CLAY:

Claying Mixture For Forges.

The materials should be thoroughly mixed dry and then wet down to the consistency of common mortar, constantly stirring the mass as the wetting proceeds. A rough mold shaped to fit the tuyère opening, a trowel, and a few minutes’ time are all that are needed to complete the successful claying of the forge. This mixture dries hard and when glazed by the fire will last.

Plastic Modeling Clay.