How do I mix non-toxic silicone rubber for moulds?

Understanding the Mixing Ratio

Most non-toxic silicone rubbers for moulds are two-component systems, typically labelled as parts A and B. They are usually mixed in a 1:1 ratio by either weight or volume. Always refer to the instructions for your chosen product to confirm the exact ratio, as some formulations might vary.

For example, “Pure Mould” liquid silicone rubber and “I–Gum” silicone putty both use a straightforward 1:1 ratio, making them especially user-friendly for hobbyists and professionals alike.

Step-by-Step Mixing Guide

• Accurately measure equal quantities of components A and B, using a digital scale for precision if possible.
• Pour both parts into a clean, dry container. Mix them thoroughly with a spatula or mixing stick, making sure to scrape the sides and bottom.
• Continue stirring until you achieve a uniform, streak-free mixture. This helps prevent under-cured or soft spots in your finished mould.
• Once mixed, use the silicone immediately as the curing process begins when both parts combine. For liquid types, pour gently to minimise bubbles; with putty, knead quickly and shape as needed.

Helpful Tips for Consistent Results

• Work in a dust-free, dry environment to avoid contamination.
• If you are new to silicone mixing, start with a small batch to practise the process.
• Check your specific product’s pot life and working time; for putty like “I–Gum”, expect about 20 minutes of flexibility, whereas liquids may cure faster.