SXIII said:
It would still get quite hot inside an armour, especially during fights. Humans are after all a complex heat engine.
This is very true, it is THE reason we lost our body hair and grew bigger brains.
Not a lot of people realise that very very few animals actually sweat like we do (some give off pheromones, but its not sweat used to cool down like we have) Fur actually causes sweat to be less effective at cooling your body. A naked human will cool off faster from sweating than a clothed one.
Humans have the most advanced cooling system of any animal on this planet, and this extra cooling is what allows us to have larger brains. If any other animal tried to grow a brain as large as ours the brain would over-heat and die.
Its just like the computing industry atm, we need better cooling systems before we can get processors to run any faster! (safely, anyway)
Also, as a side note, the heat difference between white or black cloth is almost nothing, notice how many Arabian women wear all black? The material its made of has a much greater effect (namely, if the material allows your skin to 'breath'). Metal is very very ineffective, regardless of shininess or colour.
I suspect that armour was kept shiny because it was kept clean. I should think they were taught how to look after their armour. A full plate suite is very expensive, so knowing how to make it last as long as possible is invaluable. Keeping metal clean and polished helps protect it from rust and other forms of corrosion.
