A molten material apparatus can include a container including a wall at least partially defining a containment area and an opening extending through the wall. The molten material apparatus can include a protective sleeve mounted at least partially within the opening of the wall of the container. A thermocouple can be positioned within an internal bore of the protective sleeve. A method of processing molten material can include inserting a thermocouple into a protective sleeve fabricated from a refractory ceramic material, and measuring a temperature of material within a containment area of a container with the thermocouple.