Most VFI molding rubbers must sit for a minimum of 16 hours at room temperature (77°F) before they can be demolded. After demolding, they must sit for another 3 days outside of the mold to develop the necessary green strength for molding purposes. Even though the mold can be used after 3 days, keep in mind that the material requires 7 days to develop full physical properties. Note: during the 3 days, fully support your mold to prevent it from forming into an unwanted shape.