Here's why:

* Composition: Ink is primarily a mixture of pigments, solvents, and resins. These components are generally poor conductors of heat.

* Liquid State: While liquid, ink is not a good conductor of heat compared to metals. Liquids, in general, are less efficient heat conductors than solids.

* Insulating Properties: The pigments and resins in ink can actually act as insulators, hindering the flow of heat.

Therefore, ink is more accurately described as a thermal insulator.