See our Mold Knife Demo
A mold knife is a specially modified utility knife with a curved blade. It is the second most critical part of your tool kit. This knife is the secret to making molds that produce seamless castings. When cutting through a block mold of silicone, the curved blade cuts a rounded key into the mold. The rounded key ensures perfect registration when the mold is banded back together.
When casting with molds, the seam line is the most obvious indication to a viewer that a mold was used. A noticeable seam line will count against you in competitions or important presentations. Cutting a mold open with a common razor knife is the quickest way to lower the value of your mold. A mold that has been cut open with a razor will not register well during casting and will create seam lines that take extra time to remove.