enough airflow to dry properly when it’s inside a cavity.

Positive moulds might allow for less fine detail initially, but that’s actually perfect for my process. I’m after the basic underlying shape first, then I add the details later during the sculpting and finishing stages. This approach gives me more creative control over the final piece.

Positive moulds can be carved from wood, cast from gypsum, or sculpted from plasticine. Each material has its advantages, but I’ve found plasticine to be the most practical choice for my workflow.

Materials You’ll Need

For the armature:

• Recycled aluminium foil
• Cardboard scraps
• Masking tape
• Wire (20-22 gauge works well)

For the mould surface:

• Plasticine (oil-based modelling clay)

Tools:

• Wire cutters
• Scissors
• Sculpting tools (or improvise with kitchen utensils)

Why I Choose Plasticine Moulds

Plasticine has become my go-to material for several compelling reasons:

Reusability – Unlike plaster or wood moulds, plasticine can be completely recycled. When I’m done with a project, I simply warm the clay and reform it for the next mould. This makes it incredibly cost-effective over time.

Extended Working Time – Oil-based plasticine doesn’t dry out like water-based clays, so I can work on moulds over several sessions without worrying about the material hardening.

Precision and Detail – Plasticine can be smoothed to create seamless surfaces. It’s also easy to make adjustments—if I don’t like a curve or angle, I can simply reshape that section.

Material Economy – Pure plasticine moulds would require enormous amounts of clay for larger projects. By creating an internal armature first, I save substantial material while maintaining structural integrity.

Building the Armature Foundation

The key to an efficient plasticine mould is starting with a well-planned armature. Think of this as the skeleton that will support your sculpted surface.

Step 1: Plan Your Basic Shape Sketch your intended form from multiple angles. Consider the overall proportions and where you’ll need the most structural support.

Step 2: Create the Core Structure Start with crumpled aluminium foil to establish the rough volume. This lightweight core takes up space without adding unnecessary weight to your finished mould.

For more complex shapes, use cardboard to create flat planes and geometric elements. Cut template pieces that define key angles and curves, then tape them to your foil core.

Step 3: Add Wire Reinforcement Use wire to create structural elements that need to maintain their shape under the weight of wet paper mache. This is especially important for:

• Protruding elements (arms, noses, decorative features)
• Areas that will support significant clay weight
• Transition zones between different parts of the sculpture

Secure the wire to your foil and cardboard base using masking tape, ensuring all sharp ends are covered to protect both your hands and the plasticine layer.

Applying the Plasticine Surface

Warming the Clay Before application, warm your plasticine slightly—either by kneading it in your hands or placing it near a gentle heat source. Warm clay spreads more easily and bonds better to the armature.

Building Up the Surface Apply plasticine in thin, overlapping layers rather than trying to cover large areas with thick chunks. Start with the largest surfaces and work toward details.

Press firmly to ensure good adhesion to the armature, but avoid pressing so hard that you distort the underlying structure.

Refining the Shape Use sculpting tools to smooth transitions and refine curves. A simple palette knife or even a butter knife can be excellent for creating clean, flowing surfaces.

For organic shapes, use your fingers to blend seams and create natural-looking forms. The warmth of your hands helps keep the plasticine workable.

Finishes Once your mould surface is complete, dust it lightly with cornstarch or talcum powder.

Tips for Success

Plan for Removal – Consider how you’ll remove the dried paper mache from your mould. Avoid creating deep undercuts that would trap the finished piece.

Surface Texture – Smooth your plasticine surface thoroughly to prevent from sticking too aggressively to the plasticine

Multiple Sessions – One advantage of plasticine is that you can cover your work-in-progress with plastic wrap and return to it days later. The clay remains workable indefinitely.

Testing First – If you’re trying a new form or working at a larger scale than usual, consider making a small test mould first to work out any technical challenges.

Storage and Reuse

I keep mine in sealed plastic containers with notes about the clay’s condition and any additives I might have mixed in.

Well-maintained plasticine can be reused dozens of times, making this technique both economical and environmentally conscious.

What’s Next?

Once your mould is ready, you can apply your paper mache clay using the recipe I shared in my previous tutorial, or experiment with traditional paper strip methods. The beauty of having a reusable mould is that you can try different paper mache techniques and compare the results.

Thank you for reading! If you enjoyed this tutorial, you might want to check out my other tutorials.