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When working with silicone rubber for mould making, Shore hardness is a key factor that influences the flexibility and durability of your finished mould. Many creators wonder if Shore hardness can be changed during the mixing process. Here, we clarify how this property is determined and what you can expect when selecting a silicone system.
How Shore Hardness Is Set in Silicone Rubber
The Shore hardness of silicone rubber is determined by its chemical formulation during manufacturing. This value, often selected when purchasing, defines how soft or firm the cured silicone will be. Once you receive your kit, the ratio of parts A and B—and the act of mixing—cannot alter the predetermined Shore hardness. The catalyst simply initiates the curing process and does not influence the final hardness. For example, “Liquid Mould” silicone allows buyers to choose a Shore hardness anywhere between 5 and 40 at the point of sale.
Selecting the Right Silicone for Your Project
If you need a specific Shore hardness, make your selection carefully before ordering. Products such as “Pure Mould” translucent silicone provide various hardness options, including 10, 13, 20, and 30 Shores. Harder grades suit detailed or larger moulds, while softer grades offer flexibility for capturing intricate features and undercuts. Read the product description and specifications to ensure the Shore hardness matches your intended use.
When Shore Hardness Selection Matters
Shore hardness greatly affects both demoulding and the mould’s lifespan. Jewellery makers and those producing fine details often opt for softer silicones (around 15-20 Shores), while moulds for repetitive casting may require something firmer. Always plan ahead, as post-purchase adjustment is not possible through the mixing process.
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Understanding how Shore hardness is set in silicone rubber will help you choose the right moulding material from the outset. If you’d like to explore hardness options in more detail, our main guide on Shore hardness of silicone rubber covers everything you need to know before your next project.