Here's why:

* Composition: Plasticine is primarily made of a mixture of oil, wax, and a clay-like substance. These materials are generally poor conductors of heat.

* Structure: The structure of plasticine is relatively dense and solid, but it lacks the free electrons that metals have, which are essential for efficient heat conduction.

* Thermal Conductivity: Plasticine has a low thermal conductivity, meaning it resists the flow of heat.

In summary: While plasticine can still transfer some heat, it does so very slowly compared to materials like metals.