* Low thermal conductivity: Tinplate is a relatively poor conductor of heat. This means it doesn't transfer heat very efficiently, so the heat from the soup dissipates quickly.
* Thin material: The thinness of tinplate means it has a small thermal mass. This means it doesn't hold much heat itself, so it can't effectively keep the soup warm for long.
* Lack of insulation: Tinplate cans don't usually have any insulation, which would help to slow down heat loss.
Here's a comparison:
* Metal like stainless steel or aluminum are better conductors of heat, which is why they're often used in thermal containers.
* Ceramic or glass are even better at retaining heat, especially with a vacuum between the inner and outer layers.
In summary, while tinplate is great for storing and preserving food, its properties don't make it a good choice for keeping soup warm for extended periods.