Pores

I shaved today. When I shave, I usually just throw some hot water on my face a few times and pretend that that opened my pores and thus I will get a closer shave. But I think every time I do that I inevitably wonder if those few splashes of hot water actually did anything. I mean, I've never actually seen my pores open or close before, so how do I really know? How long does it take for a pore to open? Will ten seconds of hot water on my face open my pores? Do I have to close my pores back up with cold water when I am finished?