What You’ll Need

• “Pure Mould” – Translucent Liquid Silicone Rubber for Mould Making – for detailed transparent moulds; excellent for observing the casting process
• “Liquid Mould” – Casting Liquid Silicone Rubber, 5-40 Shores, Bi-Component A+B – ideal for intricate shapes and small-scale objects
• “Liquid Mould” – Casting Liquid Silicone Rubber, 15 Shores 20.8 kg – suitable for detailed moulds and multiple reproductions
• “I–Gum” – Non-Toxic Silicone Putty for Mould Making – easy for quick impressions and non-toxic applications without gloves
• Mould box or container for holding the silicone and item to replicate
• Mixing cups, spatulas, digital scale
• (Optional) Release agent for demoulding
• (Optional) Gloves and apron for cleanliness

Essential Tools and Workspace Setup

Arrange all required materials before you start: silicone rubber, measuring tools, a clean mixing area and personal protective equipment. Good preparation ensures a smooth mould making process and minimises mistakes.

Step 1: Prepare the Model and Work Area

Begin by selecting the object you wish to duplicate (known as the “master”). Clean it thoroughly to remove dust or residue, which could affect mould detail. Place your item inside a mould box or container, ensuring a snug fit. If your object is porous or highly detailed, applying a thin layer of release agent can help achieve easy demoulding later. Arrange your materials and tools on a flat surface in a well-ventilated space to prevent accidental spills or contamination.

Step 2: Measure and Mix the Silicone Components

Accurate measuring is critical. Always measure the mixing ratio carefully to avoid curing issues. For liquid silicone rubbers such as “Pure Mould” and “Liquid Mould”, follow the manufacturer’s guidance — most require a 1:1 ratio by weight or specific catalyst addition. Pour the required amounts into a clean mixing cup. Mix slowly and consistently, scraping the sides and bottom, until the colour is uniform and free of streaks.

For quick impressions, “I–Gum” – Non-Toxic Silicone Putty for Mould Making offers a simple 1:1 hand mix, ideal for smaller objects and direct application without gloves, thanks to its non-toxic composition.

Avoid rapid stirring, which can introduce unwanted air bubbles inside your mould.

Step 3: Pour or Apply the Silicone Over Your Model

With the silicone thoroughly blended, gently pour it over your master in the mould box. For best results, pour from one corner and let the liquid flow naturally, filling crevices and details. This technique helps minimise air entrapment. Use a release agent when working with complex or porous items. If using silicone putty such as “I–Gum”, press and shape the mixed putty directly over the object, ensuring it captures every detail.

Tap the mould box lightly on the surface to help air bubbles escape. If possible, use a vacuum chamber or pressure pot to eliminate bubbles, especially for highly detailed work.

Step 4: Curing and Demoulding

Allow the silicone rubber to cure for the recommended time — typically between 3 to 12 hours depending on the specific product and environmental conditions. Allow full curing time before demoulding to prevent tearing. Check that the mould surface feels firm to the touch before removal. Gently flex and peel away the silicone from the master, taking care not to stretch or damage fine details. If the mould resists, double-check the curing time and try small movements to ease it off.

Step 5: Inspect and Use Your Silicone Mould

Carefully inspect your finished silicone mould for bubbles, tears or imperfections. Clean any residues and test the mould’s flexibility before using it for casting resin, wax, plaster or other materials. If the outcome reveals small flaws or you noticed air entrapment, adjust your mixing or pouring technique for future attempts.

Tips and Common Mistakes in Silicone Mould Making

Mixing technique and patience are essential for precise results. Mix slowly and thoroughly to prevent air bubbles. Be sure to avoid under-mixing, as streaks or unmixed portions can cause sticky spots. For intricate items, always use a suitable release agent to avoid damaging the original or the new mould. Overlooking the mixing ratio or de-moulding too soon are common pitfalls. If you encounter issues like incomplete curing or sticky surfaces, revisit your ratio and mixing habits for your next project.

Troubleshooting and Fine Details

Encountered air bubbles or curing problems? Slow mixing and the use of release agents and pressure pots help achieve flawless, detailed moulds. Always inspect finished moulds before use to avoid surprises.